The Garden Shed
A Community Newsletter published by the Piedmont Master Gardeners
April 2022- Vol.8, No.4
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.
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 Edible Garden
Basil, a summer favorite of many, offers beauty and delightful fragrance in the edible garden.
Tasks and Tips
April is the time to prepare garden beds, plant cool weather crops and get the garden going.
In the Ornamental Garden
Inkberrry – A Native Evergreen Shrub
When choosing native evergreens, the choice is limited. Inkberry, however, is an attractive, adaptable, eco-beneficial shrub.
Tasks and Tips
April in the Ornamental Garden
April is prime planting season in the mid-Atlantic and a glorious time to celebrate new life in the ornamental garden.
April in the Edible Garden
It’s April and edible gardening is in full swing. The air and ground are warming, buds are fattening and if you did some cool weather vegetable planting in March, you may soon be enjoying some early garden produce. If you haven’t gotten started yet, there is plenty of time to get things going for a productive gardening season.
Bed Preparation
As mentioned in previous articles, deep tilling is no longer a recommended practice, except for new beds where loosening compacted soils and integrating organic matter can make sense.
If you grew a cover crop over the winter, let it grow as long as possible short of letting it set seed. This enables deepest root penetration and greatest photosynthetic carbon deposits in the soil. To remove it, cut it as close to flush with the soil as possible, with a string trimmer or mower. If possible, leave the residue on the ground for a couple of weeks to let roots begin to decay, then use a stirrup hoe (some call it a scuffle hoe) to cut the crowns, just below soil level. Leave the cuttings as mulch if installing transplants or add them to the compost heap if you are planting seeds. Leave the roots to decompose in the soil and smooth the surface with a rake to present a nice seed bed.
Occultation is a no-dig alternative for weed control. It involves covering beds with a black plastic tarp or landscape fabric for 4-6 weeks to starve weeds of sun and kill seeds with heat. Remove the tarp and plant transplants directly. If seeding, rake off residue and compost it.
A broadfork at work, from the video, “The broadfork – Jean-Martin Fortier – The Market Gardener’s Toolkit,”
To loosen compacted soil, drive a digging or broadfork as deeply into the soil as possible and rock it back and forth to loosen soil without destroying structure. Work your way across the beds. If adding an amendment like compost or manure, layer it on top and allow it to work into the soil during broadforking. Rake the surface smooth, and you are ready to seed.
Planting
If starting from seed, follow seed packet directions. For intensive or square foot gardening, ignore the row spacings and use seed-to-seed spacing in both directions. Goal is to space plants so that mature plants will just touch each other, helping reduce moisture and weed pressure while maximizing production for a given garden space.
Fertilization is important for best results. For guidance on what products to use and how and when to apply them, review Garden Shed article A Fertilization Primer.
According to Virginia Cooperative Extension’s Virginia’s Home Garden Vegetable Planting Guide, in Hardiness Zone 7a:
- There is still time to plant cool weather crops, including: beets, broccoli, cabbage, carrots, cauliflower, greens and lettuces, potatoes, spinach, radishes and turnips. They like it cool, however, so get them in soon.
- Late April is the earliest time to plant bush and pole beans, cucumbers, eggplant, melons, squash and tomatoes. These guys are harmed by frost, however, so check the longer-term weather forecast before setting them out or planting. Be prepared to protect them if a late frost sneaks into the region.
A Few Tips
- Where possible, rotate your crops, on a 3-4 year cycle to minimize pressure from soil borne diseases and pests.
- Maintain a journal to record crop locations, varieties planted, pest and disease issues, and growing success. You will be thankful when you plant next year.
- Plant seeds at a depth of about 2 times the seed width (not length). Moisten when planting and keep moist until germination.
Trellis. Photo: U of Minnesota Extension
- Trellises are a great way to save space and keep plants off the ground. VCE publication Vertical Gardening Using Trellises, Stakes and Cages offers guidance for a variety of space-saving plant supports.
Hardening-off seedlings. Photo: R Morini
- If you started seeds indoors, remember to harden the plants off by progressively exposing them to the outdoors for 1-2 weeks when outside temperatures are above 50 degrees, prior to transplanting.
- It is best to transplant on a cloudy day or in late afternoon to reduce shock to young plants.
- If transplanting peat pots, tear off the top of the pot to a point below the soil line to avoid wicking water away from plant roots.
- Mulching plants after transplanting or germination is a good thing but give the soil a chance to warm up before mulching to avoid slowing plant growth.
- When laying out plant locations, remember that leafy greens typically require 6 hours of sun per day while fruiting vegetables want at least 8 hours.
- Consider intercropping. Mixing different plant varieties uses space well, adds diversity to the garden environment, creates a variety of scents that can confuse pests, and attracts a broader array of beneficial predators, helping reduce pest damage.
Swiss Chard. Photo: Courtesy of Pixabay
- If you would like to extend the harvest season for your greens, consider chard. Chards have a lower tendency to bolt and can withstand summer heat longer than most other greens. In addition, rainbow chard makes a pretty presentation in the garden.
- Should a surprise late frost threaten your warm weather crops, a row cover can save the day. Review the Garden Shed article: Row Covers: A Garden Season Extender with Benefits for materials and construction tips.
- It isn’t too late to plant asparagus or strawberry patches. For guidance on starting asparagus refer to the Garden Shed article Spear into Spring with Asparagus,and the VCE publication Asparagus, which specifies recommended cultivars for Virginia.
New strawberry bed: Photo Ralph Morini
- For strawberries and other small fruits check out the VCE publication Small Fruit in the Home Garden.
- If you are planning a home orchard, check out the VCE publication Tree Fruit in the Home Garden for help in site selection, tree selection and care for many popular fruits.
- Best tree planting techniques for both bare root and root ball trees is detailed in Planting Trees Correctly from the Clemson Extension.
- If you are curious about the weeds in the garden or its surroundings, for elimination or edibility, VCE’s Weed Identification Guide is a good resource.
I hope you find this information helpful. Comments on content are welcome. In any case, enjoy your garden and please come back next month.
SOURCES:
Cover photo: Compost: Photo: Ralph Morini
Inkberrry – A Native Evergreen Shrub
Ilex glabra, commonly called inkberry or gallberry holly, is an evergreen shrub native to the eastern and south-central U.S., including the coastal region of Virginia and its southeastern counties. It is not native to the Piedmont Virginia region. It is a member of the botanical family Aquifoliaceae (holly). Inkberry is often used as a native evergreen alternative to boxwood and to other nonnative evergreens, such as Chinese, Japanese, and European hollies, and the more compact cultivars of Chinese juniper. A 1991 article in Arnoldia by Dirr and Alexander describes the appeal of Ilex glabra:
As part of the native plant movement, and with its superior adaptability, Ilex glabra is a natural for increased landscape use. Recent emphasis on wetland mitigation is another plus for the species.
ADAPTABILITY
Ilex glabra Photo: Sarah Bingham
Although commonly found in moist to wet soils, this highly adaptable shrub does well in home landscapes. It can thrive in conditions ranging from full sun to moderate shade; from wet to dry sites; and from sandy soils to clay. It likes an acid to neutral soil with a pH range of 3.5-6.0; it has good salt tolerance. When the earth is too alkaline, inkberry is prone to chlorosis, or a yellowing of the foliage. The straight species is generally hardy in USDA Hardiness Zones 5-10.
CHARACTERISTICS
Inkberry has an upright, rounded habitat developing multiple trunks. Stems arise from heavy, tuberous rhizomes which often produce suckering. Oval, alternate leaves are a shiny dark green on top, with undersides that are duller and lighter. Leaves have a smooth edge except near the top where there are several teeth. The shrub tends to become more open and leggier as it grows to a mature height of 5-10’ and a width of 5-8’. Many consider this legginess to be one of the species’ drawbacks, and cultivars have been developed to improve fullness. These cultivars will be discussed in a later section. Inkberry may be propagated from stem and root cuttings, or from suckers.
BERRY PRODUCTION
Ilex glabra ‘Compacta’ berries Photo: Courtesy of Missouri Botanical Garden
Flowers are dioecious, meaning that individual flowers are either male or female, and only one sex is found on each bush. Both male and female hollies are required if berries are desired. The flowers are not self-fertile and are pollinated by bees. If pollination occurs between male and female plants, flowers are followed by pea-sized, jet black, berry-like drupes which mature in early fall. Female shrubs are common in nurseries, but it is difficult to find male cultivars, or male inkberry straight species.
Kim Eierman of EcoBeneficial discussed the problem of finding male inkberry cultivars in the nursery trade:
Named cultivars, like ‘Shamrock,’ ‘Nordic,’ ‘Nigra,’ ‘Densa’, ‘Compacta,’ ‘Cape Cod,’ etc., are one sex – and all of those cultivars are female. The only confirmed male cultivar that I and the Holly Society of America are aware of is ‘Pretty Boy.’ I have seen that cultivar offered for sale during one season at one nursery (which is no longer selling it). ‘Nordic’, often listed as a male, is actually a female.
In her article, “Looking For Mr. Goodbar—The Quest to Find Male Native Plants,” Eierman points out that this is a problem for many native species, and provides a list of other dioecious shrubs and trees.
ECO BENEFITS
Although the berries are not considered ornamentally impressive, they are a good food source for wildlife. Birds that are attracted to the berries include bobwhite quail, wild turkey, and many songbirds such as bluebirds, brown thrashers, and hermit thrashers. Opossums, racoons, and coyotes will also eat the berries when food is scarce. Deer sometime feed on the foliage; it is not attractive to rabbits. Inkberry also provides good winter cover for wildlife.
Inkberry is a larval host plant for the Henry’s elfin butterfly (Callophrys henrici) which appears from February to May and has one flight. The adult Henry’s elfin butterfly feeds on the nectar from inkberry flowers. Inkberry is also larval host to Celastrina idella, the holly azure butterfly. Other adult butterflies and bees are attracted to the blossoms as well. The specialized native bee, Colletes banksi, forages solely on holly flowers.
Gallberry honey is a highly rated honey produced from bees feeding on inkberry flowers. This honey is locally produced in certain parts of the southeastern U.S. Beekeepers release bees from late April to early June to coincide with inkberry flowering time.
PRUNING
Most evergreen pruning, which includes inkberry, is done for corrective reasons, so seasonal timing is usually not as important as it is for deciduous species. Pruning during dormancy, i.e., late winter/early spring (February-March) is the most common practice and will result in a vigorous burst of spring growth. If you don’t have male inkberries, or you are not concerned about berry production, this is a good pruning schedule.
If you are interested in berry production, however, there are other pruning options to consider. Inkberry blooms on old wood, meaning flower buds for next year’s blooms form during the current growing season. The buds are carried over through winter on last year’s growth, the old wood. If you prune male shrubs in late winter/early spring, you’ll cut off at least some of the flowers needed for pollination. In this case, you may want to prune male shrubs right after flower bloom. For female shrubs, as flowers finish blooming, those that were pollinated set fruit; pruning in midsummer will sacrifice some berry production. If you prune in late winter/early spring, you’ll cut off flower buds. Choose your schedule knowing that pruning in either period will reduce berry production. It is likely that at some point pruning will be beneficial, and you’ll need to make a choice.
Maintenance pruning is usually needed to address legginess in the species. As the plant matures and becomes thin, remove up to one-third of the branches to their points of origin in early spring. Deep pruning means taking a mature shrub down to crown level for a total makeover. If an inkberry needs rejuvenation, i.e., it’s spindly and has lost lower stems and foliage, cut it down to 1-1.5’ high in early spring when it is poised to push out new growth. This will give time for a strong flush of growth to harden off before winter.
CULTIVARS
The following is a list of inkberry cultivars, along with brief information on how the original cultivar stock was developed. The information on cultivar origins is from a 1991 article by Michael Dirr and John H. Alexander III published in Arnoldia. It is interesting to note how long these cultivars have been in the trade. Although they haven’t “solved” the legginess characteristic of the species, some offer a denser form, a somewhat improved retention of lower branches and foliage, and more compact forms better suited to small spaces. Two white-berried forms are native to the Coastal Region of the eastern U.S.: Ilex glabra forma leucocarpa, and Ilex glabra f. leucocarpa ‘Ivory Queen’. Although interesting, they don’t seem to be commonly available in the trade.
‘Compacta’
Ilex glabra ‘Compacta’ Photo: Spring Meadow Nursery
Selected in 1937 from a block of seedlings planted from seed collected in the New Jersey pine barrens. This compact plant grows 3-4’ tall and 4-6’ wide in a tight oval to rounded habit. As noted by Dirr and Alexander: “Like the species, it becomes leggy at the base and loses a portion of the lower foliage, but if pruned in a timely and artistic manner, it will remain a handsome plant.” Thick dark green leaves fade to olive green in winter. Hardy in USDA zones 4-9.
‘Densa’
Ilex glabra ‘Densa’ Photo: Spring Meadow Nursery
This cultivar was selected from a batch of 500 seedlings in 1938 for its oval to round, uniform outline with upright branches and leathery dark-green leaves. This mid-sized shrub grows 4-6’ tall and wide. Its leaves are described as wider and rounder than those of ‘Shamrock’. Hardy in USDA zones 4-9.
‘Nigra’
Ilex glabra ‘Nigra’ Photo: Wikimedia Commons, David J. Stang (CC BY-SA 4.0)
Ilex glabra ‘Nigra’ leaves Photo: Randy Harter (CC BY 4.0)
This larger cultivar grows 6-10’ tall and wide. Foliage color is a dark green. Older plants may be renewed by heavy pruning as lower branches lose foliage with time. Hardy in USDA zones 5-9.
Ilex glabra ‘Chamzin’ NORDIC
Selected out of 2,000 inkberry seedlings growing in a nursery field, it was noticed for its distinct broad pyramidal growth habit and dark green foliage. Its leaves are somewhat larger than the species. It grows 3-4’ tall and wide and is less likely to sucker. Hardy in USDA zones 3-9.
‘Shamrock’
Ilex glabra ‘Shamrock’ Photo: Wikimedia Commons, David J. Stang (CC BY-SA 4.0)
This cultivar was selected in 1977 from a block of approximately five hundred seedlings for its compact habit and bright, glistening new green foliage that overlays the previous year’s mature dark green foliage. It grows to 3-5’ tall and wide, with upright branches. Its rounded, compact habit may become leggy with age. Hardy in USDA zones 4-9.
Ilex glabra ‘Shamrock’ Young Form Photo: Jim Robbins (CC BY-NC-ND 4.0)
DWARF CULTIVARS
Ilex glabra GEMBOX Photo: ‘SMNIGAB17’
USPP 27,554; CBR 5629
GEM BOX® is about 2-3’ tall and wide with a round habit and petite foliage. New growth in spring has a reddish tip. Hardy in USDA zones 5-9.
Ilex glabra STRONGBOX Photo: ‘ILEXFARROWTRACEY’
USPP 30,147; CBRAF
STRONG BOX® is about 2-3’ tall and wide with leaves that are a little bit broader than GEM BOX®. Hardy in USDA zones 5-9.
PLANT VIRGINIA NATIVES CAMPAIGN
This campaign is an effort to help Virginia gardeners identify plants native to their area. Refer to the article in this month’s newsletter, “Coming to a Garden Center Near You,” for more information. For inclusion on the list of recommended plants, cultivars of straight species have been vetted to ensure they are ecologically viable, meaning their leaves and flowers contribute to the food web and do not negatively alter insect behavior. The inkberry cultivars native to southeastern counties of Virginia are on the list of recommended plants: ‘Shamrock’, ‘Compacta’, ‘Densa’, and ‘Nigra’.
PESTS AND DISEASES
In general, inkberry is a disease- and pest-resistant plant. It is susceptible to chlorosis (yellowing of leaves) in high pH (alkaline) soils. Leaf spot is an occasional problem. Spider mites may appear, especially in dry conditions. This shrub may also be prone to Phytophthora root rot; look for resistant alternative species if this disease is in your area. Branches are prone to breakage under snow or ice load. It has a high flammability rating.
HOW TO USE IN THE LANDSCAPE
In foundation plantings, inkberry is often used as an evergreen substitute for boxwood, especially in areas where boxwood blight is prevalent, or for other nonnative evergreen shrubs. Remove suckers from inkberry if spreading is not desired. Plant groundcovers or low perennials in front of inkberry to add fullness and to hide sparsely leaved lower stems. When used as a hedge, inkberry’s suckering tendency can be used to advantage. You can also trim the hedge to a desired height. Inkberry is a good addition to native pollinator corridors, wet areas of the landscape, and naturalized areas. Dwarf varieties, such as GEM BOX® and STRONG BOX®, can be used in containers if they are given sufficient water.
SUMMARY
Although naturally found in moist to wet areas, inkberry is known for its adaptability to different levels of moisture and sunlight, and soil type. Although current native plant enthusiasts may view inkberry as a “new” native plant choice, it has been in the trade for a considerable amount of time. Inkberry is a good native plant alternative to boxwood, especially in areas where boxwood blight is prevalent, and to other nonnative evergreen species. Cultivars have been developed to address the tendency of the species to thin out and become leggier as it matures. Many of these cultivars will still benefit from maintenance pruning to promote fullness. For fruiting, male inkberries are required; unfortunately finding them in the trade is a challenge. Inkberry is an attractive, adaptable, eco beneficial native choice that deserves strong consideration as a landscape addition.
SOURCES
Feature Photo: Ilex glabra ‘Shamrock’, Courtesy of Missouri Botanical Garden
“Ilex glabra – The Inkberry Holly,” Dirr and Alexander, Arnoldia (1991)
“How Do I Find a Mate for My Inkberry?” Kim Eierman, EcoBeneficial!
“Looking for Mr. Goodbar – The Quest to Find Male Native Plants,” Kim Eierman, EcoBeneficial!
“Native Plant Profile: Ilex glabra,” Maryland Department of Natural Resources
“Ilex glabra,” Floridata
“Ilex glabra,” NC State Extension
“Ilex glabra,” Missouri Botanical Garden Plant Finder
“Ilex glabra ‘Compacta’, Missouri Botanical Garden Plant Finder
“Ilex glabra ‘Chamzin’ NORDIC,” Missouri Botanical Garden Plant Finder
“Ilex glabra ‘Shamrock’, Missouri Botanical Garden Plant Finder
“Ilex glabra f. leucocarpa,” The Dawes Arboretum
“Ilex glabra f. leucocarpa ‘Ivory Queen’, The Dawes Arboretum
“Native Bees: These Bees Plastic-Wrap Their Brood Cells,” Dickinson County Conservation Board, IA
“Celastrina idella,” Butterflies and Moths of North America
“Callophrys henrici,” Butterflies and Moths of North America
“American Holly- More Than Just a Holiday Decoration,” The Garden Shed
“What do var., ssp., subsp., forma, and f. mean? Capturing California Flowers
“Phytophthora Root Rot of Trees and Shrubs,” Missouri Botanical Garden
“Boxwood Blight Alert,” The Garden Shed
April in the Ornamental Garden
April is prime planting season for gardeners in the mid-Atlantic. In fact, this can be our busiest month as we contend with spring cleanup, dividing, transplanting, weeding, and other spring gardening chores. The bright, sunny days and warm spring breezes this month are perfect for working outside and we can be lulled into thinking cold weather is behind us. But it’s important to stay vigilant for sudden dips in night-time temperatures that can result in deadly overnight frosts.
The average last spring frost in Albemarle County (USDA Zone 7a) generally occurs between April 15 and April 25. If a frost is forecast, cover tender new growth to protect it from frost damage. Use a row cover, an old sheet, cardboard, or even layers of newspaper for this purpose. Remove the coverings the next morning so that you don’t inadvertently “cook” your plants as daytime temperatures warm up.
As daffodils and hyacinths finish blooming, cut the flower stalks all the way back to the ground but leave the foliage in place to die back naturally. This allows the plant to focus on storing energy for next year’s blossoms rather than on developing seed heads. The foliage may look a bit messy, but don’t braid or tie it up because this may interfere with photosynthesis, which could affect next year’s blossoms.
If spring-flowering bulbs such as daffodils, snow drops, or crocus have become crowded and didn’t produce as many flowers as in past years, that may mean they need to be divided. The ideal time to divide these bulbs is after the foliage has died back, which may be June or July. Mark the location of the flower clump now while you can still see the green or yellowing foliage. This will help you remember where the clump is located, plus it will remind you not to plant something else in the same spot. Make a note to dig up and separate the bulbs once they are dormant. Either replant them immediately or store them in a cool, dry, well-ventilated place and replant them in the fall.
Top dress established ornamental flower beds with an inch of compost. For new flowerbeds, work compost or aged cow manure into the loosened soil before you start to plant. A slow-release fertilizer and lime may also be added to the soil if a soil test indicates the need for either.
Hairy bittercress. Photo: Leslie J. Mehrhoff, University of Connecticut, Bugwood.org, CC BY 3.0
Remove broadleaf winter weeds before they set seed. These cool-season weeds include chickweed, deadnettle, hairy bittercress, and henbit. They germinate in late summer or early fall, overwinter in the landscape, and produce flowers and seeds in spring. You can suppress their growth in your flower beds by applying a layer of mulch over bare ground or planting a dense ground cover. Weed identification information and photos are available on a number of extension websites such as Virginia Tech (weedid.cals.vt.edu), University of Missouri (weedid.missouri.edu), or the University of Illinois (weeds.cropsci.illinois.edu).
Divide fall-blooming perennials, such as asters (Symphyotrichum species), chrysanthemums (Dendranthema), shasta daisies (Leucanthemum), black-eyed Susan (Rudbeckia), ornamental grasses, sneezeweed (Helenium), false aster (Boltonia), and bee balm (Monarda). Most perennials benefit from being divided every three to five years on average, but if you’re not sure if a plant should be divided, here are a few questions to ask yourself:
- Is the plant not producing as many flowers as in previous years?
- Has it outgrown its assigned space in your landscape and is it crowding other nearby plants?
- Is it alive around the edges of the crown but dead in the center?
- Does it seem less vigorous in general?
- Do the stems in the center of the plant have smaller leaves?
- Are the inner flower stalks weak or flopping over?
If the answer to any of these questions is yes, then the plant probably needs to be divided. Try to complete this task at least six weeks before hot weather sets in so that the divisions have ample opportunity to become well established.
Another reason to divide perennials is to increase air circulation, which helps control fungal diseases. For example, Monarda fistulosa (or wild bergamot) is valued for its highly aromatic flowers that attract pollinator insects such as bees and butterflies, but it is subject to powdery mildew. By dividing this popular native plant every 3 years to improve air flow and providing it with moist, well-drained soil, a sunny site, and destroying all infected foliage, can help keep this common fungal problem under control.
Before digging holes for new plantings, keep in mind the ultimate size of each plant. Also, group plants together according to similar needs for water, nutrients, and sunlight. Remember to update your gardening records indicating the location of your new plantings.
Pinch back chrysanthemum foliage this month when the plants are about 4 inches high. Pinching makes the plant bushier, sturdier, and more wind-resistant later in the season. Tall aster species also benefit from being pinched back for the same reasons. False sunflower (Heliopsis helianthoides) is another plant that benefits from being pinched back in spring to reduce the plant’s height.
At this time of year, garden centers are overflowing with the best selections of landscape plants. Shop for azaleas and rhododendrons while they are in bloom to ensure you like the color and that the color harmonizes with your other landscape choices. This is particularly important if you are adding new plantings to an established landscape. Some pink selections, for example, have an orange or coral undertone that may clash with other spring-blooming species located nearby. Tip: Azaleas generally look best planted as a grouping in part sun or filtered shade and acidic, well drained, organically rich soil with a pH of 5.0 to 6.0.
As you select new plantings for your garden, avoid plant species that are potentially invasive in this area of Virginia. Look for native plants that minimize maintenance, require less water, and increase habitat, particularly for beneficial insects. A number of excellent native plant resources are available, such as the Virginia Native Plant Society’s website at vnps.org, the Albemarle County Recommended Native Plants website at webapps.albemarle.org/nativeplants, or the Virginia Department of Conservation and Recreation’s Natural Heritage Program at dcr.virginia.gov/natural-heritage. Also, explore back issues of The Garden Shed for a number of articles on native plants suitable for our area.
Buy annual bedding plants such as begonias, petunias, pentas, geraniums, or marigolds while selections are plentiful. Choose healthy plants with well-developed root systems that are not too large for their pots. Don’t plant them, however, until the danger of frost is past, night-time temperatures are consistently above 50° F, and soil temperatures are above 60° F. Depending on the weather, that may be toward the end of April or even early May. If you just can’t wait that long, be prepared to protect those tender seedlings from frost if temperatures threaten to turn chilly.
If you prefer to start bedding plants indoors from seed rather than buy transplants from a garden center, you can still sow the seeds during the early part of April if you didn’t get around to it in March. Don’t forget to harden off tender seedlings before planting them outdoors. For the new or inexperienced gardener, Virginia Cooperative Extension (VCE) Publication 426-001, Plant Propagation From Seed, provides good information on sowing seeds.
Plant some everlastings in your ornamental garden this spring. The term “everlasting” refers to a flower, seedpod, or other plant part that can be dried or preserved without the loss of its shape or color. Everlastings are used in dried flower arrangements, wreaths, bridal bouquets, and many craft projects. In addition to strawflower (Helichrysum), baby’s breath (Gypsophila paniculata), and statice (Limonium), all of which are easily preserved, try experimenting with other flowers such as: Bells of Ireland (Molucella laevis), cockscomb (Celosia), or globe amaranth (Gomphrena).
Don’t move your houseplants outside until night-time temperatures consistently stay at 50° F or higher. Depending on the weather, this may not happen until very late April or in May. Place them in a shaded area on a porch, patio, or under a tree or wherever they can gradually acclimate to the increased light levels. Moving a houseplant from indoors directly out into a sunny location can burn the leaves, which will severely damage the plant.
Before you move your houseplants outdoors for the summer, repot any that are rootbound. You can tell a plant is rootbound if:
- The roots are growing through the pot’s drainage hole or can be seen on the surface of the soil.
- The plant is either growing very slowly or has stopped growing even when fertilized.
- The lower leaves are turning yellow, which may be a sign of a nutrient deficiency.
- The potting mix is drying out faster requiring more frequent watering.
- The plant appears to be too large for the pot.
To repot a houseplant, choose a container that is only slightly larger in size. If the pot is too large, the soil can stay moist for too long, which can cause root rot. For additional information on houseplant care, see Virginia Cooperative Extension Publication 426-100, Indoor Plant Culture, or see the University of Maryland Extension’s publication on Potting and repotting Indoor Plants.
Boxwood leafminer damage. Photo: Jim Baker, North Carolina State University, Bugwood.org, CC BY-NC 3.0
With the arrival of spring comes the start of the annual battle with insects, such as leafminers. Leafminers are the larvae of insect species that burrow within a leaf and devour its inner layers, leaving either winding, serpentine tunnels or brownish blotches, depending on the plant and the leafminer insect species. Both the larvae and the damage they cause are generally undetectable until after it is too late. Winding tunnels caused by sawfly insects are commonly found on the foliage of columbine (Aquilegia), hollies (Ilex), and roses. The damage doesn’t actually harm the plant, but it can look unsightly. It’s usually sufficient to snip off the damaged leaves or simply ignore the problem if it’s not too pervasive. Other leafminer insect species cause blotchy or blistery looking damage, which is more destructive to plants such as boxwood. (See University of Maryland Extension publication for a description of and management options for Boxwood Leafminer on Shrubs). To learn more about Leafmining Insects, see Colorado State University Extension Fact Sheet No. 5-548.
Inspect Azaleas for lacebugs (Stephanitis pyrioides), which overwinter as eggs on the underside of infested leaves, then hatch out in spring. They damage foliage by piercing plant cells with their mouthparts and sucking the leaf dry. Look for white or silvery looking stippling on the upper leaf surface. The damage is unsightly, but it won’t kill the plant.
Slugs and snails start making their appearance in spring, particularly if the weather has been cool and wet. One very effective control method is to pick them by hand, or with tweezers if you’re squeamish, and drop them into a pail of soapy water to drown. For more information on how to control slugs and snails, see the University of Maryland extension’s publication on Slugs and Snails on Flowers.
Check emerging Irises for diseases or borer damage. Leaf Spot is one of the more common fungal diseases of irises. For information on symptoms and controls of this disease, see VCE Publication 450-600, Iris Leaf Spot. Iris borers are another common problem. The larvae of this pest feed below the soil level on the rhizomes. Feeding damage is sometimes not apparent until the plant dies or the leaves wilt. Inspect young iris foliage for notches that are cut in the edges of center foliage and slimy frass. This is the point where the borer enters the leaf. If you detect the presence of a borer caterpillar inside the leaf, crush it with your fingers. Once this voracious pest burrows to the rhizome, it will hollow it out and then proceed to other rhizomes. Bacterial soft rot often follows borer damage and can destroy an entire bed of Irises. The best way to control this pest is to burn the foliage or dispose of all dead or damaged leaves in the trash in fall.
And speaking of pests, apply deer repellent as vulnerable plants emerge in spring or take other preemptive measures to discourage deer browse on tender, succulent new plant growth.
Invasive watch: Callery or Bradford (Pyrus calleryana ‘Bradford’) is in bloom this month. This invasive species and other ornamental pears started out as popular landscape trees in the 1960s and are now considered invasive in 29 states. The trees often produce fertile seeds that are easily spread by birds. The seedlings can easily establish in disturbed areas, where they are contributing to the shrinking biodiversity of our urban forests. Control trees less than 6’ tall with a higher-than-usual (3-4%) concentration of foliar spray. Foliar sprays are effective from when leaves emerge in spring until just before they begin to develop fall color. For detailed information on how and when to eradicate this invasive species, including tree trunk methods in the fall, see the Blue Ridge Partnership for Regional Invasive Species Management’s Bradford Pear Fact Sheet.
Feature photo of spring-blooming Phlox divaricata: Pat Chadwick
Upcoming Events
Tree Stewards’ Spring Tree Sale
Saturday April 9, 2022, 10:00 a.m. to 2:00 p.m. at the Virginia Department of Forestry, 900 Natural Resources Drive, Charlottesville. Masks are recommended but not required. For a list of the trees available for sale, click here. These young trees are offered at prices of $5.00 to $15.00.
Arboretum and nature trail walks will be available on the grounds of the Department of Forestry during the sale. Walks will be either on lawns or cleared trails over generally flat terrain. Find out more⇒
The Spotted Lanternfly Is About to Hatch. Learn to Identify and Help Control This Destructive Invader
–free presentation by Virginia Cooperative Extension
April 12 @ 6:30 pm – 7:30 pm at The Center at BelvedereThe Spotted Lanternfly is an invasive pest detected in Albemarle County in July 2021. This insect poses a significant threat to our area vineyards, orchards, and hops yards. In addition, masses of these insects can cause significant damage to homeowners’…
Charlottesville Area Tree Stewards’ Spring Tree Identification Presentation (Zoom)
Tuesday evening, April 19, 7:00 to 8:30 p.m. Register here.
Blue Ridge PRISM’s Spring Quarterly Meeting, a free online event
April 21, 11:30 — 1:00 pm
How do invasive plants and herbicides affect native pollinators? Celia Vuocolo, Private Lands Biologist with Quail Forever will discuss how invasive plants affect our native pollinators. Joining her will be Blue Ridge PRISM’s program director Beth Mizell who will explore the exposure pathways of herbicides and how they affect pollinators. They will also cover strategies on how to mitigate the possible impacts of herbicides to pollinators during invasive plant management. You can submit your questions for Celia and Beth beforehand (during registration), or ask them live during the webinar.
Spring Plant Sale
Join us for the annual Piedmont Master Gardeners plant sale! Featuring native plants, bulbs and tubers, herbs, ground covers, pollinators, perennials, drought-tolerant plants, houseplants, annuals, veggies, sun and shade plants, deer resistant plants, trees, shrubs, fruit, Green Elephant sale and…
Basil: Beautiful and Aromatic
When I think about summer gardening, sweet basil, Ocimum basilicum, is one of the first plants that comes to mind. From June through September, I keep bundles of fresh basil in containers on my kitchen counter, where its wonderful fragrance fills the air. Handy accessibility is essential, because I use these bright green leaves so often in meal preparation. Without fail, I also grow basil in strategic locations in my outdoor edible garden, within easy reach of my fingertips.
As a culinary and medicinal herb, basil has been cultivated for more than 5,000 years. This attractive plant, native to Asia and Africa, is a member of the Lamiaceae (mint) family. Its shiny, paired (opposite), oval-shaped leaves with pointed ends branch directly from a central stem. Most basil varieties have small white flowers, but a few can boast lovely purple blossoms. A thick taproot beneath the soil surface holds the plant upright. Regarding basil’s piquant taste and savory aroma, several natural compounds (oils) with names you probably never heard of – estragole, linalool, and eugenol – are the culprits.
White flowers on Genevese basil. Photo: Pixabay
Types of Basil
There are ~35 different types of basil and more than 160 cultivars. This article focuses on those that are well-known and widely-used in our region. If you want to explore new basil varieties, you can find most of these online or in mail-order seed catalogs, such as Park Seed, Burpee, or Johnny’s Selected Seeds.
Genovese: This traditional Italian basil is frequently used in tomato sauces or added to fresh salads. Its distinctive anise flavor and sweet clove-like smell make this basil a popular choice for many recipes. You may also want to try Red Genovese, which has dark purple leaves and rich taste.
Deep purple leaves on Red Genovese basil. Photo: Pixabay
Napoletano: This basil is a bit spicy, which makes it ideal for flavorful pesto, especially because it produces lots of large leaves for harvesting.
Siam Queen: This is one of several Thai basils with intense licorice flavor and notable aroma. Due to the purple stems and unique shape (like a sphere), this variety is often used as an ornamental plant.
Cinnamon: This Thai basil offers a delightful cinnamon taste, and it’s scrumptious when added to baked goods. This variety, sometimes called Mexican spice basil, has deep purple stems with narrow, dark green leaves.
Lemon or Mrs. Burns Lemon Basil: Noted for its tangy lemon flavor, this variety is a great addition to soups, stews, and curry dishes. It’s often used in Indonesian cooking.
Greek Dwarf: This compact plant with tiny leaves grows in a globe-like shape. It’s an excellent choice for container gardens, and the strong, spicy flavor makes it a perfect choice for sauces, soups, and salad dressings.
Dark Opal: This beautiful basil with showy purple leaves and deep pink flowers is favored for colorful pots and pollinator gardens. It has an unusual anise taste with a slight hint of ginger.
Cultivation
Basil seedlings in the garden. Photo: Pixabay
I think of basil as a “user-friendly” plant. Basil is fairly easy to cultivate (seeds or young plants), and given appropriate conditions, it will be consistently productive during the summer growing season. Basil is a warm-season crop, so wait until temperatures are consistently above 70° F during the day and above 50° F at night to consider outdoor planting. Basil is highly sensitive to frost, which means you should hold off on planting this in the garden until two weeks after the last frost date (between April 15-25) for our hardiness zone (7a for Albemarle County). Since you can never be certain when our area is finally beyond chilly nights, I recommend waiting until the second or third week of May to sow seeds or plant basil outdoors.
Pollinators love sweet basil flowers. Photo: Pixabay
To thrive, this delightful culinary herb needs fertile, well-drained soil with a pH of 6-7. Be sure that your basil plants get plenty of sunlight (6-8 hours), but if your site allows for a couple hours of late afternoon shade, basil will appreciate that. Rather than planting basil in straight rows, try “interplanting,” or placing individual basil plants in-between other crops in your edible garden. Why? Due to their chemical composition, basil plants may repel some insect pests that tend to wreak havoc in outside beds, such as aphids, mites, and tomato hornworms. I tried this last year, strategically planting selected basil varieties near different kinds of tomato plants in my own garden. Results indicated that this method works. I didn’t find a single hornworm in 2021, and after one minor aphid attack, I was able to get rid of the offenders and keep them away for the rest of the growing season. To learn more, read “Plant Partnerships in Your Garden” (Garden Shed, May 2021).
Another benefit? Deer don’t like the strong smell of basil. Try planting it near the edges and corners of your garden to discourage deer browsing.
Potential Problems
Like most outdoor plants, basil is subject to certain infectious diseases. Downy mildew, which lives in soil and plant debris, is one of the most destructive. Be on the lookout for yellowing leaves with fuzzy undersides. Humid conditions encourage the reproductive sporangia to spread, so make sure basil plants have sufficient air circulation. Fusarium wilt is a fungal, soil-borne pathogen that causes stunted growth. Watch for sudden leaf drop and brown streaks on basil stems. Bacterial leaf spot is another disease that affects basil. It spreads in the soil and leads to angular spots, brown or black, on leaves. Careful observation and good sanitation practices in the edible garden, such as regular weeding, removing unhealthy stems and leaves, and cleaning up dead plant material, are the best preventive measures you can take to avoid these problems.
Harvesting Basil
Once well-established, basil plants are quite beautiful. Remember to “pinch” stem tips regularly to encourage bushier growth. Use clean, sharp scissors and cut just above a pair of leaves. Pinch away freely, as this herb will respond with increased, vigorous growth. In the summer, I make it part of my daily morning routine to step into the garden and pinch basil, enjoying the wonderful aroma as I go. Plus, you will enjoy more flavorful basil if you pinch stems early in the day, just after the dew dries. For best taste, be sure to pinch stems before the flowers appear.
Pinch basil leaves frequently. Photo: Pixabay
Learn more about growing, harvesting, and preserving herbs in the Garden Shed in Pat Chadwick’s article (March 2021) and VCE publication 426-420 titled “Herb Culture and Use.”
Storage and Use
For use in food preparation, fresh basil is best. You can dry basil leaves (keep them whole), but the flavor of dried basil is much less pungent. To dry whole leaves, place them on a drying screen and later put them into an air-tight container for storage. Avoid crushing the dried leaves until just before use. Alternatively, you can put fresh basil leaves into ice cube trays, add a little water, and freeze them. Once frozen, transfer the basil to sealed containers for freezer storage. Use “basil ice cubes” when making soups, sauces, and stews.
Sweet basil in a pot. Photo: Pixabay
To jazz up your daily food intake, consider adding this culinary herb to various dishes. You can explore many mouth-watering recipes available through the Herb Society of America. Here’s a glimpse of what they offer: basil oregano pesto, basil nasturtium salad, basil-blueberry muffins, lemon basil snap beans, and basil cinnamon ice cream. I’m eager to jump-start the growing season by expanding my repertoire of recipes. Hope you are, too!
References in Print
“Flavorful Basils” by Sue Guetz. The American Gardener, July/August 2021 issue.
Online Resources
“Basil.” Cornell University, Botanic Gardens, reference tool with links.
“Basil.” Herb society of America, informative articles about different types of basil.
“Basil, A Great Culinary Herb.” NC State Cooperative Extension, article by Minda Daughtry.
“Basil, A Summer Favorite.” Penn State Extension, illustrated article about basil.
“Basil Diseases: Various Pests.” Cornell U Plant Disease Diagnostic Clinic, descriptive article.
“Basil Downy Mildew.” Cornell U Department of Agriculture and Life Sciences, informative article with photos.
“Herb Culture and Use.” Virginia Cooperative Extension Publication 426-420 by Shawn Appling and Joyce Latimer.
“How to Grow, Harvest, and Preserve Culinary Herbs.” Piedmont Master Gardeners, Garden Shed article, March 2021.
“Ocimum basilicum.” Missouri Botanical Garden, article on basil.
“Ocimum basilicum.” NC State Extension Plant Toolbox, article and video about basil.
“Plant Partnerships in Your Garden.” Garden Shed article about beneficial plant partners.
“Virginia’s Home Garden Vegetable Planting Guide.” Virginia Cooperative Extension, hardiness zone map and details.
Coming to a Garden Center Near You
If you’ve ever wandered the aisles of a garden center wishing it were easier to find the natives you’re eager to plant, you’re in for a delightful surprise. On your next plant-shopping trip, you’ll be greeted by bright red “Virginia Native” labels on every plant that is native to our ecoregion. Those bright labels are part of the Plant Northern Piedmont Natives Campaign (“PNPN”), which is in turn part of a statewide effort — the Plant Virginia Natives Campaign — to encourage more extensive use of native plants in both public and private landscapes. To learn more about the statewide campaign and to access lots of excellent resources, check out Plant Virginia Natives.
Look for these red stickers when you shop for plants. Photo: Cathy Caldwell
Volunteers with the Piedmont Master Gardeners have been working on the PNPN campaign along with their partners, the Virginia Native Plant Society, the Piedmont Environmental Council, and the Virginia Department of Wildlife Resources. A key first step was enlisting local garden centers and nurseries, an effort which was remarkably successful.
Volunteers deliver signs to local garden centers. Photo courtesy of Bernice Thieblot.
Next, volunteers went to work on developing a list of plants that are locally native and suitable for local growing conditions. A starting point was the plants identified by the Digital Atlas of Virginia Flora as native to Charlottesville and Albemarle County, and to the counties of Buckingham, Culpeper, Fauquier, Fluvanna, Greene, Louisa, Madison, Nelson, Orange, and Rappahannock. To those were added certain cultivars of straight species — sometimes called “nativars” — but only after they had been vetted to ensure they are ecologically viable, meaning their leaves and flowers contribute to the food web and do not negatively alter insect behavior. In other words, caterpillars and pollinators will not turn up their noses at these cultivars.
The cultivar-vetting process was guided by recent research, which indicates that a cultivar is ecologically viable so long as it exhibits characteristics similar to the species plant. Thus, cultivars that have significantly changed flower color or morphology are not included, nor are cultivars that change green leaves to red, purple/brown, or blue. A number of the included cultivars were identified by formal scientific studies comparing their environmental services with those of straight species. To learn more about this research, see The Garden Shed article Native Species or Cultivars of Native Plants–Does it Matter?.
The PNPN list now contains over 300 plants. Volunteers with the campaign have been busy placing the red “Virginia Native” stickers at local garden centers as spring shipments arrive. In addition, they have developed and delivered educational materials to the participating garden centers.
Volunteers just recently completed three new brochures to guide gardeners in choosing the right native plant for their particular situation. You’ll find them at participating garden centers and nurseries. With this information in hand, we gardeners will not only be able to find local natives, we’ll be able to make informed decisions about which ones to purchase for our gardens.
SOURCES:
Plant Virginia Natives Campaign Website