March is a fantastic month, but it does require some resilience. The sporadic return of wintry weather can be disheartening, even when we know spring is coming. Each warmer day makes it hard for us to resist running straight out to the garden. Tramping around in soggy gardens, however, is not good for the soil. Lime spreaders, wheelbarrows, and other equipment will create compaction. What garden tasks can we do early in the season to celebrate the return of spring?
- Keep weeding winter annual weeds such as chickweed, henbit, purple deadnettle, hairy bittercress, and groundsel. See this link to help with weed identification.
- Redefine bed edges to keep grass from growing into flower beds.
- Seed new lawns and do repairs after the land has drained.
- In late March, cut back perennials, such as coneflower, ageratum, and sedum that were left standing over the winter.
- Cut back ornamental grasses before they start to display new spring growth.
- Spring is the ideal time to divide many perennials. Â For detailed instructions, read this month’s feature article, Guidelines for Dividing Perennials.Â
- Some perennials are late getting started in the spring; mark the spot in some way so you do not inadvertently plant over them. If you didn’t mark them in the fall, or take photos, make a note to mark their locations next year.
- 6-8 weeks before the expected last frost, direct-sow or start indoors annual flowers that thrive in cool temperatures. Examples include: calendula, love-in-a-mist (Nigella damascena), nasturtium, sweet alyssum (Lobularia maritima), and larkspurs. Check the seed package to get a better idea of how long the plants need to germinate and mature sufficiently before planting outdoors. NOTE: In recognition of climate change effects, the Cooperative Extension has redrawn the Hardiness Zone map for Virginia. Albemarle County has been moved from the Mountain to the Piedmont region in zone 7a, effectively changing our expected final frost date from May 10-15 to April 15-25.
- Houseplants will enjoy a spring cleaning. Wash off their leaves, trim off brown edges, remove yellowing leaves, and make sure the soil surface is clear of debris. Liquid fertilizers allow you to more precisely add nutrients. For example, you can increase feeding in the spring when the plant is sending up new growth. Slow-release fertilizers are coated in time-release shells that slowly leach nutrients into the soil. A single application can last between four and ninth months. Always research plant requirements to learn about their specific nutritional needs, and follow fertilizer package directions.
SPRING PRUNING
- Many early spring flowering trees and shrubs begin to break out of dormancy in late February with a beautiful flower display. These early spring bloomers develop blooms on old wood (that is, they formed flower buds during the previous year’s growing season). Pruning them in late winter/early spring removes these flower buds. Wait to prune until AFTER all flowers have faded. Examples include: azalea, daphne, fothergilla, forsythia, spring-blooming hydrangea, lilac, spring-blooming spirea, viburnum, pussy willow (Salix discolor), and spring-blooming witchhazel (Hamamelis vernalis). If you’re looking forward to seeing spring blooms, don’t prune.
- Shrubs that bloom later in the season bloom on new wood, and can be pruned in March. Examples include: beautyberry (Callicarpa americana), butterfly bush (Buddleia), chaste tree (Vitex) summersweet (Clethra), summer-blooming hydrangea, St. Johnswort (Hypericum), and summer-blooming spirea.
- March is a good time to prune evergreen shrubs such as arborvitae, boxwood, cherry laurel, juniper, and yew.
- If you’re wondering about the right time to prune a particular shrub, consult the Shrub Pruning Calendar published by the  Va. Cooperative Extension,  Coop.Ext. Pub.No. 430-462. For detailed instructions on how to prune shrubs, review Va.Coop.Ext. Pub. No. 430-459, and be sure to read A Pruning Primer/Garden Shed 2020.
- Pruning of trees should be completed before growth occurs. Trees should not be pruned while the new leaves are growing. For best tree health, prune only 1/3 of tree at a time. Prune dead, damaged, or diseased branches as well as any cross branches, never the leader branch. For detailed advice, read The How & When of Pruning Trees/Ask a Master Gardener 2020.
- Crepe myrtle is an example of a summer-blooming tree that should be pruned in February/March. For more about this, see How to Prune Crape Myrtles/Garden Shed 2020. Â You may also want to view this short video from LSU AgCenter on how to prune crepe myrtle so that it retains its natural shape, looks beautiful, and remains healthy.
FERTILIZATION
The best way to know how much to fertilize, and what kind of fertilizer to use, is to get a soil test. For help on how to do this through the Virginia Cooperative Extension, see this link. Soil testing should be done about every three years.
Perennials
Perennial plantings can rob the soil of its natural fertility. However, do not fertilize perennials heavily. If a perennial bed is amended with compost, further fertilization may not be necessary, which will be shown by a soil test. If additional fertilization is indicated, a light fertilization program using a 5-10-5 if available, or a balanced fertilizer such as 8-8-8 or 10-10-10, will provide a continuous supply of nutrients to produce healthy plants. Spread fertilizer in small rings around each plant in March or early April when the plant breaks ground. Avoid the crown and foliage. Repeat twice at 6-week intervals. This should be enough to carry plants through the summer. NOTE: Plants that are native to your particular locale, and which are suited to local environmental conditions regarding moisture, pH, and soil type, will likely need less or no additional fertilization.
Woody Plants
Generally speaking, the best time to fertilize woody plants is around the time they begin to grow actively. Most shrubs make active growth in the spring and early summer; it is good to fertilize them once around March or April. Some shrubs are described as preferring acid or alkaline soil, and there are fertilizers made specifically for plants that prefer acidic soil. Azaleas are an example of a shrub that prefer acidic fertilizers. A general fertilizer can be used as well. Look up fertilization recommendations specific to each plant. NOTE: As with perennials, shrubs that are native to your locale and suited to your environmental conditions, will likely need less or no additional fertilization.
Bulbs
Different sources give different recommendations for when to fertilize bulbs, discussed below. A general recommendation is to avoid using high-nitrogen fertilizers; instead, use a balanced fertilizer, such as 8-8-8 or 10-10-10, or a fertilizer made especially for bulbs. Avoid getting fertilizer granules on the foliage; for dense plantings, wash off foliage with a hose. The most important step is to first create a healthy soil by mulching with compost or well-composted manure to enrich the garden soil.
Timing
Virginia Tech recommends using two spring applications of a balanced fertilizer at a rate of 3 lbs. per 100 sq. feet. The first application is done when foliage first appears; the second is done after the bulbs have bloomed.
According to “The Bulb Blog” by the commercial bulb nursery, Brent and Becky’s, fertilizer should be added to the soil in the fall for fall-planted bulbs, and in the spring for spring-planted bulbs.
Another recommendation from The Garden Shed article, “Spring-flowering Bulbs,” is to fertilize in the spring after the flowers fade, and again in the fall at about the same time as you would plant new bulbs.
When considering these different recommendations, you may need to consider how practical it will be in the fall to locate your spring-blooming bulbs. If you have a bulb garden with mass plantings, you can certainly spread granular fertilizer in that garden in the fall. If your bulbs are scattered throughout your gardens, however, it is more practical to aim for spring fertilization after the foliage first appears. The option to fertilize in both fall and spring for a bulb garden seems feasible. The decision to choose one or two fertilizations in spring may be based on the vigor of your spring flowers.
SPRING LAWNCARE
These tips have been provided by The Healthy Virginia Lawns (HVL) program, a joint venture between the Virginia Cooperative Extension Master Gardeners and the Department of Conservation and Recreation. The program provides science-based lawn fertilization recommendations and other best management practices for homeowners, through site visits done by a trained Extension Master Gardener volunteer. For additional information and to fill out an application, please email one of the project coordinators, Melissa King or Khosro Aminpour, at healthylawnsalbemarle@gmail.com.
Fertilization
Before any fertilization program is adopted, a soil test should be done, at least every three years. See this link for information on soil testing. Homeowners frequently ask about using the convenient, widely available “step” programs developed for lawns throughout the season. Be mindful that the levels of nitrogen contained in the mid-spring and summer steps in the program often exceed the recommended levels that cool-season turfgrasses can efficiently utilize in the spring and summer months.  Another option for selecting fertilizers for spring treatments on cool-season grasses is to choose products that contain 50 percent or more water-insoluble nitrogen (often called “slow-release” nitrogen). Slow-release nitrogen is made available to the plant slowly either by way of controlled chemical or microbial decomposition. This provides a sustained growth response without a flush in shoot growth at the expense of the roots.
Keep in mind that, in most cases, fall is the ideal time for lawn fertilization. Â Turfgrass Frustration in Central Virginia/Garden Shed.
Weeds
Many of these step programs contain herbicides for weed control. Many formulations of “weed-and-feed” materials (products with a preemergent herbicide impregnated on a fertilizer carrier) are popular in spring lawn applications. If you select weed-and-feed materials with high percentages of nitrogen, choose sources that are predominantly slow-release nitrogen (as indicated on the label). Summer annual weeds (crabgrass, goosegrass, foxtail, etc.) are the most common targets for preemergent herbicide treatment in the spring, but many other grass and broadleaf weeds also germinate as soil temperatures warm and days grow longer. In mature turf, applications of broadleaf herbicides can be made as soon as the weed is actively growing. Typically, this will be when air temperatures are higher than 70°. Apply preemergent herbicides for crabgrass and other summer annual weeds when daffodils, forsythia, and dogwoods are blooming prolifically. If the primary weed problem consists of winter annual plants (weeds such as henbit, chickweed, or geranium) that have already flowered, then the herbicide will not reduce future populations since the weeds have completed their life cycle.
For more detailed instructions on issues such as applying herbicides when overseeding is also planned, see this article from Virginia Cooperative Extension, “Spring and Summer Lawn Management Considerations for Cool-Season Turfgrasses.”
For information on warm-season grasses see this article from VCE, “Spring and Summer Lawn Management Considerations for Warm-Season Grasses.”
For more information on how to adopt a more ecofriendly approach to lawncare, see past articles from The Garden Shed, “Responsible Lawn Care in the Era of Climate Change” and “Beyond the Lawn: Imagine the Options.”
COTTONY CAMELLIA SCALE ON HOLLIES
Late last spring/early summer, the holly bushes in our foundation plantings on either side of our front entrance were covered with wasps. It was a treacherous walk into the house for a couple of weeks. After researching the problem, I discovered that these white pests are cottony camellia scale (Pulvinaria floccifera), a soft scale in the shape of rod-like disks, commonly found on holly. The eggs hatch in late May through early June and the tiny new crawlers feed along the veins on the lower leaf surface. The scales develop through the summer and overwinter on twigs and branches. Â Usually a holly can tolerate cottony camellia scale without suffering much damage.
A large population of cottony camellia scale may, however, require treatment.  If your holly had major damage last year, you can spray a light-weight dormant horticultural oil in early spring to kill eggs that have overwintered. You can also use insecticidal soap early in the life cycle when the scales are in the crawler stage, usually in early-mid June (VCE recommends June 10-20.) Be sure to cover the bottom of leaves and interior leaves so that you cover all the eggs and crawlers while they are active. Once the scale has matured, horticultural oils and soaps will not be effective because the insects form a waxy coating to overwinter. Like most soft scales, cottony camellia scales suck out sap and excrete honeydew, a sweet, sticky liquid in which dark sooty molds often grow. The honeydew attracts wasps and other insects. The presence of black sooty mold will indicate a high population that may require treatment, but keep in mind that cottony camellia scale can usually be tolerated with no noticeable damage to the plant. It is when their populations become large and the plant strength is reduced that scale needs control. Or, when wasps become a problem!
INVASIVE SPOTLIGHT – GARLIC MUSTARD (GM)
Garlic mustard (Alliaria petiolata) has displaced native wildflowers such as spring beauty, wild ginger, bloodroot, trillium, and toothworts in many forested areas. This is because GM grows so vigorously in early spring and fall that it outcompetes them. GM is allelopathic, which means it releases toxins into the soil. These toxins hinder the growth of other plants species, and inhibit forest tree regeneration. Several butterfly species have become threatened because their wildflower hosts are now rare due to incursion by GM. Other butterflies are endangered because they lay their eggs on GM instead of on their host plants, and GM’s leaves poison their larvae. This plant is easiest to recognize after it produces white flowers in early April. Its foliage is also distinctive, and all parts of GM emit a strong garlic odor. This plant is a biennial that completes its entire lifecycle in two growing seasons. Its seeds germinate any time from spring to fall. Be mindful of how early GM blooms, and how quickly it sets seed. It is essential to remove garlic mustard before it sets seed. Once the flowers form seeds, any disturbance sends the seeds flying. Newly germinated seedlings may not be obvious at first because they may be buried in leaf litter. Always bag GM after pulling. Even after being pulled from the ground, a second-year GM plant continues to grow, flower, and set seed! See the factsheet from Blue Ridge PRISM (Partnership for Regional Invasive Species Management) for information on how to identify and eradicate this invasive. Blue Ridge PRISM also recommends this article from University of Massachusetts Amherst.
SOURCES
Tasks and Tips articles from past March issues of The Garden Shed:
2020, 2019, 2018, 2017, 2016
“Shrub Pruning Calendar,” Virginia Cooperative Extension, https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/430/430-462/430-462_pdf.pdf
“A Guide to Successful Pruning: Pruning Shrubs,” Virginia Cooperative Extension, https://www.pubs.ext.vt.edu/430/430-459/430-459.html
“Is It Time to Prune My Trees and Shrubs?” Clemson Cooperative Extension, https://hgic.clemson.edu/is-it-time-to-prune-my-trees-and-shrubs/
“Gardening by Month,” Missouri Botanical Garden, https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/gardening-by-month/march.aspx
“April Tips,” Virginia Cooperative Extension, https://albemarle.ext.vt.edu/content/dam/albemarle_ext_vt_edu/files/hort-tip-sheets/4-14-april-tips-perennials.pdf
“The Bulb Blog,” Brent and Becky’s, https://brentandbeckysblog.com/blogs/news/bulb-nutrition-and-how-it-works
“Spring and Summer Lawn Management Considerations for Cool-Season Turfgrasses,” Virginia Cooperative Extension, https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/430/430-532/430-532_pdf.pdf
“Spring and Summer Lawn Management Considerations for Warm Season Turfgrasses, Virginia Cooperative Extension, https://www.pubs.ext.vt.edu/430/430-533/430-533.html
“Spring Weeds,” University of Maryland Extension, https://extension.umd.edu/hgic/topics/spring-weeds
“Common Turf Weeds.” Virginia Cooperative Extension, https://www.pwcgov.org/government/dept/vce/Documents/Common%20Weeds.pdf
“Scale Insects on Holly,” Extension Ask An Expert, https://ask.extension.org/questions/248919
“Cottony Camellia Scale,” Fairfax County Master Gardeners, https://fairfaxgardening.org/cottony-camellia-scale/
“Cottony Camellia Scale – Shrubs,” University of Maryland Extension, https://extension.umd.edu/hgic/topics/cottony-camellia-scale-shrubs
“Rampant and Most-feared Invasive: Garlic Mustard,” Blue Ridge PRISM, https://blueridgeprism.org/wp-content/uploads/2017/06/Garlic-Mustard-Factsheet-5-27-17-VDOF-W-Box-FINAL.pdf
“Here’s the Dirt: The Newest Recommendations for Garlic Mustard Management,” ScholarWorks at UMass Amherst, https://blueridgeprism.org/wp-content/uploads/2019/10/Heres-the-Dirt_-The-Newest-Recommendations-for-Garlic-Mustard-Ma.pdf