The Garden Shed

A Community Newsletter published by the Piedmont Master Gardeners

February 2024-Vol.10,No.2

 

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  Are Mother Trees Real?

Characteristics of Drought-Tolerant Perennials

The Edible Garden in February

Starting Seeds Indoors

The Ornamental Garden in February

Praying Mantids

For comments, questions or suggested topics for future Garden Shed articles contact us at: garden-shed@piedmontmastergardeners.org.

If you have specific gardening questions or need help to solve a gardening problem, our Horticultural Help Desk is a free community resource and can be contacted at 434-872-4583 or by email: albemarlevcehelpdesk@gmail.com.

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Who We Are

We are members of the Piedmont Master Gardeners, which simply means we have all been trained to share the scientific expertise of Virginia Tech and the Virginia Cooperative Extension Service. More important, we are your friends and neighbors with a passion for gardening – and learning more about it. MORE

Table of Contents

In the Ornamental Garden

Characteristics of Drought-Tolerant Perennials

By Pat Chadwick

How can I tell if a perennial is drought-tolerant?

Tasks and Tips

The Edible Garden in February

By Ralph Morini

February is the time to start planning this year's edible garden, acquiring and planting seeds for indoor germination, and pruning fruit trees and shrubs. Let's get started.

Feature

Are Mother Trees Real?

By Ralph Morini

Recent research appears to demonstrate that rather than a purely survival of the fittest arrangement, trees communicate and share resources with each other through fungal (mycorrhizal) networks.

In the Edible Garden

Starting Seeds Indoors

By Cleve Campbell

We've reprinted Cleve Campbell's classic article on starting seeds indoors, with a few updates for 2024.

Tasks and Tips

The Ornamental Garden in February

By Pat Chadwick

Time to gear up for spring

Upcoming Events

Upcoming Events

By Cathy Caldwell

Mark your calendar!

General Gardening

Praying Mantids

By Fern Campbell

Friend or foe in the garden?

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Are Mother Trees Real?

• February 5, 2024
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The term “Mother Tree” was coined by Canadian Professor of Forest Ecology at the University of British Columbia, Suzanne Simard. Her research, from the 1990s through today, indicates that trees in a forest, rather than simply competing with each other for survival, form communities that include trees and fungi that share their nutrients to strengthen overall community survival. Further, her research suggests that the largest trees share their photosynthesized carbon-based sugars with other tree species in their community. Dr Simard called them Mother Trees because they appear to favor the needs of their offspring compared to unrelated trees. She maintains that mycorrhizal networks link trees of multiple species, sharing sugars from trees that produce more than they need with those who don’t have enough, and the fungi who are not able to photosynthesize. In return, the fungi absorb water and nutrients from the soil and pass it on to trees in need in the community.

Trees have a symbiotic relationship with microorganisms in the soil, like fungi. Fungi form white thread like colonies on tree roots as seen in the panel on the right. Trees give carbon to the fungi in the form of sugar and in return fungi give the trees essential minerals such as nitrogen and phosphorus. From SITN Boston, “Exploring the Underground Network of Trees” by Valentina Lagomarsino, figure by Hannah Zucker, Harvard University, CC BY-NC-SA 4.0

This idea of cooperative forest communities runs counter to the historical belief that nature is simply a survival of the fittest competition between plants and animals and conflicts with the conventional lumber-industry-based forest management practices of clear-cutting forest sections and replanting monocultures. In Simard’s view, this disregards the evidence and ignores the potential benefits of diverse and cooperative community relationships. From a commercial standpoint, her data appears to show that the clear-cutting/monocultural replacement practice reduces forest health and ultimately lumber production.

Simard’s History in the Forest

Suzanne Simard is the daughter and granddaughter of traditional foresters who cut trees selectively and used horses to transport them. Growing up in the forest, she came to love the apparent relationships she observed between the forest dwellers. Her love of nature, and forests in particular, led her to summer forestry jobs during graduate school and full-time work as a Research Scientist for the BC Ministry of Forests. During her early work she saw that forests that were clear cut for lumber were slower to regrow when row-planted with a single tree species, than trees of multiple species ranging from young to mature, naturally spaced and selectively harvested.

Mycorrhizal fungi expand the root zone of plants. Photo: NCSU.EDU

Trying to understand why this was true led her and her team to perform decades of research. Early evaluations demonstrated that the healthy trees in the natural forests had root systems that were tied extensively to networks of the mycelia of mycorrhizal fungi. With further testing, she found that the trees were sending a portion of the photosynthetic sugars they generated to the fungi, in exchange for nutrients that they needed. This was demonstrated by inserting radioactive carbon isotopes into multiple trees and measuring whether and what nutrients were transmitted between the trees through the fungal mycelia. The measurements showed that in fact, sugars were transmitted both for fungal use and for passing on to multiple tree species in the community. At the same time, soil-based nutrients were transmitted from fungi to trees that were part of the same mycorrhizal network. Later study showed that the fungi passed some of the sugars on to trees of both the same and different species, running counter to the historical beliefs of pure competition between plants and apparently indicating that the mature trees influence which trees-in-need receive the nutrients. While more research is needed to establish how much nutrient is transferred, one study found that an average of 6% of required sugars were received through the network by the receivers from the senders.

Network model showing the linkages between Douglas-fir trees through the mycorrhizal network. The arrow points to the most highly connected tree. Diagram from Beiler et al. 2010. From MotherTreeProject.org

Further work demonstrated that the oldest, largest trees in the forest area, those with the broadest crowns, were the largest donators of the sugars, and that the largest donations went to their direct offspring. Simard began calling these large older trees “Mother Trees” to emphasize the observation of parental support for offsprings and to present the findings in terms that would be understandable by the public. Other researchers, who support her work but object to using human terms to characterize the plant/fungal relationships, prefer the term “Hub Tree”.

To Simard, these findings were exciting, if not unexpected, given her childhood preconceptions. But when she attempted to promote the concepts and benefits of building forest communities, she confronted resistance from the historical establishment in the forestry industry whose belief was that clear cutting and regrowth of row planted monocultures produced the most lumber at the lowest cost. The idea of leaving the oldest, largest trees in the forest while selectively removing younger, smaller trees held little appeal.

Her original experiments and reports took place during the 1990s. She has spent the decades since then expanding the scope of her research while building understanding and acceptance of her findings in the forestry industry and beyond.

What the Skeptics Say

While there is growing acceptance of Simard’s claims, many researchers and forestry management professionals only partially accept and in some cases reject her findings.

Forestry organizations remain largely wedded to clear cutting and replacing the cut trees with seedlings of a single species, widely-spaced and fungus-free. Leaving the largest trees in place, taking up space in the forest, in their minds reducing lumber production and increasing the cost of harvesting, is hard for the industry to accept. They are more inclined to find fault with Simard’s research techniques.

While many forest scientists support Simard’s conclusions, others feel that her assertions are overstated. The objectors agree that fungal networks exist in the forest, but they believe that plants are working more in their self-interest than as a cooperative community. For example, the mycorrhizae can penetrate tree roots to both deliver and extract nutrients from their hosts. Many doubters believe that the fungi trade materials with trees because it serves their own needs, not necessarily to also support the needs of others.

Simard’s research has measured cooperation mainly between Douglas Firs and Paper Birch trees. Other research done in forests and labs around the world, monitoring different species, appears to show inconsistent evidence of her claimed cooperation and nutrient trading between trees through fungal networks. Similarly, indications of favoring offspring over other trees of the same and related species are not conclusive.

Acceptance of fungal networks and transfer of sugars and soil nutrients within the network communities, is generally widespread. However, researchers point out that Simard’s work has been done in the forests of Western Canada, on a small variety of tree species, affected by the region’s specific local environmental and soil conditions. Research from other geographic areas shows less consistent and at times conflicting results.

Questioners also point out the existence of parasitic relationships between trees and fungi, and that the allelopathic emissions by some trees (black walnut for example) demonstrate the competitive aspects of forest relationships.

So, the argument is generally not so much about whether networks exist or that trading of nutrients between trees and fungi occurs. Rather it challenges the concept of systematic sharing of nutrients between different species and prioritization of supporting offspring ahead of non-related trees. The conflicting data indicates that additional research is needed to determine the validity and breadth of Simard’s conclusions.

Future Direction

Simard has been working in the field for over 30 years and her team’s experiments have been detailed and thorough. Research by others around the world, while not always reaching the same conclusions, has been building agreement with many of her basic premises. Continuing research, including more species, different environments, and varying soil conditions, is needed to fully test her basic claims and add credibility and clarity to her conclusions. A growing base of such research is testing her hypotheses.

Climate change is adding significance to the investigations. The importance of pulling carbon from the atmosphere and utilizing live trees and soil to store it sustainably, has never been more important. The Mother Tree concept of photosynthesizing carbon from the atmosphere and using it to grow more trees faster via mycorrhizal networks has strong appeal. But continuing research covering a range of species and environments is clearly justified.

In a broader sense, climate change has also illustrated the importance of biodiversity and in building healthy communities that include plant, animal (including humans), and microbial life. While the Mother Tree concept, and more broadly, the idea that communities are formed by trees and fungi, are a relatively narrow portion of the larger diversity picture, their relationships are certainly a part of it. There is little doubt that the study of these relationships is important and deserves continuing research as the criticality of the planet’s declining tree population in the face of climate change, a growing human population and a reduction of species around the world, becomes more obvious. Stay tuned…

Featured Photo:  Ralph Morini

SOURCES:

Finding the Mother Tree, Suzanne Simard, Alfred A. Knopf, 2021, 348 pages.

The Hidden Life of Trees, Peter Wohlleben, Greystone Books Ltd., 2016, 272 pages.

Entangled Life, Merlin Sheldrake, Random House Books, 2020, 352 pages. (Note Chapter 6 titled: Wood Wide Webs).

“About Mother Trees in the Forest,”  The Mother Tree Project,  https://mothertreeproject.org/about-mother-trees-in-the-forest/

“Mother Trees are Intelligent: They Learn and Remember,”  Scientific American, May 4, 2021, https://www.scientificamerican.com/article/mother-trees-are-intelligent-they-learn-and-remember/

“Exploring The Underground Network of Trees – The Nervous System of the Forest,” Valentina Lagomarsino, with figures by Hannah Zucker, Science in the News, Harvard University (2019)

“Are Trees Talking Underground? For Scientists it is in Dispute,” NY Times, June 20, 2023, https://www.nytimes.com/2022/11/07/science/trees-fungi-talking.html

“Can Plants Talk to Each Other,” Katie Sylvester, Biomechanics in the Wild, Katie Sylvester, 2019: https://sites.nd.edu/biomechanics-in-the-wild/2019/03/06/can-plants-talk-to-each-other/

Net transfer of carbon between ectomycorrhizal tree species in the field, Simard et al, Nature, August 7, 1997: https://www.nature.com/articles/41557

“How do Trees Collaborate,” NPR/Ted Radio Hour, January 13, 2017: https://www.npr.org/transcripts/509350471

The Ornamental Garden in February

• February 1, 2024
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Although the weather is wintry outside, the days are getting noticeably longer, signaling the time to start gearing up in earnest for the spring gardening season.  In the meantime, lots of actions can be taken now to prepare for spring planting.   

Complete orders for new seed from catalogs and on-line resources.  Order early to improve the chances of getting the seeds you want. Once the seeds arrive, label the front side of each packet with the year so that, in the future, you can see at a quick glance how old any unused seeds are.

Inventory your seed-starting supplies to make sure you have ample quantities of cell packs, transplant pots, potting mix, trays, plant tags, fertilizer, etc.  Don’t forget to check the light bulbs in grow lights to make sure they are in good operating order.

To get a head start on this season’s garden, think about starting seeds indoors and plan accordingly.  Follow the recommendations printed on seed packages for how far in advance of the last frost date (which falls between April 15 – 25 on average) to start seeds indoors.  It’s important not to start them too soon.  Otherwise, the seedlings may be spindly and weak and will not transplant well.  Also, some seedlings that are started too early could grow too large for their containers and require re-potting before it is safe to plant them outside.  For more information on seed starting, check out this Garden Shed article on How to Start Your Garden Seeds.

If you have seeds left over from previous years, do a germination test to make sure they are still viable.  Viability often depends on the plant species, the quality of the seed, and the conditions under which the seeds have been stored. According to Johnny’s Selected Seeds Seed Storage Guide, zinnia seeds are viable for about 5 to 6 years, whereas phlox seeds are only viable for about 2 years. To test seeds for viability, moisten a paper towel and place about 10 seeds of the same variety on it.  Roll up the paper towel and put it in a plastic bag but don’t seal the bag.  Place the bag in a warm area.  Check the seeds daily and keep the paper towel damp but not soggy.  After several days or so, see how many seeds have sprouted.  If at least half of them did, then the rest may sprout as well.  If not, then it may be best to buy new seed.

This is the ideal time of year to prune most deciduous trees while they are dormant. Prune to remove dead, weak, diseased, or crossing branches. If you are a novice at pruning, see Virginia Cooperative Extension (VCE) Publication 430-456, A Guide to Successful Pruning: Pruning Deciduous Trees/VCE  and VCE Publication 430-457, Pruning Evergreen Trees.

This is also the ideal time to prune summer-flowering shrubs such as Abelia, beautyberry, or Caryopteris.  Spring-blooming shrubs such as forsythia and flowering quince should not be pruned until after they finish flowering later in the spring.  For flowering shrubs, timing of pruning is critical. Spring-flowering shrubs flower on “old wood” — the flower buds were produced  in the year prior to blooming; Summer-flowering shrubs flower on “new wood,” — the buds are produced during the spring/summer in the same year that the blooms appear.  Before making that first cut, see Selecting Plants for Virginia Landscapes: Showy Flowering Shrubs, which discusses a large number of flowering shrubs, and for each one, helpfully indicates whether it produces flower buds a new wood or old wood.  See also VCE Publication 426-701, Shrubs: Functions, Planting, and Maintenance .

Inspect stored tender bulbs, tubers, or corms periodically and lightly moisten them if they are shriveled. If any appear soft or diseased, discard them now.  Otherwise, keep checking them periodically until time to plant them in spring.

Check evergreen trees for drought stress caused by either frozen soil, which prevents the plant from taking up water, or from lack of rain or snow over the winter.  If water is needed (check the soil around the tree for dryness), wait until the outside temperature rises above 40°F and use a soaker hose to water the root zone.   If possible, do this early enough in the day to allow the water to soak in before the soil re-freezes.

Monitor trees and shrubs for deer, rabbit, or vole damage.  Look for scraped or gnawed bark.  Pull back mulch a couple of inches away from the trunk to discourage vole damage.

Cut back ornamental grasses before spring growth occurs.  If you wait until spring, you may damage the newly emerging grass blades.  An easy way to cut back large clumps of dormant grasses is to tie a bungee cord around the clump and use pruning shears or an electric hedge trimmer to cut back the foliage to a few inches above ground.  Try not to cut too close to the crown.  Otherwise, moisture may settle in the crown causing it to rot.

Look for emerging foliage of early blooming daffodils, snowdrops, hyacinths, and other spring bulbs. If daytime temperatures are above freezing, the foliage can tolerate short periods of frosty temperatures without harm.  If prolonged freezing weather is predicted, protect the foliage with frost covers, a layer of newspaper, light mulch or chopped leaves.

Carefully trim away old foliage from hellebores so that you don’t damage new emerging foliage and flower buds.

Arrange to have your lawnmower serviced now if you didn’t get around to it at the end of the last growing season. By taking care of this task during the dormant season, you can beat the crowds at the repair shop before warm weather arrives.

Avoid walking on ice or frost-covered lawns.  Foot traffic on frozen grass can damage the grass blades and compact the soil.

Keep tabs on the health and well-being of your houseplants. Inspect them for pests every time you water them.  Common pests include white flies, scale, fungus gnats, spider mites, and mealy bugs.   Treat as needed at the first sign of a problem.  The University of Minnesota extension publication on Managing insects on indoor plants/UMN offers sound advice on houseplant pests and includes photos of the most common ones.   Clemson Cooperative Extension publication HGIC 2252 Common Houseplant Insects is another useful source for advice.

This is a good time to start new houseplants from cuttings. Use a sharp knife to sever a 2” to 6” long cutting just below a node on a stem.  Remove all but the top 2 or 3 sets of leaves. Many cuttings may be rooted in water, but for more advice on this and other plant propagation methods, see VCE Publication No. 426-002, Propagation by Cuttings, Layering and Division.

As berries, seeds, and other natural food sources become scarcer in the landscape, continue providing supplemental food and fresh water for the birds and don’t forget to keep the feeders clean.  See these tips from the Audubon Society Three Easy But Important Ways to Keep Your Bird Feeder Disease-Free.  Also, join the annual Great Backyard Bird Count, which is a free, fun, and easy event that engages bird watchers of all ages in counting birds over a four-day period later this month and reporting their sightings online.  For further information and to register for this event, see birdcount.org.

Invasive Watch:  Paradise Tree or Tree of Heaven (Ailanthus altissima) is a dreaded nonnative invasive that threatens natural areas, agricultural fields, disturbed areas, and homeowner properties. For trees with trunks 4 to 6 inches in diameter, a basal bark treatment with an herbicide is effective from February 15 to April 15. See the Blue Ridge PRISM (Partnership for Regional Invasive Species Management) Factsheet for information on how to identify and eradicate this invasive. The nonnative insect pest, Spotted Lanternfly, prefers, and may even require, Ailanthus altissima trees to complete its lifecycle.

February is a cold and wintry month, but Valentine’s Day, which traditionally occurs mid-month, provides welcome respite from the weather with its promises of candlelight, hearts, and flowers.  To keep those Valentine’s Day flowers – or any floral display – going strong, see this Garden Shed article on How to Keep Cut Flowers Fresh.

 

Featured Photo: Snowdrops (Galanthus nivalis), Courtesy of Missouri Botanical Garden PlantFinder

PMG Gardening Resources/Monthly Gardening Tips/February

The Edible Garden in February

• February 1, 2024
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• 2 Comments

For edible gardeners who grow spring vegetables and fruit growers who need to prune before new growth starts, February is the month to kick off the season. The lengthening days and typically warming temperatures urge us to get things moving. Here is a suggested to-do list.

 Planning

It makes sense to start with a plan:

• Decide what you want to grow, review best times to grow it, and where you want to place it in the garden. Crop rotation on a 3-year cycle is best for soil and helps minimize soil pest and disease issues.
• The USDA has recently reviewed the impact of climate change and modified its Plant Hardiness Zones. This has changed the ratings of many areas, including Albemarle County, VA, changing our local published Hardiness Zone from 7a to 7b. The result is a 10 to 20 day increase to the growing season for many crops. This change hasn’t impacted the VCE publication Virginia’s Home Garden Vegetable Planting Guide map yet, but interested local gardeners who follow temperature forecasts can begin to reference the zone 7b planting/harvesting schedules to modify planting dates and maybe try some new crops.
• Start a journal that records what you grow, where you grow it, when you plant and harvest it. Also track any insect or disease issues that arise to guide decisions next year.

Growing from Seed

Starting plants from seed is less expensive, offers more choices and gives gardeners the ability to control conditions and timing of transplanting. It also gets our hands in the soil earlier than outdoor planting or purchasing transplants from garden centers.

• If you plan to start plants from seed, it’s time to acquire seed for spring crops. There are plenty of on-line catalogs and local garden retailers to choose from. Put some thought into varieties to grow, working to balance the appeal of heirlooms with the disease and pest resistance benefits of new hybrids.
• If you plan to use seeds from last year, check their viability, as recommended in the Garden Shed article Good Seeds, Bad Seeds.
• Folks who are new to indoor seed starting can find good advice on everything from equipment to soil to timing from the Garden Shed article Starting Seeds and be sure to read Starting Seeds Indoors in this month’s Garden Shed.

Crops grown from seed that can be started in mid to late-February for transplanting in mid to late-March include broccoli, cabbage, cauliflower, kale/collards and head lettuce. When these are moved outside, they can be replaced indoors with warm weather vegetables like tomatoes and peppers for transplanting in late-April/mid-May.

Optimum time from germination to transplanting varies somewhat by crop, with 6 weeks being a general guide. Waiting too long leads to leggy plants that may not be as hardy when moved outside.

Light is important. Natural light requires a south facing window or solarium. Artificial light can work with either a grow light or a two-bulb fluorescent fixture that has one cool and one warm bulb.  The internet is loaded with options for non-DIYers.

Most plants prefer a temperature of 65-75°F. If the growing area is cooler than this, a heating mat is a good idea for both germination and seedling growth.

Containers can be anything from purchased or homemade flats to vegetable cans to yogurt containers. Be sure that they have drainage holes. Space seeds in flats according to the package directions, and thin overly dense seedlings soon after germination.

Be sure to use a fresh potting mix.  We recommend using non-peat based potting soils to reduce negative environmental impacts. There are numerous non-peat potting mixes available and they can be strengthened by adding compost.

If you reuse pots or trays from last year, minimize disease risks by cleaning and disinfecting them with a 10% bleach solution.

Plant seeds at a depth of 2-3 times their diameter (not length). Moisten thoroughly after planting. Keep moist, not soaked. If the seed dries out, it won’t germinate.  Too wet invites fungus and damping off.

To help maintain soil moisture while waiting for germination, cover pots or flats with clear plastic wrap or other clear cover. Keep soil below the top of the flat or container so that any cover is an inch above the soil. Remove cover immediately after germination.

Getting a Jump on Weed Control

If you are starting a new outdoor bed or want to minimize weed issues early in the growing season, consider solarization or occultation. These methods involve using clear or black tarps respectively to smother weeds prior to planting, as a replacement for tilling, manual removal or herbicide use.

The ideal first step is to cut all growing vegetation in the garden bed as close to the ground as possible. Moisten the ground well. Then cover beds with plastic sheeting or tarps, well secured around the edges with bricks, stones, boards or soil. Clear tarps heat the soil a bit more while black tarps keep light out. Heat and moisture will cause weed seeds to germinate. The continuing heat then kills the vegetation. Leave the tarps in place for 4-6weeks, then remove them. Leave the dead vegetation as mulch or remove it and smooth the surface to be ready to plant.

A thorough description of these processes is offered in the article Using the Sun to Kill Weeds and Prepare Garden Plots from the University of Minnesota Extension.

Fruit Grower Tasks 

 Small fruit growers should generally prune canes, bushes, or vines late in the winter, just before new growth starts. Pruning can be done to remove dead, weak, diseased, and damaged plant parts, thin centers for light penetration and air circulation, and to train grape vines and cane hedges. Detailed guidance on pruning, selection and care of blackberries, raspberries, strawberries, blueberries, and grapes is available in the VCE publication Small Fruit in the Home Garden.

Fruit trees are also best pruned just prior to starting spring growth; pruning helps to build a strong frame while encouraging light penetration and air movement. Specific help with selection, and care, including pruning, of various fruit trees is given in the VCE publication Tree Fruit in the Home Garden.

A broader-based article on good pruning practice is available in the Garden Shed article A Pruning Primer: Tools, Techniques and Timing.

Soil Testing

If the garden is due for a soil test (we recommend about every three years), now is a good time to do it. Healthy soils that provide the right amount of macro and micronutrients yield larger harvests from healthier plants with less effort from the gardener. The process is summarized in the VCE publication Soil Sampling for the Home Gardener. Sampling kits are available at the local extension office. In Charlottesville/Albemarle the office is located at 460 Stagecoach Rd, Charlottesville. Phone is 434-872-4580. Test kits are usually available in bins located outside the building entrance off Stagecoach Rd.

Finally, don’t neglect your gardening tools and equipment. Now is the time to clean, disinfect, sharpen etc, based on the item, to be sure you are ready to get the garden going in the spring.

Spring is Coming

It is time to launch the 2023 gardening year. The garden can be a place to escape the noise of the world while reconnecting with nature. It is that way for me, and I hope it is a place of enjoyment and learning for you, too. See you next month at The Garden Shed.

Upcoming Events

• February 1, 2024
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February Tree Basics Class: Winter Tree ID: Buds ‘n Bark

Tuesday, February 6 @ 7:00 p.m. — 8:30 p.m. on Zoom
FREE ⇒Please register here

Without leaves, trees are often overlooked in winter because various shades of gray cover the landscape. This class will find color in buds and even twigs, and take a closer look for the patterns that separate individual species. Join Charlottesville Area Tree Steward Emily Ferguson for this entertaining and informative talk about how to ID trees from their buds, bark, and branching patterns.

 

The 39th Annual PLA Seminar

Wednesday, February 21, 2024
​The Paramount Theater, Charlottesville, VA

Topics:

–What is a Forest Garden and How Can You Create One?

–A Bountiful Year: Six Seasons of Beauty from Brandywine Cottage

–An Evolution of Purpose: Japanese Gardens as Healing Spaces

–Managing Native Landscapes: Planted and Naturally Occurring
​

For more information and to purchase tickets ⇒ Here

 

Coming up in March . . .

Garden Basics: A Year in the Life of a Vegetable Garden–A Gardener’s Path

March 16 @ 2:00 pm – 4:00 pm,  Trinity Episcopal Church 1118 Preston Avenue, Charlottesville

Characteristics of Drought-Tolerant Perennials

• February 1, 2024
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• 1 Comment

Why do some perennials sail through prolonged hot, dry weather unscathed while others wilt, turn brown, and bloom poorly if at all?  To answer the question, let’s take a look at the characteristics of drought-resistant plants as well as strategies for dealing with drought conditions. But first, what do we mean by drought?

DROUGHT CONDITIONS DEFINED

Simply defined, a drought is a period of prolonged dry weather when the soil is depleted of moisture due to a lack of precipitation or irrigation.  Here, in central Virginia, a typical drought can last from several weeks to several months.  On the western half of the country, droughts can last for years.

In addition to prolonged dry weather, drought stress on plants may be exacerbated by high light intensity, drying winds, and prolonged high temperatures.  According to Lee Reich’s book entitled The Ever Curious Gardener, “High temperatures cause plants to desiccate and consume stored energy faster than it can be replenished.  Stress begins at about 86 degrees Fahrenheit, with leaves beginning to cook at about 20 degrees above that.”

IDENTIFYING DROUGHT-TOLERANT PERENNIALS

At the end of the 2023 growing season, members of the Piedmont Master Gardeners Association in the Charlottesville/Albemarle County area participated in an informal survey on drought-tolerant perennials. The goal was to share information on species that performed well over the summer and fall despite the prolonged drought conditions. The observations gleaned from the survey resulted in a list of approximately 50 drought-resistant perennials that met or exceeded expectations. The interesting thing about these plants is that they exhibited many distinguishing characteristics that make them suitable for hot, dry conditions.  Most of the species listed are native, but some non-natives are also included.  Space doesn’t allow listing all 50 plants here, but a few representative species include:

• Asclepias (milkweed)
• Coreopsis (tickseed)
• Dendranthema (hardy chrysanthemum)
• Eryngium (rattlesnake master)
• Gaillardia (blanket flower)
• Panicum virgatum (switchgrass)
• Salvia (sage)
• Sedum
• Solidago (goldenrod)
• Symphyotrichum (aster species)

This was a very informal survey with mostly predictable results.  However, there were a few surprises:

• Some sun-loving species benefitted from shade. For example: In one garden, Solidago ‘Fireworks’, a popular clump-forming goldenrod, flowered normally in full sun.  However, the bloom time seemed shorter than normal.  Meanwhile, the bloom time on a nearby ‘Fireworks’ clump that received some afternoon shade lasted several days longer.
• Some moisture-loving plants performed better than expected. In another garden, Lobelia siphilitica, a moisture-loving plant, bloomed well in a rain garden setting despite the lack of moisture.  That it performed as well as it did was surprising. More surprising, “volunteer” Lobelias that had sprouted nearby in a drier spot also performed well. As luck would have it, they sprouted near a house foundation wall, which apparently held some moisture in the soil.
• Drought tolerance varied within species. In general, asters are drought tolerant, but some varieties performed better than others.  Aromatic asters (Symphyotrichum oblongifolium), which bloom in late fall, showed no signs of drought stress.  But New York asters ( novi-belgii), which typically bloom earlier in the fall, were clearly stressed with brown leaves toward the bottom of stems, discolored leaves on upper stems, slightly smaller blossoms, and fewer blossoms.
• Performance varied from site to site. Pink muhly grass (Muhlenbergia capillaris) performed well for one master gardener in their amended red clay soil.  However, two other master gardeners reported that theirs performed poorly. One of the gardeners mused that wet conditions over the previous winter might have damaged the root system.

While more study would be useful, the following preliminary conclusions can be drawn from this informal survey:

• As growing seasons become warmer, some perennials normally grown in full sun may benefit from shade, particularly during the hottest part of the day.
• Some moisture-loving perennials may thrive in drier soil if grown near a rock wall, building foundation, or other structure capable of holding moisture in the soil.
• Drought tolerance may vary among members of a given species with some varieties showing greater drought resistance than others.
• The degree of drought tolerance may be site specific with regard to soil composition, drainage, amount of sunlight, and other variables that occur from garden to garden.

CHARACTERISTICS OF DROUGHT-TOLERANT PERENNIALS

As mentioned earlier, in exploring what makes a perennial drought tolerant, a number of specialized evolutionary adaptations or characteristics were noted. For example:

Small or narrow leaves:  The smaller the leaf, the better it can reduce foliar evaporation and shed heat.  Examples: Threadleaf Coreopsis (tickseed), Perovskia atriplicifolia (Russian sage), Achillea millefolium (common yarrow), and grasses with narrow blades.

Thick waxy cuticles:  All plant leaves have a cuticle, which is a waxy coating that protects the leaf’s cellular tissue and reduces moisture loss.  Some plant species have exceptionally thick cuticles that reduce evaporation.  This characteristic is particularly beneficial in windy sites.  Examples:  Sedum species, hellebores, and some ferns such as Christmas and holly ferns.

Deep root systems:  Long tap roots reach deep into the soil in search of moisture.  This characteristic allows plants to survive periods of surface-level drought. Examples:  Asclepias (milkweed), Baptisia australis (blue false indigo), and some native grasses such as Panicum virgatum (switchgrass).

Hairy or fuzzy-textured leaves:  Fine “hairs” or fuzz provide a little shade.  They also slow the movement of air over the leaf’s surface, trap humidity, and slow evaporation of water from the leaf. Examples: Salvia argentea (silver sage), Stachys byzantina (lamb’s ear), and Verbascum (mullein).

Reflective foliage color:  Gray-green or silver leaves reflect light and heat from the sun, which reduces evaporation and keeps the plants cooler. Examples:  Artemisia (wormwood), Santolina (lavender cotton), and Cerastium tomentosum (snow-in-summer).

Fleshy stems:  Thick, often gel-filled stems can store moisture for long periods of time.  Examples: Opuntia (prickly pear cactus), Yucca, Agave, and Echeveria species.

Slow growth rate:   Slow growing plants such as cacti and succulents have fewer leaves and stems to support during dry periods.

Age of the plant:   Root systems on newly planted perennials are generally small and inadequate for handling drought conditions.  After a year or two in the ground, the roots should be more extensive and better adapted for drought tolerance.

SIGNS OF DROUGHT AND HEAT STRESS IN PERENNIALS

Some signs of drought and heat stress to look for in perennials include the following:

• Leaves may take on a dull look initially. As stress from lack of water deepens, the leaves may curl or wilt.  These signs indicate that the roots are not taking up sufficient water.
• The plant may droop or splay open in the middle. If the problem is not detected in time, the plant may not rebound even after receiving supplemental water or rain.
• Plant growth slows and may stop altogether resulting in stunted plants.
• Flower buds may not develop resulting in fewer blossoms. If they do develop, the flower size may be smaller than normal.

STRATEGIES FOR DEALING WITH DROUGHT

Choosing suitable water-wise perennial species is just the first step in creating a drought-tolerant garden.  The following are some strategies for establishing them and keeping them as healthy and vigorous as possible so that they are better equipped to thrive in hot, dry weather:

• Know your planting site conditions. Choose perennials that are suitable for your specific growing conditions.  Among other things, this means knowing: the soil type (sand, clay, humus, or some combination), how well it retains moisture, how well it drains, the amount of sunlight it receives, and the pH.
• Avoid planting in windy sites, which tend to dry out fast. If this is not possible, then try blocking the wind with strategically placed vines, shrubs, trees, or trellises.
• Plant small specimens that will adapt to the soil conditions faster than larger specimens and ultimately require less water.
• Group plants together with similar needs for sunlight, nutrients, and moisture. Either avoid plants that require a lot of water or group them near a water source.
• Space out new plantings so that they are not crowded and amend planting holes with compost or cow manure to help hold in moisture.
• Keep new plantings watered for their first season or two to allow them to develop an extensive root system.
• Apply a layer of mulch or compost around new plantings to cool the root zone and help retain moisture. If you’re trying to avoid using a lot of mulch, plant ground covers that will fill in the spaces around new plantings and shade their roots.
• Water established plantings deeply and infrequently, preferably using drip irrigation, to encourage roots to expand deeper into the soil. Water in early morning or in the evening to curtail loss of water through evaporation.
• Keep planting sites weed free to prevent competition with perennials for the same moisture, sunlight, and nutrient resources.
• Divide plants often to stimulate new root growth and improve plant vigor. In general, most perennials benefit from being divided about every 3 to 5 years.
• Provide shade.  The combination of too much direct sun and extreme heat will stress all but the toughest, most drought-tolerant plants.  For perennials that suffer from heat and drought stress, site them near shrubs, trees, or physical structures that will provide some shade during the hottest part of the day.

THE TAKEAWAY

The updated 2023 United States Department of Agriculture’s Plant Hardiness Zone Map drives home the fact that our climate is becoming warmer. Extreme weather events such as lack of precipitation and prolonged high temperatures are making gardening more challenging than ever. To compensate, we need to be more selective in the species we grow. Our choices are made easier if we are cognizant of the characteristics that make a plant drought tolerant and if we apply a few simple gardening strategies to keep the plants healthy and well maintained.

Feature Photo of drought-tolerant Agastache ‘Black Adder’ and Heliopsis ‘Summer Sun’ by Pat Chadwick

SOURCES

A Gardener’s Guide to Botany (Zona, Scott, PhD, 2023)

How Plants Work, The Science Behind the Amazing Things Plants Do (Chalker-Scott, Linda, PhD, 2015)

The Ever Curious Gardener: Using a Little Natural Science for a Much Better Garden (Reich, Lee, 2018)

Charlottesville Weather in 2023, Extreme Weather Watch

Native Plants and Cultivars for the Northern Piedmont, Piedmont Master Gardeners Website

Perennials:  Culture, Maintenance, and Propagation, Virginia Cooperative Extension Publication 426-203

Drought Stress Impacts on Plants and Different Approaches to Alleviate Its Adverse Effects, National Institutes of Health, National Library of Medicine, National Center for Biotechnology Information Published online 2021

How to Recognize Plant Heat Stress, Utah State University Extension

Plant Hardiness Zone Map, 2023 United States Department of Agriculture

Soil Management in Home Gardens and Landscapes, Penn State Extension article

 

 

Starting Seeds Indoors

• February 1, 2024
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• 0 Comments

Starting seeds indoors is the perfect “fix” for the gardener with cabin fever and a need to get their hands in the soil or simply a desire to get a head start on spring. Despite the frigid temperatures, February is the time to make a seed-planting schedule, to make those final seed purchases, to collect transplant containers and to start seeds indoors for the upcoming gardening season. With a small investment, and a bit of space and care, you can grow healthy transplants that are already to go into the ground outdoors when the proper time arrives.

Why start seeds indoors?

• Growing transplants from seed gives the gardener more choices than are normally available in gardening centers or other retail outlets.
• By growing your own transplants, you can control when you plant them outside. There’s no need to wait until they are available in a retail outlet or to wait for a mail order supplier to ship on a predetermined date.
• Indoor seed starting definitely saves you money. You might not reap these savings at first  — if you have some first-year-set up costs.
• Growing your own transplants increases your garden’s output.  How?  Well, you get a 2- to 8-week head start by starting seeds indoors rather than sowing seeds directly into the garden, which allows you to get an earlier harvest and makes for a long harvest season.  Besides, sowing seeds directly in the garden is not always practical for some crops. For example, tomatoes and peppers cannot be planted until the last frost and after the soil is warmed. If seeded in the garden at that time, tomatoes and peppers need more than a 100 days (including germination time) to produce the first fruit. In addition, newly emerged seedlings are very tender and easily killed by insects or disease or shaded by quicker-growing weeds. Starting your seedlings indoors allows an earlier start in the garden, resulting in earlier yields of certain crops, and allowing for better use of limited garden space.
• You control the environment. If you want organic plants, you have control over the soil, compost, and inputs like fertilizer.

What seeds should you start indoors?

The chart below was adapted from the Virginia Cooperative Extension Publication 426-316 and provides a list of plants recommended for starting indoors.

Plant Production Chart
Crop	Days to Emergence	Optimum Germination Growth Range (º F)	Number of Weeks to Transplant
Broccoli	3-10	65-85 º	5-7
Cabbage	4-10	50-85 º	5-7
Cauliflower	4-10	50-85 º	5-7
Celery	9-21	50-65 º	10-12
Cucumber	6-10	65-85 º	4 (peat pots)
Eggplant	6-10	65-85 º	6-9
Lettuce	6-8	50-65 º	3-5
Melons	6-10	65-85 º	3-4 (peat pots)
Onion	7-10	65-85 º	8
Parsley	15-21	50-85 º	8
Pepper	9-14	65-85 º	6-8
Squash	4-6	65-85 º	3-4 (peat pots)
Tomato	6-12	65-85 º	5-7

Seeds

The first general rule is to start with good seed. Buying seeds from a reputable supplier will help to ensure good germination. If you buy at your favorite garden store, check the date on the seed package to ensure that the seeds are fresh. As seeds get older, the germination rates decrease.

Factors Affecting Germination

The factors that affect germination and seedling growth are moisture, temperature, oxygen, and light.

Moisture (water): The first step in the germination process is the seed’s absorption of water. A continuous supply of moisture without fluctuation in the growing medium is important to ensure germination.

Temperature (heat): Some seeds will germinate over a wide range of temperatures, whereas others require a narrow range. Many seeds have minimum, maximum, and optimum temperatures for germination. For example, tomato seeds have a minimum germination temperature of 50º F and a maximum germination temperature of 95°F, but an optimum temperature of above 80°F. How fast seeds germinate is affected greatly by soil temperature.  For example sweet pepper seeds will germinate in 9-14 days when the soil temperature is in the optimal range of 65-80º F. At 55-65º the time to emergence is 21-28 days.

When germination temperatures are listed on the seed packets or in seed catalogs, they are usually the optimum temperatures unless otherwise specified. Generally, a range of 65ºF to 75ºF is best for most plants. This often means that your germination flats may have to be placed in a heated area or on heating mats to maintain that optimum temperature. Remember this is soil temperature, not ambient or air temperature.

 

Oxygen: All viable seeds breathe. Their respiration rate increases dramatically during germination; therefore, the growing medium must be loose and well-aerated. If the soil is too wet or compacted, the oxygen supply during germination is reduced, and germination can be severely retarded or inhibited.

Light: Light can either stimulate or inhibit germination, depending on the plant. Although most seeds germinate in the darkness, a few plants, such as lettuce and parsley, require light, whereas others, such as tomato and peppers, germinate best in the dark. Seed catalogs and seed packets generally indicate light requirements. I always take a minute to read the seed packet or seed catalog to determine the light requirements for germination.

Transplant Containers: You can use any type of container which will hold a soil mix and are about 3 inches in depth, and capable of holding a minimum of 3 tablespoons of soil. The container must have holes in the bottom for drainage. There are lots of possibilities for containers —  recycled yogurt cups, cottage cheese containers, cut off milk cartons, discarded aluminum trays, and recycled cell packs. New cell packs, peat pots, or peat pellets can be purchased at garden centers, farm supply stores, or hardware stores, and are usually available (in season) in large box stores or online sources. I have a gardening friend that creates his own transplant containers from strips of newspaper. Peat or paper pots that break down in the soil are particularly good for raising seedlings that do not transplant easily —  such as cucumbers, squash, and watermelon.

If you are recycling containers that have been previously used for growing plants,  be sure to sterilize them before reuse. Wash them thoroughly with hot water and soap and then soak for 10 minutes in a solution of 1 part household bleach and 9 parts water. After sterilizing them, rinse well and let dry before use.

If you are using recycled non-plant containers such as plastic cups, remember to punch or drill a hole in the bottom of the container for drainage.

Growing Medium

A good germinating medium should be fine and uniform, well aerated, and loose. The medium should be free of insects, disease organisms, and weed seeds. It should also be of low fertility and capable of holding and moving moisture.

Artificial soil-less mixes offer all these desired qualities. The basic ingredients of such mixes are usually shredded sphagnum peat and fine grade vermiculite, both of which are generally free of weed seeds and insects. Avoid using plain garden soil or regular potting soil, as it tends to crust and harden, making it difficult for delicate seedings to “break through.” In addition, ordinary garden soil may contain weed seeds and diseases that may contribute to damping off.

Once the seedlings have emerged and developed one or two sets of true leaves, you can transplant them into a slightly larger container with a coarser seedling-growth mix.

When to sow your seeds

In November 2023 the USDA released a new Plant Hardiness Zone map. The Charlottesville area is now in Zone 7b. Read more about the change in this month’s Edible Tasks article. The dates below have been updated to reflect the area’s new zone.)

You have rounded up all your material: containers, soil and seed. The next thing to be determined is when to plant your seeds. The most critical date to keep in mind is the last average frost date in your area. In our area in central Virginia, it is April 5th – 15th. For most crops, that date is used to calculate your indoor seed-starting date.

Let’s look at tomatoes, for example. Tomatoes cannot be set outside until the last average frost, April 15th. Tomato seedlings require about 5-7 weeks after sowing to be ready for transplanting, so counting back 6 weeks from our average last frost date of April 15th, I arrive at my targeted date for indoor sowing — around March 1st.

It’s a different story with certain “cold weather” crops, such as cabbage and broccoli.  For example, in our area we can start to transplant cold weather crops into the garden around the second week of March, i.e., March 15.  If I know that cabbage seedlings require an average of 5 to 7 weeks to be ready for the garden, I assume about 6 weeks indoor growing time. Then I count backwards 6 weeks from March 15th and come up with Feb 2 as my targeted date for sowing cabbage seeds indoors.

The varying timings required by different crops could give you a headache. For this reason, I have found that making a schedule for different crops can be a very useful tool. The Virginia Cooperative Extension’s Home Garden Vegetable Planting Guide lists outside planting dates for crops in Virginia. Its map hasn’t been updated yet, so use the new map to find which set of dates to use for your location.

There are many online sources that provide information on temperature and time requirements for growing transplants. Remember, these are only guidelines. In general, the length of time is based on optimum germination temperature. You may need to adjust the time requirement to fit your specific growing environment. Also, the charts are guidelines, and there are always exceptions. For example most charts suggest 6-8 weeks to grow pepper transplants, and I have found that works well for most peppers; however, if you are into growing hot peppers, 6-8 weeks usually is not enough, especially for capsicum chinense pepper types. Chinense varieties include super-hot peppers such as Habanero, Scotch bonnet and Bhut Jolokia (Ghost). These super-hot varieties, because of their long germination periods and slower growth rates, can take anywhere from 8-15 weeks to grow transplants, again depending on the various environmental conditions. Over the years I have learned to read the seed packets for instructions on growing times. The information on the seed packets is a must-read.

 Steps in Planting Seeds Indoors

Now that you’ve figured out when to plant your seeds, you can start sowing seeds. Remember that the containers for starting seeds should be sterile and free of harmful chemicals.

• Pour the germination medium into a clean bucket or small tub. Add water to the germination medium so that it is saturated like a sponge. If you squeeze a handful of the medium and water runs out it is too wet, so add more medium.

• Fill the container to within ¾ inch of the top with the growing medium. Make sure the container has adequate drainage.

• Add two to three seeds per pot or cell, unless the seed is old or has a low germination rate. In that case, add a few more seeds.

• Cover the seeds with the germination medium or horticultural vermiculite. How much to add?  Follow the depth instructions on the seed packet.

• Label the containers.  It’s useful to note when you planted the seeds and how long they took to sprout. Keep a journal of what you did and when you did it. Your observations will be critical in fine-tuning your planting strategies and schedule in the years ahead.   That’s the way to achieve success in producing vigorous, sturdy, short, dark green transplants.

• Water each container very lightly to ensure the seeds have made contact with the soil. A misting bottle works well.

• Cover the container(s) with plastic or cling wrap and then place in a warm area or on a heat mat. This keeps the seeds warm and moist to increase germination rates.
  

  Plastic cover over planting container

• Each day check for germination. Once the seeds have sprouted, immediately remove the plastic wrap or plastic dome and move into strong light. A south window sill is a good place, but remember to give the pots/containers a  turn each day so the plants grow straight instead of bending towards the light.  The use of fluorescent lighting is recommended to avoid spindly plants. If you are using fluorescent lighting, position the lights 3 to 6 inches above the seedings. Closely monitor the plants, and adjust the light up as the seedlings increase their height. The lights should be kept on 12 to 16 hours per day. Regular light bulbs or incandescent bulbs are not recommended because they produce too much heat in relation to the light given off. They also lack the blue spectrum light that keeps seedlings stocky and dark green. Keep the soil moist and maintain air temperature of 65-70º F.

Watering and Damping Off

Keep the soil moist while the seeds are germinating. I recommend a a spray bottle, which allows you to mist the surface gently without washing away the potting mix. If the containers are sitting in a tray, you can simply add water to the tray, where it will move upwards into the growing medium. Be sure to drain excess water that remains or accumulates in the tray  to keep the roots healthy. The planting medium should be kept moist, not wet. If the soil is too wet you run the risk of retarded root growth that often leads to disease problems, such as damping off.

Damping Off  is a plant disease caused by several fungi, including molds such as Phytophthora, Pythium, Fusarium and others. These fungi occur in all soils and are water-loving organisms that thrive in wet, cold, or poorly drained soils.

Size does matter — seedlings should not be started in large pots, because large containers hold more water, more than the small seedling can use, making an ideal environment for damping-off. It’s recommended to start your seeds in small containers first, and transplant them into larger containers once the seedlings have germinated and developed.

A fungus in the soil can attack seeds and seedlings as they begin to germinate and grow. Pre-emergence damping-off occurs when the seed or seedling dies before it reaches the soil’s surface, whereas post-emergence damping-off occurs after the seedling emerges and grows to a height of an inch or two, causing it to wilt, fall over and die. Plants that are attacked by these fungi but do not damp-off are often stunted. A constricted stem at or just below the soil line is a sign that the plant underwent a fungus attack.

Damping-off is controlled primarily through good sanitation, high quality planting material, and proper cultural and environmental controls. Damping-off is worse when soil is wet or compacted.

Thinning Out

As soon as your seedlings have developed at least one set of leaves, you need to provide them more room. If you have planted them in individual pots or cell packs, you can take a pair of sharp scissors and simply snip the smaller plants, leaving only one plant, the strongest and healthiest plant. A second option is to gently separate the small plants with a clean knife or plant label. My favorite tool for separating seedlings is a small cocktail fork. Gently ease the seedlings apart, being careful to avoid tearing the roots in the process.  Then repot the seedlings in a slightly larger pot. Handle small seedlings by their leaves; those small, thin stems break easily. Failure to thin or transplant crowded plants can result in spindly seedlings that may not develop properly,

Fertilizing

The seed will provide sufficient nutrients until the seedling develops its first set of true leaves. The true leaves are a sign that the seedling has used up its store of nutrients in the seed and will require outside fertilization. Once the first true leaves appear, water with a half-solution of fertilizer; you can use a water-soluble all purpose plant food or organic fertilizer such as fish emulsion. Fertilize only once a week. Water as needed the rest of the week. As the seedlings grow, gently brush them to and fro with your hand to “mimic a gentle breeze.” This will help strengthen the stems and prevent excessive stem elongation (leggy plants).

Hardening-off

Before transplanting seedlings into the garden, it’s important to condition the plants for outdoor conditions. This conditioning is achieved by hardening the plants. Hardening is the process of gradually acclimating tender plants to the outside environment. Harden the plants two weeks before transplanting by moving them into a shaded area outdoors such as a porch or under a shrub. Then, move them gradually to sunlight for a short time during the day. Slowly increase the length of exposure time. Do not expose the seedlings to freezing temperatures or strong winds. Reduce watering, but do not let the plants wilt. After proper hardening, carefully transplant the plants into the garden.

Seeds have their individual needs. Always follow the instructions on the seed packets, as that is your recipe for success. Thanks for joining us in the Garden Shed. We hope to see you again next month.

 

Featured Image:  Gerald Holmes, Strawberry CenteCal Poly San Luis Obispo, Bugwood.org, CC BY-NC 3.0

Resources:

“Season Extension Community Gardening Guide (PDF),” USDA

“Plant Propagation From Seed,” Va.Coop.Ext. Publication Number 426-001

“Seed for the Garden,” Va. Coop. Ext. Publication Number 426-316

“Indoor Vegetable Seed Starting (PDF),” Cornell University

“Damping Off Diseases in the Garden,” University of California Agriculture & Natural Resources

“Back to Basics: How to Start Seeds Indoors,” Texas Coop.Ext.

“A Practical Guide to Using Mechanical Stimulation to Prevent Stretching in Tomato and Cucumber Transplants,” Cornell University

 

 

 

 

 

 

Praying Mantids

• February 1, 2024
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• 2 Comments

Most people are able to identify praying mantids in our landscapes and think of them as a cool beneficial insect, a “guardian against pests.” But a closer look reveals a more complicated picture. Both native mantids and non-native invasive mantids inhabit our landscape and can have a significant impact on pollinators and the ecosystems they support. 

Many refer to a member of this insect group as “praying mantis” but mantis refers to the specific genus, while the term mantid refers to a larger group of insects that appear to be praying when at rest. This creature looks quite tranquil, sitting quietly with its praying pose, forelegs upraised, camouflaged, waiting for some unsuspecting insect or other small animal to wander by. The mantid’s neck allows the head to rotate 180 degrees to scan the area. When the insect wanders by, the praying mantid quickly snags a meal, using the long spines on the upper insides of its forelegs to hold its prey. Mantids do kill harmful plant-eating pests, but as generalist, ambush predators, they also kill virtually everything else, including beneficial insects. “They just eat whatever is moving and within their reach,” said Michael Maxwell, a behavioral ecologist at National University in La Jolla, California. 

 

Identifying Invasive Mantids

The Chinese mantis (Tenodera sinensis) and the European mantis (Mantis religiosa) are the two most prevalent invasive species of mantids found in Virginia and the eastern United States. The Chinese mantid is believed to have been accidentally introduced to the U.S. in 1896 on a shipment of plants to Pennsylvania. In the 1930s, European mantid egg cases were purposely sold for garden pest control and as a biological control agent for the spongy moth, then called the gypsy moth, in the eastern U.S. 

 

 

 

 

 

 

 

After developing adult wings, the Chinese mantid can reach five inches long. Its brown or green coloration provides effective camouflage, and its wings extend the entire length of its abdomen. The European mantid is about three to four inches long and is usually greener in color than the Chinese mantid. Like many invasive species, their aggressive nature poses a threat to the native Carolina mantis (Stagmomantis carolina), which is more brown than green in color and much smaller at two inches long. Its wings cover only two-thirds of the abdomen. The larger invasive species outcompete the Carolina mantis for food and will even eat the Carolina mantis. Thus, the smaller, native Carolina mantid (Stagmomantis carolina) is seen much less frequently and is relatively uncommon. 

 

The Impact of Mantids

Scientific studies have demonstrated some of the effects of mantids on pollinators and their habitat. In a study published in 2014, Michael Maxwell found that the largest single component of the diet of the native mantid Stagmomantis limbata was honeybees, a species in decline. Maxwell and his colleagues have also documented 147 cases of praying mantids catching birds, mostly hummingbirds, which are pollinators. Maxwell noted that the mantises often sit on flowers waiting to kill insects and other prey. 

Chinese mantids are so large and abundant they consume a large number of beneficial pollinators and other native species including small birds, reptiles and amphibians as well as the smaller native Carolina mantis.  Erin E. Wilson Rankin and colleagues found that “Overall, both T. sinensis and M. religiosa fed on a diversity of diet items in old fields. Mantids preyed upon species that filled a variety of ecological roles, with the majority (>75%) of their diet being herbivores, predators and pollinators regardless of whether mantids were included as prey.”

The horticulture team at the Brooklyn Bridge Park in New York made similar findings, noting that the large Chinese mantids indiscriminately consume large numbers of beneficial insects, such as bumblebees, flower flies, butterflies, and other pollinators.   This 85-acre public waterfront park is managed as wildlife habitat with primarily native plants, using organic techniques and encouraging biodiversity through research and experimentation.  The Brooklyn team observed numerous large mantids on flowering plants in summer and fall and often found a pile of discarded monarch butterfly wings on the ground below. They also reported that the larger the mantid, the larger the prey they will eat.  And of course, the more mantids there are, the more prey they consume. Concluding that predation pressure from mantids was becoming a significant threat to many of the insects attracted to the park, the Brooklyn team has begun to mitigate the problem by selectively removing and destroying the egg cases – called ootheca – of the non-native mantids. 

Help Control Invasive Mantids

Destroying the egg cases (“ootheca”)  of the Chinese and European species before they hatch can help keep populations in check. Because the egg cases are formed in late summer/early fall, scout your landscape in winter to find the egg cases.  They can be attached to a variety of woody shrubs, herbaceous plant stems, twigs or even fence posts. Freezing winter temperatures kill any remaining adults but the egg cases provide protection.  Mantid nymphs emerge when temperatures again reach approximately 70° in the spring. 

 

 

 

 

 

 

 

 

 

Control depends on identifying which egg cases (ootheca) belong to invasive mantids. The female covers her eggs with a foamy substance that hardens into a texture similar to Styrofoam. Depending on the species, the egg case contains hundreds of eggs.  The photo guide below can help with identifying invasive versus native mantid egg cases.  The ootheca of the Chinese mantis, most commonly sighted, is puffy, round to cube shape with a foamy texture. It is ping-pong ball size and straw brown in color. The ootheca of the native Carolina mantis is elongated and slender. It is relatively smooth and has a sequence of lighter and darker brown stripes. Both the European mantis and the Carolina mantis ootheca have a similar elongated shape, but the European mantis egg case is not as flattened or as smooth in texture. The major difference is the color of the egg cases. The European mantis ootheca is solid pale brown with no striping while the Carolina mantis is greyer in color with a white midrib. The egg masses of the nonnative mantids can be crushed or cut open and submerged in water, tied up in a garbage bag or better yet, fed to chickens.  

 

Protect Native Mantids

If you find the ootheca of the native Carolina mantis, do not disturb the egg masses.  Although they are generalist predators, they are small in size and have less of an impact than the invasive mantids.

 

 

Don’t Buy the Invasive Mantids

Garden and pet stores continue to aid in the spread of the invasive species by marketing them as a form of garden pest control. Encouraging the population growth of these invasive species can be detrimental to our native Carolina mantis, as well as to our overall pollinator populations. Don’t buy invasive mantids. Let’s give our native species the opportunity to thrive without added competition. 

As North Carolina Extension Agent, Debbie Roos states, “Getting rid of the predominant invasive Chinese and European mantids egg cases annually will hopefully help reduce predation pressure and help maintain a better balance of species. It doesn’t make sense for us to create habitat for pollinators and other beneficial insects, only to let the invasive generalist predators feasting unchecked on the critters the habitat has attracted.” By controlling the nonnative mantids and by supporting our region’s only native mantid, we will maintain the balance she advocates and better manage our landscapes for biodiversity. Gardeners can think of this as “weeding insects” in much the same way we weed unwanted plants. 

  

Featured Photo:  Carolina mantid, Kansas Department of Agriculture, Bugwood.org

SOURCES and additional reading:  

“Managing Pollinator Habitat:  Reducing Invasive Mantids at Brooklyn Bridge Park,” Bella Ciabattoni, Pawel Pieluszynski,  https://www.ecolandscaping.org/03/landscape-challenges/pest-management/managing-pollinator-habitat-reducing-invasive-mantids-at-brooklyn-bridge-park/

“Bird Predation By Praying Mantises: A Global Perspective,” bioone.org/journals/the-wilson-journal-of-ornithology/pdf  (Nyffeler, Martin, Maxwell, Michael R., and Remsen, J. V.,  The Wilson Journal of Ornithology, 129(2) : 331-344)

“The Invasive Mantis Species,” Brandywine Conservancy, https://www.brandywine.org/conservancy/blog/invasive-mantis-species

“Get to know your local mantis,” University of Maryland Extension https://marylandgrows.umd.edu/2022/11/09/get-to-know-your-local-mantis/

“Challenging the Conventional Wisdom About Praying Mantids,” Debbie Roos, North Carolina State Extension, https://growingsmallfarms.ces.ncsu.edu/2023/03/challenging-the-conventional-wisdom-about-praying-mantids/

“Praying Mantids,” Gary Watkins and Ric Bessin, Student and Extension Specialist, https://entomology.ca.uky.edu/ef703

Diets of two non-native praying mantids (Tenodera sinensis and Mantis religiosa) show consumption of arthropods across all ecological roles