The Garden Shed

A Community Newsletter published by the Piedmont Master Gardeners

March 2017-Vol.3 No.3

When to Prune

Sweet Potato Soup

The Ornamental Garden in March

Plumbago — A True Blue Accent in the Sunny Border

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.

The Garden Shed- Who We Are

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

Recipe of the Month

Sweet Potato Soup

By Cate Whittington

Simple Ingredients and Easy Preparation Yield a Tasty, Nutritious Pot of Soup!

Tasks and Tips

The Vegetable Garden in March

By Cleve Campbell

Tasks and Tips

The Ornamental Garden in March

By Pat Chadwick

It's Spring! Time to shed the winter coat and start working in the garden!

In the Ornamental Garden

Plumbago — A True Blue Accent in the Sunny Border

By Pat Chadwick

For a touch of blue in the garden, plumbago may be the plant for you.

Feature

When to Prune

By Cleve Campbell

I remember the joy of......

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Back Issues

The Ornamental Garden in March

March 9, 2017
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Early spring crocuses in bloom

March is that long-awaited month marking the official end to winter and the beginning of the gardening season. What a joy to see the soft green haze of emerging foliage, the swelling buds of flowering ornamental trees and shrubs, and the first blossoms of spring-blooming bulbs as they emerge from the thawing soil. It’s time to shed our winter coats and venture out into the garden.

OUTDOOR GARDENING TASKS IN MARCH

Complete unfinished late winter pruning chores before your plants break dormancy:

Cut back perennials and ornamental grasses that were left standing over the winter. Cut back to within a few inches of the ground so that you don’t damage the plant’s crown.
Prune Group 3 (late summer or autumn-flowering) clematis vines to 12 inches from the ground. Cut each vine back to a strong bud. Although clematis may not need to be pruned every year, pruning does stimulate new growth and more prolific flowering, plus it takes the weight off the vines. For more detailed information on pruning clematis vines, see Clematis — Queen of the Vines in the May 2016 issue of The Garden Shed.
Rosebush Pruning Guidelines

Prune roses early in the month to promote vigorous new growth, improve air circulation and allow light into the center of the plant. Remove any broken canes, dead tips, and older canes. TIP: Older canes normally appear drier, or shriveled, and darker than newer canes. As you prune, make 45-degree cuts one-quarter inch above healthy buds, angled away from the center of the plant. Some of the newer repeat-blooming shrub-type roses may only require a light shaping, if that much. The American Rose Society’s website has several useful articles on pruning roses, including Ten Principles of Rose Pruning and All About Pruning. The latter of these two articles contains many useful photos, clearly illustrating how to make pruning cuts.

Apply a slow-release granular fertilizer or organic product to established trees and shrubs that showed signs of nutrient deficiencies last year. While overall poor plant growth and vigor may be symptomatic of nutrient deficiencies, some specific symptoms include pale or chlorotic leaf color, smaller than normal leaf size, and premature leaf drop. If you’re not sure what’s going on with your plants, don’t fertilize until after you’ve had a soil test done to identify specific nutrient issues. See Virginia Cooperative Extension (VCE) Publication 452-129 for information on Soil Sampling for the Home Gardener. If fertilization is indicated, it is best done about four to six weeks before the plant starts to show new growth. Thoroughly water in the fertilizer or organic matter. For more information on fertilizing woody plants, see Virginia Cooperative Extension Publication 430-018, Fertilizing Landscape Trees and Shrubs.

Apply a dormant horticultural oil to deciduous trees or shrubs if you observe problems with scale or other overwintering insect species. Adult scales have waxy coverings that protect them from insecticides. Control measures must therefore be applied before leaves appear in spring, while the insect is in the immature or crawler stage. Outdoor temperatures need to be above 40°F with no chance of rain or freezing weather within the following 24 hours. Also, be aware that dormant oil is toxic to some plants, such as beech, red maple, and smokebush. Therefore, it is important to read and follow instructions carefully before applying any pest controls. If you’re uncertain about the best means of eradicating insect pests, contact the local VCE office for advice at (434) 872-4583 or the Help Desk at albemarlevcehelpdesk@vt.edu.

INDOOR GARDENING PROJECTS IN MARCH

March can sometimes be cold and dreary, making it either impossible or impractical to do much garden work outside. If that’s the case, fear not! There are still lots of projects you can undertake indoors while you’re waiting for warmer weather.

Pot up tender or summer-blooming bulbs now so that they may be transplanted outdoors in May. Caladium, elephant ear (Colocasia), Crocosmia, gladiolus, and tuberous begonias are just a few of the bulbs that may be started indoors this month. Plant the bulb or tuber in a moist, soilless potting mix and keep it warm until new plant growth appears. Then, move the potted plants to a sunny window or place under grow lights. Keep the growing medium moist but not soggy. Once all danger of frost has passed later this spring, gradually move the plants outside.
Marigold Seedlings

Get a head start on warm-season annuals. Many annuals may be started indoors about 6 to 8 weeks before the last spring frost date (May 15 in this area of Virginia). Check the guidance provided on the seed package to get a better idea of how long the plants need to germinate and mature sufficiently before planting outdoors. Plant the seeds in a moist soilless potting mix. Once the seedlings develop two sets of true leaves, plant them in slightly larger containers. Gradually introduce the seedlings to outdoor conditions before planting them after the last frost date in May.
Test old flower seeds to see if they’re still viable. It’s not easy to find accurate information on the longevity of flower seeds. Several factors have to be taken into consideration: the plant species, the condition of the seeds when they were collected, and how well they were stored. The seeds of some plant species, such as candytuft, columbine, salvia, strawflower, and vinca, tend to be short lived, viable for perhaps only one or two years. Others, such as calendula, cosmos, marigold, nasturtium, nigella, and zinnia, may be viable for several years if stored properly. When in doubt, here’s how to do a seed viability test:
Seed Viability Test
- Space out at least 10 or more seeds on the top half of a damp (but not soggy) paper towel.
- Fold the bottom half of the paper towel up over the seeds. Fold the paper towel again, or roll it up and insert it into a plastic baggie.
- If you’re testing more than one plant species, write the name of the seeds on the baggie.
- Place the baggie in a warm spot (about 70 to 75 degrees) but don’t put it in sunlight. The seeds need warmth, but not light, to germinate. Your kitchen is probably a good spot.
- Check the paper towel daily to make sure it is still moist. Re-dampen as necessary.

After about a week, check the seeds to see how many sprouted. Most seeds will have sprouted within 10 days. If more than 50% of the seeds germinated, then you know they are still usable. However, you might want to plant them a little thicker than normal to make up for the loss of vigor. If the germination rate is low (less than 50%), either plant plenty of seeds to make up for the low germination rate or toss the remaining seeds and buy fresh ones.

TIPS FOR INVOLVING CHILDREN IN GARDENING

Gardening is one of the few multi-generational activities that can be enjoyed on so many different levels. If you have a small child or grandchild, instill in them a love of nature by engaging them in planting and caring for an ornamental garden. Lest they view this activity as “work,” don’t lose hope. Appeal, instead, to their senses – specifically to their sense of wonder. For example, select flower species for your garden that not only offer visual appeal but also appeal to other senses as well:

Smell:
Fragrant Sweetpea Blossoms

Unless your child suffers from seasonal allergies, plant fragrant ornamentals such as roses, lilacs, hyacinths, lavender, sweet peas, chocolate cosmos, and peonies. These are just a tiny sampling of fragrant plants that appeal to one’s sense of smell. Be sure to warn your child to look for bees or other insects first before they attempt to smell a flower.
Taste: Let your little one experience the taste of an edible flower such as a nasturtium, violet, rose, or calendula – under adult supervision. Make sure the plant has not been treated with pesticides or other chemicals.
Edible Nasturtium Flowers and Foliage

Also, because some plants are poisonous or might cause an allergic reaction if eaten, train your child not to taste any plant without checking with mom or dad first. If you’re not sure which flowers are edible, check out the North Carolina State University Extension Service publication on Choosing and Using Edible Flowers. It describes many edible flowers and includes lots of photos.
Touch:
Fuzzy Lambs Ear Foliage (Stachys)

Lamb’s ear (Stachys byzantina) has soft, fuzzy foliage that kids love to touch. Chenille plant (Acalypha hispida) is another plant with soft, furry flowers that a child might want to stroke. Some ornamental grasses, such as pink muhly grass (Muhlenbergia) or Lagurus ovatus ‘Bunny Tails’, have soft, fluffy flowers that your child will surely want to touch.

Noisy Baptisia Seedpods
Sound: Teach your child to listen to the rustling sounds that quaking grass and other ornamental grass seed heads make in the breeze. Show them how to shake the ripe seed pods of plants such as false indigo (Baptisia) or love-in-a-mist (Nigella damascena) so that they make rattling noises.

In addition to appealing to the senses, gardening provides ample opportunities for many memorable teachable moments. For example:

Your child will be amazed to learn that plants have a built-in ability to tell time. Show them plants that open at sunup and close at dusk. Examples include morning glories (Ipomoea), sun drops (Oenothera fructicosa), moss rose (Portulaca) and California poppies (Eschscholzia californica). Delight them with fragrant moonflowers (Ipomoea alba), evening primrose (Oenothera biennis), and flowering tobacco (Nicotiana), which open at dusk and close at sunup. And then there are four o’clocks (Mirabilis), which open at approximately the same time each afternoon and close by sunup the next day.
Planting a variety of colorful annuals and perennials is a great way to teach a young child the names of colors. Zinnias are perhaps the best example of a common but charming flower that is available in all the colors of the rainbow – red, yellow, white, purple, and dozens of shades in between, including chartreuse. Show an older child how to use a color wheel in the garden as a way to learn the differences between primary, secondary, and tertiary colors.
Amaze your child with the variations in plant size. On one end of the spectrum, all children and most adults are amazed by the sheer height of a sunflower (Helianthus). This fun plant germinates fast and, depending on the selection, can stretch up to 10 feet tall. Teach your child about heliotropism as they observe the super large flowers follow the sun. Hollyhocks are another tall plant that delight children with their height and bright cheerful blossoms. Elephant ears are yet a third large plant that amaze and delight with their enormous leaves. Conversely, help your child plant a fairy garden. Fill it with miniature ferns, ivy, moss, low-growing sedum, hens and chicks, or other small plants. Let it appeal to your child’s imagination and sense of whimsy.
Use plants as a way to open your child’s eyes to the wonders of nature and the interconnectedness between plants and animals. Plant colorful, nectar-rich annuals and perennials that attract butterflies, bees, and other insects. Plant milkweed (Asclepias), for example, and show your child how to identify the eggs, larva, and pupa stages of the butterflies that rely on the plant for sustenance.
Show your child how to have fun in the garden. Kids love to pinch snapdragon blossoms so that the “dragon’s mouth” snaps open and shut. To encourage giggles, show them how to touch a ripe “touch-me-not” (Impatiens balsamina) seedpod and watch it shoot out seeds as if they were spring loaded. Even the name of the plant sounds like fun. And then there’s the money plant (Lunaria), also called silver dollar plant. The name may not inspire giggles, but it will be amazing to see how the pretty little lavender blossoms give way to large, silvery, translucent seed pods.

WAYS TO ATTRACT HUMMINGBIRDS TO THE GARDEN

Ruby-Throated Hummingbirds at Feeder

As you plan this year’s ornamental garden, consider adding plants that will attract hummingbirds. According to the Audubon Society (audubon.org/plantsforbirds), hummingbirds must eat every 10 to 15 minutes in order to sustain their super-fast metabolisms. This means visiting anywhere from 1,000 to 2,000 flowers per day. While hummingbirds are particularly attracted to red or orange trumpet-shaped blossoms, they will come to any plant that has a good supply of nectar.

To create a hummingbird-friendly habitat, consider ways to address its basic needs:

Nectar-rich plant species: Nectar-rich plants that attract hummingbirds include: Bee balm (Monarda), cigar plant (Cuphea), salvia species, Penstemon, Agastache, native honeysuckle (Lonicera sempervirens), cardinal flower (Lobelia cardinalis), gayfeather (Liatris), columbine (Aquilegia canadensis), foxglove (Digitalis purpurea), scarlet runner bean (phaseola coccineus), passionflower (passiflora incarnata), hyacinth bean (Dolichos lablab), Kniphofia, Weigela, and Pentas.
Nectar Feeders: Feeders are particularly critical during the spring and fall migration when nectar-rich flowers are not plentiful. Because hummingbirds are territorial, it’s wise to have feeders in place before they return to this area in early April. Once a hummingbird decides it likes your feeder, it will tend to stick around for the rest of the season. Also, if you hang more than one feeder, place them far enough apart so that the hummingbirds can’t see one another. That will keep the peace in your yard. Fill the feeders with sugar water made from a mixture of one part plain sugar to four parts water that has been boiled for 1 to 2 minutes and cooled. Change the sugar water in the feeder about twice a week.
Protein sources: In addition to nectar, hummingbirds require protein in their diet. They eat protein-rich pollen, small insects, and spiders. Baby hummingbirds that are still in the nest are fed insects almost exclusively. So, include pesticide-free plants that are pollinated by insects in your garden. TIP: Place overripe fruit or banana peels near the hummingbird feeder to attract fruit flies and watch the hummingbirds snatch them from the air.
Perches: Hummingbirds need safe places to rest, preferably out of the reach of cats and birds of prey. They like to be able to survey their territory and this means maintaining some shrubs or small deciduous trees in which they can rest without being seen.
Nests: Small trees and shrubs also appeal to hummingbirds for nesting purposes. They tend to build their tiny nests on the small bare limbs of trees and shrubs or on other small horizontal surfaces. Also, don’t be so quick to tear down spider webs when you see them. Hummingbirds often use the webs for building their nests.
Water: Hummingbirds like to bathe often, so provide a source of water (a tiny amount will do) or even a fine mist for them.

Once you’ve provided the right habitat for hummingbirds, they’ll reward you endlessly with their amazing aeronautical feats and entertaining antics.

Plumbago — A True Blue Accent in the Sunny Border

March 9, 2017
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As their name suggests, groundcovers are plants that grow thick and spread to cover the ground. However, the very characteristics that we look for in a groundcover – matting, spreading, or vining — can also make them disagreeable to live with in the ornamental garden. Plumbago (Ceratostigma plumbaginoides) is a spreading plant that embodies many of the best characteristics of a groundcover without resorting to thuggish tendencies. This plant is relatively underused in the Mid-Atlantic states, perhaps because it is deciduous. Gardeners may prefer more popular evergreen groundcovers, such as vinca, pachysandra, and English ivy. Or, perhaps its many common names (leadwort, perennial leadwort, plumbago, hardy plumbago, or dwarf plumbago) confuse the average home gardener. More often than not, it is identified simply as either plumbago or leadwort. As for the origin of the name, it comes from the Latin plumbum, which means lead. The plant was thought to be a cure for lead poisoning, according to the writings of Pliny the Elder in the first century AD. While it may not cure lead poisoning, it does make a very effective groundcover.

DESCRIPTION

Hailing from western China, plumbago is a deciduous, flowering herbaceous perennial with a low-growing, mat-forming habit. It spreads about 12” to 18” wide and grows 6” to 10” tall. In his book Herbaceous Perennial Plants, 3^rd Edition, world renowned horticulturist Dr. Allan Armitage describes it as “a terrific species, looking equally as good in Athens, Georgia and Niagara, Ontario.” As further evidence of its value in the landscape, plumbago was recognized as a Georgia Gold Medal Winner for perennials in 2006.

Plumbago foliage is late to appear in spring. When it does sprout, the new 1-1/2” long leaves have a reddish tint that gives way to a medium-textured, glossy, bright green color in summer. One of the benefits of this plant is that the foliage looks fresh all summer long, regardless of the heat and humidity. Then, as temperatures begin to cool, the leaves turn a deep burnished shade of red in autumn.

Summer Plumbago Foliage
Photo Source: Lewis Ginter Botanical Garden

Fall Plumbago Foliage

All too often, plants labeled as blue-flowering turn out to be some shade of lavender blue or even purple. Finding a plant that blooms a clear, unmistakable blue can be a challenge. Plumbago meets that challenge. Its dainty ½ to ¾-inch flowers are an electrifying gentian blue, with a shape and color faintly reminiscent of woodland phlox or vinca. The flowers generally cluster at the ends of slender, erect stems and last from summer, when many other perennials are finished blooming for the season, well into fall. Deep reddish calyces contrast with the intense blue flowers and add additional color in autumn.

Blue Plumbago Flowers with Red calyces

Plumbago spreads by rhizomes, but it is not invasive. It’s a moderate spreader in good garden soils. But, like all groundcovers, it does spread and should be watched to make sure it doesn’t venture too far. It is probably best used in a spot where it either has ample room to spread over time or where it can be contained. If it does grow beyond its allotted space in the landscape, it’s easy to spade up, particularly if the soil is moist.

CULTURAL REQUIREMENTS

Plumbago prefers average to evenly moist, rich soil. Once it is established, it can tolerate dry soil and does not require any supplemental water beyond normal rainfall. It will not tolerate standing water. It is not fussy about soil type or pH and will thrive in poor soils and difficult sites.

Hardy in USDA zones 5 to 9, plumbago does best in full sun. It does tolerate light shade but tends not to bloom as well in shade as it does in full sun.

Plumbago is a tough, low maintenance plant that requires no shearing or pruning. The flowers are self-cleaning, which means no deadheading is required. The foliage drops off after the first frost and the stems may be left in place over winter. The new foliage will cover the old stems. However, if you prefer a tidier garden, there’s no problem with cutting the old stems back, either in fall or late winter. Because new foliage is late to emerge in spring, some gardeners prefer to leave the old stems in place to mark the spot until new growth appears.

OTHER RELATED PLUMBAGO SPECIES

Don’t confuse the groundcover form of plumbago (C. plumbaginoides) with the shrub form (C. willmottianum or Chinese plumbago), which grows 2 to 3 feet tall and is hardy in zones 7 to 9. Another related shrub form of plumbago (C. griffithii, or Burmese plumbago) is smaller than C. willmottianum, has deep blue flowers, and is hardy in zones 6 to 8.

Also, do not confuse C. plumbaginoides with Plumbago aurticulata, a shrub that is native to South Africa. Commonly referred to as cape plumbago or cape leadwort, it is completely different from the Ceratostigma species. Plumbago aurticulata has lighter blue flowers and is only hardy to zone 8. Often found in garden centers in the mid-Atlantic, it must be treated in this area as an annual or grown in a container and overwintered indoors.

PLUMBAGO PROPAGATION

Propagate plumbago by dividing it or taking stem cuttings. Divide in spring before new growth appears. Space the transplants about a foot apart. To promote rapid filling in between transplants, lightly apply a slow-release 12-6-6 fertilizer in the spring and again in the early summer. To propagate using stem cuttings, take 3” to 4” long semi-ripe cuttings during the summer.

PESTS AND DISEASES

Plumbago has no serious disease or insect problems. Despite its attractive green foliage, deer and rabbits don’t eat it, which is huge plus in this area.

RECOMMENDED USE IN THE LANDSCAPE

Groundcovers are used primarily to “knit” the landscape together. With this goal in mind, use plumbago as:

An edging in the sunny border, spanning the space between ornamental plantings and lawn.
A mass planting, serving either as a groundcover or under other plants as a “skirt.”
A graceful filler between stones in rock or alpine gardens.
An alternative (albeit deciduous) to vinca minor and English ivy, both of which are considered invasive.
An alternative to wood mulch to suppress weeds, shade the soil surface, and conserve water.
A camouflage to cover dying bulb foliage in spring. Plumbago foliage emerges in late spring as bulb foliage is dying back.
A means of controlling erosion on slopes or in rocky areas where not much else will grow.
A component of a container garden that will gently drape over the side of the container.
A gentle way to soften the edges of a stone wall. While the plant tends to be upright, the foliage does gently cascade over at the edge of the mass.

Plumbago offers a long bloom time and true blue flowers, which are not commonly found in the landscape. Its colorful fall foliage, drought tolerance, deer resistance and lack of pest and disease problems make it a desirable plant to add to the landscape. If, however, you are a native purist, keep in mind that this plant is not native. It does attract bees and butterflies but not to the extent some of our native plants do.

For more information on groundcovers suggested for Virginia landscapes, see Virginia Cooperative Extension Publication 426-609, “Selecting Landscape Plants: Groundcovers.”

RESOURCES

Herbaceous Perennial Plants, A Treatise on their Identification, Culture and Garden Attributes, Third Edition (Armitage, Allan M., 2008)

Latin for Gardeners (Harrison, Lorraine, 2012)

Perennials, The Gardener’s Reference (Carter, Susan; Becker, Carrie; and Lilly, Bob, 2007)

The Well-Tended Perennial Garden, Planting and Pruning Techniques (DiSabato-Aust, Tracy, 2006)

Chicago Botanic Garden Plant Information chicagobotanic.org/plantcollections#plantfinder

Clemson Cooperative Extension Publication HGIC 1180, Perennial Leadwort

Georgia Gold Medal Plant Summary 1994 – 2010, Gold Medal Plant Summary

“Selecting Landscape Plants: Groundcovers,” Virginia Cooperative Extension Publication 426-609

Sweet Potato Soup

March 8, 2017
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In November, I included a recipe in The Garden Shed for Sweet Potatoes in Orange Cups. Now, just four months later, I decided to return to this highly touted super food. Not only does this tuberous plant pack a nutritional punch, but also it is readily available all year long. So, while we seasonal cooks patiently await those first spring peas or early radishes to appear in the garden, let’s enjoy a warming bowl of simple soup as chilly days linger into spring.

The following recipe is super easy. It is adapted from Melissa and Dallas Hartwig’s popular book, The Whole 30. Their 30-Day Guide to Total Health and Food Freedom contains recipes designed with even the most inexperienced cook in mind—simple ingredients, easy preparation, and tasty results. As always, feel free to add onion and additional spices to make it your own savory soup. Try adding orange juice, a chopped apple, and even some pre-cooked meat for a heartier meal.

Ingredients (Serves 2-4)

2 Tablespoons cooking oil

2 sweet potatoes, peeled and large-diced

½ teaspoon ground ginger (or 2 Tablespoons minced fresh ginger)

1 pinch ground cinnamon; extra for garnish

1 cup full-fat coconut milk

½ teaspoon salt

¼ teaspoon black pepper

Directions

In a Dutch oven or large pot, heat the cooking oil over medium heat, swirling to coat the bottom of the pot. When the oil is hot, add the sweet potatoes, ginger, and cinnamon, and stir for 15 seconds. Add 3 cups of water and the coconut milk and bring to a boil. Simmer until the sweet potatoes are soft, about 20 minutes. Remove the pot from the heat and puree the mixture with an immersion blender or food processor. Return the soup to the pot and cook over medium low heat to the desired thickness. Season to taste with salt and pepper, garnish with extra cinnamon, and serve.

Resources:

The Whole 30 (Hartwig, Melissa and Dallas, 2015)

The Vegetable Garden in March

March 8, 2017
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1 Comment

Wow, it’s March, and the days are growing longer, so we can be blessed and teased with mild warm days, cold snowy days, rain and windy days. March is the month of many seasons. Regardless of the unpredictable weather, March is the start of the spring gardening season, a time to complete those winter tasks we dare not carry over into the spring rush season, when there are so many tasks and so little time. Finishing fall and winter garden tasks, purchasing seeds, and starting the 2017 vegetable garden are the March tasks that compete for the gardener’s attention. In addition to all those tasks, the gardener is often overcome with a severe case of spring fever brought on by warmer weather and compounded by a visit to a local gardening center or nursery were we are confronted with racks of irresistible seed packets on display! Sometimes it’s difficult to remember that it’s not yet spring. However, for that gardener with a bad case of spring fever and an urge to dig in the dirt, there are cool weather crops that may be planted in March.

The following list of cool weather crops was compiled from the VCE publication “Vegetable Planting Guide and Recommended Planting Dates” and indicates which vegetables may be planted in our area after the middle of March:

Asparagus (crowns)

Collards

Leeks

Mustard

Kale

Onion (sets)

Peas

Spinach

Radish

Turnips

Potatoes

In a hurry to get those tomato and pepper seeds started indoors? The general rule of thumb is to start tomato and pepper seeds indoors about 6-8 weeks before the final frost, which in our area is around May 15th (VCE Publication 426-331), and that means we need to hold off starting those seeds until around the end of March. Peppers, however, need about an additional 2-3 weeks head start and can be started earlier.

It’s not too late for a soil test! It never fails — whenever I contact the local extension office about a problem in the garden or orchard, their first response is “when was the last time you did a soil test and what were the results?” So now before I ask, I test! A soil test is a valuable tool for not only identifying problems but preventing problems as well. A soil test is a tool that allows you to keep your soil at optimum fertility levels and pH levels. To keep your garden fine-tuned, you need to perform a soil test every 2-3 years. A soil sampling kit complete with instructions is available for free at your local Virginia Cooperative Extension Office. For additional information on soil testing check out VCE PUBLICATION 452-129.

Lettuce is very sensitive to low pH levels (acid), so lime should be applied to your lettuce bed if the pH is below 6.0. YES, you will need a soil test to determine the pH level and the need for lime!

Don’t throw away that leaky old garden hose! You can use it to protect yourself and the blades of your pruning saw during storage. Make a cover for the saw blade with a piece of old gardening hose. Cut a section of the gardening hose to the same length as the blade. Cut the hose lengthwise on one side and place it over the saw blade.

If your garden soil crusts after a rain, this may result in poor germination, because young seedings are too fragile to break though the crust. This problem may be caused by over-tilling the soil. Cover the seeds with ¼ inch of compost or fine mulch matter, which will keep the soil moist and help prevent crusting.

If you are planning a backyard orchard, start by mapping out the site, giving particular attention to air and water drainage. Remember, just like water, cold air flows down hill. Avoid frost pockets — areas where cold air gathers — or you may be disappointed year after year when flower buds freeze and drop, resulting in little or no fruit.

Often seed catalogs and seed packets indicate a planting time, sometimes using the phrase, “as soon as the soil can be worked.” One simple test to determine if the soil can be worked is to squeeze a hand-full of soil into a ball. If the soil holds together in a wet or sticky ball, it’s too wet to work. One of my favorite tools to take the guesswork out of knowing when to plant is a soil thermometer. Soil temperature is the best indicator that the time is right for planting. As a general rule, cool season crops — collards, leeks, peas, radish, and spinach — can be planted when the soil reaches a temperature of 45-50ºF, while warm season crops — cucumbers, squash, corn, beans and melons — require a soil temperature above 65º F.

March is a good time to begin a compost pile if you have not done so already. Most garden centers or nurseries sell composting bins. For help in planning your compost pile see our 2016 February feature article on compost in The Garden Shed, or view the VCE Publication 442-005, “Composting Your Organic Kitchen Waste with Worms.”

Not sure what vegetables or specific varieties of vegetables to plant? Check out VCE Publication No. 246-480 “Vegetables Recommended for Virginia,” which provides a comprehensive listing of recommended varieties.

Spring fertilization of fruit trees should occur about 3-4 weeks before active growth begins. Scatter fertilizer evenly under the tree, starting about 2 feet from the trunk and extending just beyond the drip line or end of the furthest branches. A soil test should be performed prior to applying fertilizer. For additional information of fruit trees visit VCE Publication 426-841, “Tree Fruit in the Garden.”

The optimum time to prune fruit trees is just before they bloom. Pruning allows the tree to direct nutrients to branches that will bear high quality fruit. The object is to remove dead, diseased or damaged wood. Also, remove shoots that are growing straight up or straight down as neither provides for good fruit development. Growth crisscrossing the center of tree should be removed as well. A more open tree allows greater light penetration and air circulation, thereby increasing fruit quality and reduced disease and insect pressure. For additional pruning information, visit VCE Publication 422-025, “Physiology of Pruning Fruit Trees.”

Bramble fruits such as raspberries and blackberries may be planted in mid to late March. Plant in moist, well-drained soil containing large amounts of humus or organic matter. For weed control, mulch around newly planted brambles with a hardwood or softwood mulch. For additional information on how to grow bramble fruit, visit VCE Publication 426-840, “Small Fruit in the Home Garden.”

Thanks for stopping by The Garden Shed. We hope to see you again next month.

Resources:

“Vegetable Planting Guide and Recommended Planting Dates.” Va. Coop. Ext. Publication 426-331, http://pubs.ext.vt.edu/426/426-331/426-331.html

“Vegetables Recommended For Virginia,” Va.Coop. Ext. Publication 426-480, https://pubs.ext.vt.edu/426/426-480/426-480.html

“Is it time to plant vegetables? Ask your soil thermometer,”Oregon State University Extension, http://extension.oregonstate.edu/gardening/it-time-plant-vegetables-ask-your-soil-thermometer

When to Prune

February 26, 2017
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7 Comments

I remember the joy of unwrapping my new pruners; I just couldn’t wait to get outside to check out how sharp they were and to attack a few shrubs that were swallowing up the deck. I just had to slow those suckers down before they engulfed the house and started growing though the windows. It was time to declare war on those overgrown bushes. I was jacked; with pruners in hand, I headed out the door, craving some pruning action. Before I could even give the doorknob a half turn, I heard that all-too-familiar voice, “Where are you going with those pruners?” I responded quickly, “I’m just heading out to try out my new pruners.” My response was quickly squashed with a stern frown and voice. “Just because you have sharp pruners doesn’t mean it’s time to prune!” Well, that certainty put a damper on that old garden myth, “You prune when the pruners are sharp.” Now that we’ve got that myth out of the way, let’s take a more scientific look at the when-to-prune question, along with some other pruning basics.

What is Pruning?

Pruning is the selective removal branches while maintaining the plant’s natural form. Pruning is NOT the same as shearing, which is clipping of all new shoots to create an artificial form. Based on aesthetics and science, pruning can also be considered preventive maintenance. Pruning correctly during the formative years may prevent many problems.

Why we prune

Pruning is good for the overall health of a plant. We prune for a number of reasons, including: improving structure, controlling plant size, to define garden space (hedges), to create special effects such as a topiary or espalier, to reveal colorful bark or enhance winter silhouette, to affect flowering and fruiting and for safety — to prevent personal injury or property damage. Pruning improves the health of the plant by removing dead wood and branches that are dying from disease or severe insect infestation, as well as branches that have been broken by animals, storms, or other adverse conditions.

On the left, an unpruned 15-year-old shade tree. On the right, a 15-year-old shade tree that was properly pruned when young. Illustration adapted from “How to Prune Young Trees,” Tree City USA Bulletin No.1, National Arbor Day Foundation.

Now back to my new pruners, and that proverbial question of when is the right time to attack those overgrown bushes swallowing up the deck. After a lot of research I came to the realization that correct pruning depends on two things: what plant is being pruned and why.

When to prune

Pruning requirements for trees and shrubs will not only vary according to to species, but will also depend on the purpose of pruning. If pruning is necessary because branches are dead and the tree or shrub causes a safety hazard, pruning can be performed at any time. However, the overall health of the plant should always be taken into consideration before addressing pruning issues. It is important to know that detrimental diseases can easily be spread if trees and shrubs are pruned at the wrong time of the year. For example, oak trees (Quercus spp.) should only be pruned in the winter months when the trees are dormant to prevent the spread of a common fungal disease called oak wilt.

Each tree or shrub has its special pruning time, depending on the time of year that it produces flowers. Pruning your plant at the proper time is critical for success. If you prune a flowering or fruit tree at the wrong time of the year, you’ll probably miss out on that plant’s blooms or fruit for that season. While it isn’t the end of the world and the plant will recover and flower again the following year, it’s definitely disappointing. The risk of missing out on a season’s worth of flowering is probably the main reason most gardeners fear pruning their shrubs or trees.

To determine when to prune a plant without interrupting its bloom cycle, you need to know your plant. One of the keys to not interfering with the plant’s bloom cycle is to know if the plant flowers on “old wood” or “new wood.” These terms get thrown around a lot, but are often confusing. How old is “old wood”? — 6 months? one year? two years or longer? And what qualifies as “new wood”? Here’s what that means:

Plants flowering on “new wood” do NOT develop flower buds until AFTER growth begins in the spring. Plants that flower on new wood develop the flowering buds in the spring and generally flower later in the season. Some examples of plants that that flower on new wood include roses, butterfly bush, and crape myrtle.

Plants that flower on new wood can be pruned in early spring, just as the new growth begins. This leaves plenty of time for the plant to recover from pruning and still create flower buds for the bloom season. The ideal time to do this is after the buds have emerged on the stems but before they expand. Early spring is the busy pruning season for plants that flower on new wood. In early spring you can see where the healthy new growth is located, and pruning before the buds leaf out means that the plant doesn’t waste energy on buds you’ll just be cutting off anyway.

Plants that flower on old wood form the flower buds for next year’s blooms during the current growing season. Thus, the buds are carried over through winter on last year’s growth —“the old wood.” After these plants bloom, they begin to form the flower buds for the following year. Plants that flower on old wood generally flower early in the growing season. Some examples of shrubs that flower on old wood include fringe tree, forsythia, azaleas, rhododendrons, and lilacs.

Plants that flower on old wood can be pruned immediately after they finish blooming. If you prune before they bloom (late winter to early spring) you’ll remove the flower buds. If you wait too long after they’ve finished blooming, they may not have time to create flower buds for the next year.

Still not sure when to head out to the yard with those sharp pruners? A pruning calendar can be found at the end of this article.

Deciduous Trees

Trees that shed their leaves annually are classified as deciduous. In general, most deciduous trees are pruned when they are dormant, which simply means that period that begins in the fall when the tree loses its leaves and which ends in spring when the buds start to swell. The ideal time to prune deciduous trees is late winter to early spring. At this time, wound healing is rapid. Also, dormant pruning will have less of an effect on the tree’s growth than pruning during other times of the year. Summer pruning tends to suppress the growth of both suckers and foliage. Late summer or early fall pruning causes vigorous regrowth, which in some species may not harden off by winter, leading to possible cold damage. Another advantage of dormant pruning with deciduous trees is that with the leaves gone it is easier to see the structure of the tree and select branches.

Young tree pruning is often preventive, eliminating structural problems. And remember: whenever unexpected damage from vandalism or bad weather occurs, prune immediately, no matter what the season.

Evergreen trees

Evergreen trees have their leaves year round and include most conifers such as pine and cedar, and some broad-leaved trees such as the holly. Evergreen trees in general require less pruning than deciduous trees. Certain conifers — spruces, firs, and white pines — have whorled branches that form a circular pattern around the growth tip and should not be pruned into the interactive center (where no needles or leaves are attached) because new branches won’t form to conceal the stubs.

Most evergreen pruning is done for corrective reasons, so seasonal timing is usually not as important as it is for deciduous species. Pruning doing dormancy is the most common practice and will result in a vigorous burst of spring growth. Pines and other whorl-branched conifers become denser if new growing tips (candles) are pinched in half as they expand in the spring. Whenever unexpected damage from vandalism or bad weather occurs, prune immediately.

When NOT to Prune

Pruning plants does a number of things to their growth systems. Pruning can stimulate new growth, and new growth is tender. If a cold snap hits, which can happen unexpectedly and fast anytime in fall, any tender new shoots can be damaged, weakening your plant. Fall pruning is not recomended for another reason, too: because decay fungi spread their spores profusely in the fall, and wounds are slower to heal on fall cuts. Fall is a great time in the garden with the changing seasons. But for most plants, it’s best to to leave the pruners, saws, loppers, and clippers in the storage until late winter. But as I mentioned earlier, dead, broken or hazardous limbs can be removed any time of the year.

Pruning is the removal of selected living or dead parts of a plant to maintain appearance, health, and to regulate growth. It is used to increase flowering, rejuvenate, shape and improve structural strength of shrubs. One of the keys to successful pruning is timing. Knowing your plant and knowing the response you’re trying to elicit from your plant are critical factors in determining when to prune.

Thanks for stopping by The Garden Shed. We look forward to your visit next month.

PRUNING CALDENARS

Shrub Pruning Calendar

Legend:

* = Best time to prune
x = Do not prune except to correct damage, hazards, or structural defects
– = Timing is not critical

Note:

Flowers are produced on new (current season) wood
Flowers are produced on wood from past season, pruning while dormant will reduce flowers
Make pruning cuts well below diseased wood (fire blight) – disinfect shears between cuts
Remove old stems to ground yearly to renew
Midseason shear if a formal hedge is desired
Do not cut into old wood that has no leaves or needles
Spring/summer prune to remove azalia caterpillars and galls
Fall/early winter pruning can reduce winter hardiness
Snap candles (new growth) in half when needles are 1/2 to 2/3 their normal mature length

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Note

Abelia

1,4

Almond, Flowering

2,4

Arborvitae

–

Aucuba

Azalea, Deciduous

Azalea, Evergreen

2,7

Barberry, Deciduous

2,4

Barberry, Evergreen

2,4

Bayberry

Beautyberry

1,7

Beautybush (Kolkwitzia)

2,4

Boxwood

Broom (Cytisus)

Butterfly-bush

Camellia, Japanese

Camellia, Sasanqua

Chastetree (Vitex)

Cherrylaurel (Prunus)

Clethra, Summersweet

Cotoneaster, Deciduous

Cotoneaster, Evergreen

Crape Myrtle

–

1,8

Daphne, Fragrant or Winter

Deutzia

2,4

Dogwood, Redtwig

1,4

Eleagnus, Thorny

Euonymus, Deciduous

Euonymus, Evergreen

Forsythia

2,4

Fothergilla

Gardenia

Harry Lauder’s Walking Stick

Hibiscus, Rose of Sharon, Althea

Holly, Deciduous

Holly, Evergreen

2,5

Honeysuckle

2,4,5

Hydrangea, Spring- blooming

Hydrangea, Summer- blooming

Hypericum, St. Johnswort

Indian Hawthorn (Raphiolepis)

Jasmine, Winter

Juniper

–

Kerria (Globeflower)

2,4

Leucothoe

Lilac

2,4

Mahonia, Oregon Grapeholly

2,4

Mockorange

2,4

Mountain-laurel (Kalmia)

Nandina

1,4

Osmanthus, Holly

–

1,5

Pearlbush

Photinia

–

Pieris

Pine, Mugo

Pittosporum

Privet, Deciduous (Ligustrum)

Privet, Evergreen (Ligustrum)

Potentilla

1,4

Pyracantha

2,3

Quince

2,4

Rododendron

Rose

1,3,4

Serviceberry

Smoke Tree

Spirea Spring- blooming

Spirea Summer- blooming

Sumac

1,4

Sweetshrub, Carolina Allspice

Viburnum, Deciduous

2,4

Viburnum, Evergreen

Weigela

2,4

Willow, Pussy

Witchhazel

Yew

–

Calendar Source: A Guide to Successful Pruning, Shrub Pruning Calendar, Virginia Cooperative Extension Publication 430-462, http://pubs.ext.vt.edu/430/430-462/430-462.html

Deciduous Tree Pruning Calendar

Legend:
* = Best time to prune
x = Do not prune except to correct damage, hazards, or structural defects
– = Timing is not critical

Note

1. Avoid pruning in late winter/early spring due to sap flow (more cosmetic than detrimental)

2. Avoid pruning from spring through summer due to insect or disease problems

3. Avoid pruning from October – December due to reduced cold hardiness

4. Avoid pruning after July because flower buds have set

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Note

Ailanthus

–

Alder

–

Ash

–

Bald Cypress

–

Beech

–

Birch

–

1,2

Buckeye

Catalpa

–

Cherry, Flowering

Chestnut, Chinese

–

Crabapple

Crape Myrtle

–

Dogwood

Elm

–

1,2

Fringe Tree

Ginko

–

Goldenraintree

–

Hackberry

–

Hawthorn

Hickory

–

Honeylocust

–

Horsechestnut

Katsura

–

Linden

–

Magnolia

Maple

–

1,2

Mimosa

–

Mountain Ash

–

Mulberry

–

Nyssa, Black Gum

–

Oak

–

Peach, Flowering

Pear, Flowering

Plum, Flowering

and Purple

Poplar

–

Redbud

2,4

Serviceberry

Sophora

–

Sourwood

–

Stewartia

–

Sweetgum

–

Sycamore, Plane

–

Tuliptree

–

Willow

–

Zelkova

–

Calendar Source: A Guide to Successful Pruning Decidous Tree Calendar, Virginia Cooper Extension, Publication 430-460, http://pubs.ext.vt.edu/430/430-460/430-460.html

Evergreen Tree Pruning Calendar

Legend:
* = Best time to prune
x = Do not prune except to correct damage, hazards, or structural defects
– = Timing is not critical

Note

Seldom needs pruning – remove multiple leaders, dead and broken branches
Don’t prune into old wood having no leaves or needles
Prune during growing season to make more compact or dense
To avoid reducing berry production; don’t prune during bloom period
Prune to prevent oak wilt infection
Prune to remove cankers
Flower buds set on previous season (old) wood; winter pruning will reduce spring flowering

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Note

Arborvitae

–

1,2

Atlas Cedar

–

1,2

Deodar Cedar

–

1,2,3

Chamaecyparis

–

1,2

Fir

–

1,2

Hemlock

–

1,2,3

Holly (Evergreen)

–

Juniper/Red Cedar

–

1,2

Leyland Cypress

–

1,2,6

Magnolia, Southern

–

1,7

Oak, Live

–

1,5

Pine

–

1,2,3

Spruce

–

1,3

Calendar Source: “A Guide to Successful Pruning: Evergreen Tree Pruning Calendar,” Virginia Cooperative Extension Publication 430-461 http://pubs.ext.vt.edu/430/430-461/430-461.html

Sources:

“A Guide to Successful Pruning: Pruning Basics and Tools,” Virginia Cooperative Extension Publication 426-455, https://pubs.ext.vt.edu/430/430-455/430-455.html

“A Guide to Successful Pruning: Pruning Shrubs,” Virginia Cooperative Extension Publication 430-459, https://pubs.ext.vt.edu/430/430-459/430-459.html

“A Guide to Successful Pruning: Pruning Deciduous Trees,” Virginia Cooperative Extension Publication 430-456 http://pubs.ext.vt.edu/430/430-456/430-456.html

“A Guide to Successful Pruning: Pruning Evergreen Trees,” Virginia Cooperative Extension Publication 430-457 http://pubs.ext.vt.edu/430/430-457/430-457.html

“When to Prune-Tree Care Tips & Techniques,” The Arbor Day Foundation, https://www.arborday.org/trees/tips/when-to-prune.cfm

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The Garden Shed

March 2017-Vol.3 No.3

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