If we need to “stay at home,” what better place to do that than in a garden! Early April is still erratically cool, and so we are obliged to stay busy, which is what we want to do anyway. The gyms are closed but we can pick up a hoe and a rake and a shovel and get all the activity we need. We’re in our special place and that gives us a lot to be thankful for. The signs of budding life in April gives comfort and hope. And though we can’t yet share plants, we can share photos and that’s fun too.
What tasks should we undertake to get our gardens ready for the season?
GENERAL TASKS
Continue tasks outlined in The Garden Shed March issue to do list and tackle new tasks:
- Clean up flower beds and borders.
- Cut back dead stems and foliage from perennials that were left standing over the winter.
- Pull weeds.
- Redefine flower bed edges with a nice clean edge using a flat-edged spade or edging tool.
- Clean under and inside of shrubs that tend to be leaf-catchers before the plant makes its new leaves.
- Top dress flower beds with one inch of compost. The compost improves the soil structure and adds nutrients and moisture-holding capacity.
- Gently move back winter mulch from around plants as soon as growth starts in the spring.
- As a general rule, late-summer or fall-flowering perennials are planted in spring, but check guidelines specific to each plant.
- Set cages over emerging peonies.
BULBS
- Fertilize spring-flowering bulbs after they finish blooming. An organic fertilizer especially formulated for bulbs is a good choice, or a 5-10-10 fertilizer (lower in nitrogen). Keep fertilizer off the leaves and away from roots to avoid burning.
- Remove faded flowers from daffodils, tulips and hyacinths to prevent seed formation. Seeds take stored food from the bulbs.
- Let the foliage die naturally. Green leaves produce food for plant growth next year. After leaves turn yellow, cut and remove the stems and foliage of the plants. Don’t braid or tie up the foliage since this could interfere with photosynthesis for food production.
- If daffodils have become crowded and aren’t producing as many flowers as in past years, they need to be divided. Wait to do this until after the foliage has died back later in the summer. Bulbs dug and moved before foliage fades may not bloom for several years. Mark the location of the clump with a golf tee, plastic knife, or a tent stake to mark the spot.
- Divided daffodils should be planted in late spring to early summer. Before July 4th is an easy-to-remember target date.
- Identify spots now where you want to add additional daffodils, tulips, hyacinths, crocus or other spring-blooming bulbs next fall. Tent stakes work well as markers and can be a helpful physical aid to pictures.
- Don’t forget to cut some daffodils or tulips to enjoy inside!
- Set out summer-flowering bulbs in the spring after danger of frost is past. Summer-flowering bulbs include amaryllis, canna, tuberous begonia, caladium, crocosmia, dahlia, and gladiolus.
FERTILIZATION
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 gives a continuous supply of nutrients to produce healthy plants. Use 5-10-5 fertilizer. 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.
Generally speaking, the best time to fertilize landscape 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. A general fertilizer can be used as well. Look up fertilization recommendations specific to each plant.
 PRUNING
Several early spring-blooming shrubs familiar to our landscape are ready for pruning in April after bloom is done: daphne , forsythia (Forsythia x intermedia), winter jasmine (Jasminum nudiflorum), flowering quince (Chaenomeles japonica), pussy willow (Salix discolor), and witchhazel (Hamamelis vernalis). Fall-blooming witchhazel (Hamamelis virginiana) is also pruned in early spring.
For the above shrubs, flowers are produced on wood from past season, and begin setting buds for flowering next year soon after blooming. For a listing of other shrubs that can be pruned in early spring, take a look at the helpful Shrub Pruning Calendar published by the Virginia Cooperative Extension, Va.Coop.Ext. Pub.No. 430-462.
SEEDS AND SEEDLINGS
- Harden off seedlings when transplanting them to the outdoors. Place them in a shady location initially and bring them indoors at night if temperatures are predicted to drop below 50°F. For advice on transplanting seedlings, see the Virginia Cooperative Extension article, “Plant Propagation from Seed.”
- Transplant on a shady day in late afternoon or in early evening. Water with a half-strength fertilizer solution.
- When transplanting seedlings in peat pots, break away the uppermost rim of the pot before planting and make sure the pot is completely covered with soil. If the rim is above the soil level, it will act as a wick and draw moisture away from the transplant.
- Sow seeds directly outside after checking planting directions on seed packets. For example, some seeds should not be planted until after the last frost; some can be planted 1-2 weeks before the last average frost date.
NOTE ON LAST AVERAGE FROST DATE
As noted in the March issue of The Garden Shed, “March in the Vegetable Garden,” the last average frost dates have changed by 2-4 weeks, which will greatly impact when we can plant vegetables and ornamentals.
In a concession to climate change, 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. This 2-4 week earlier final frost can significantly affect when we plant specific vegetables.
 LAWNS
Many home owners have questions about lawn fertilization. Fall fertilization to promote root growth is the most beneficial. Spring is one of the trickiest times to optimize nitrogen (N) fertilization. Cool-season grasses have their most significant period of root development in the spring, so some N is beneficial. High rates of N promote a lush, dark green lawn, but there is too much emphasis on shoot growth rather than roots, and this often leads to serious problems with disease, insects, or drought later in the year. Warm-season grasses don’t initiate much root growth until after shoot greening is complete, so the ideal scenario is to wait at least until 50-75% green-up before applying, and apply after the last frost. For more detailed information, see the Virginia Cooperative Extension publication and podcast, “Spring Lawn Fertilization–Getting It Right.” Another helpful VCE publication is “Lawn Fertilization in Virginia.”
Get a soil test to determine how much fertilizer is needed. Nitrogen is soluble and is not measured on a soil test because the percentages are so unstable. The assumption of the lab is that nitrogen needs to be replaced each growing season. The nitrogen recommendation is made specifically for the plants or crops you plan to grow.
You also need to check the pH level provided on the soil test. Proper pH is necessary for grass to absorb nutrients. Fertilization is not even effective if the pH isn’t correct. You may discover that you need to adjust the soil pH by adding lime. Soil in our area is often acidic, and adding lime makes it more basic. The ideal pH for a lawn is 6.2-7.3. On a scale of 0-14, 7 is neutral. Less than 7.0 is more acidic. Greater than 7.0 is more basic. As an example, our soil test this year showed that the front lawn area had a pH of 6.0 and the back lawn had a pH of 5.5. Both of these areas are too acidic and require lime applications. Lime applications change the pH incrementally and need time to take effect. Follow the recommendations for the soil test; don’t try to change the pH in one application if that’s not recommended. It takes patience.
For mowing, keep the mower height at about 3” early in the season to store food. Aerate turf if soil is compacted.
HOUSEPLANTS
- Adjust amounts of water and fertilizer as your indoor plants get more window light.
- Move your houseplants outside once night-time temperatures consistently stay at 50° F. or higher.
- Repot any root-bound plants into slightly larger pots. Fertilize with a slow-release fertilizer.
- Place the plants in a shady area initially so that they can gradually acclimate to being outside.
FUNGII AND CATERPILLARS
There are several closely-related rust diseases that require two hosts to complete their life cycle. All three rusts can infect most varieties of eastern red cedar (Juniperus virginiana) as well as many other junipers, and a second host from the Rosaceae family. In spring, look for orange, jelly-like galls on cedar trees that spread rust diseases to apples, crabapples, and hawthorns. These galls do not impact the overall health of the cedar, but the second plant family in the cycle such as apples and crabapples may need to be treated with a preventative fungicide at bud break. Immunox is identified as an effective fungicide to protect against rusts. For an excellent presentation on cedar apple rust, see this short video from the Kansas Dept. of Wildlife, Parks and Tourism.
Eastern tent caterpillars (Malacosoma americana) overwinter as eggs and the young larvae hatch at or before bud break in March or April. The young larvae gather near the fork of the tree limb to begin spinning their web or tent. Eastern tent caterpillars are primarily found on black cherry, crabapple, and apple trees. They are a favorite food of the yellow-billed and the black-billed cuckoo. Manual methods for removal of the tents are usually sufficient. Egg masses on trees can be removed in winter. Natural controls include predaceous and parasitic insects (especially wasps), and disease organisms. Bacillus thuringiensis (Bt, Dipel or Thuricide) is a safe biological spray if an insecticide is needed and should be applied as soon as the tents appear. Trees usually recover from lost foliage unless the tree is young or weakened and stressed from other problems.
MISCELLANEOUS “TASKS”
- Mount a rain gauge on a post or in the ground so you can monitor moisture; most gardens need about 1” of rain per week during the growing season.
- Welcome back, Ruby-throated hummingbirds! Males will return from their winter home in Central America around mid April. The females usually follow in May. See the May 2019 edition of The Garden Shed, “Gardening for Hummingbirds.”
- Add plants that will attract birds to your landscape. See the February 2019 edition of The Garden Shed, “Creating a Bird Friendly Garden.”
- Build a monarch station in your backyard. See the May 2017 edition of The Garden Shed, “Saving America’s Iconic Butterfly from Extinction.”
- Consider adding low-growing, native plants or sedges in bare areas where you ordinarily mulch, such as between shrubs in foundation plantings, or along paths.
- Swap out one nonnative plant with a native plant.
- Add edibles to your ornamental garden or to foundation plantings.
- Check yourself for ticks each time you come in from working in the landscape. Virginia’s tick season generally picks up in April with summer months being the worst. This year’s winter was very mild which means ticks will be very active.
Check out the Monthly Gardening Tips section now located under Gardening Resources on the main page of the PMG website: https://piedmontmastergardeners.org/gardening-questions/monthly-gardening-tips/#April
For additional information on April Tasks ad Tips, consult previous issues of The Garden Shed:
SOURCES:
Bringing Nature Home (Douglas W. Tallamy, 2009)
Eastern Tent Caterpillar, Virginia Cooperative Extension (VCE), https://www.pubs.ext.vt.edu/444/444-274/444-274.html
Gymnosporangium Rusts, VCE, https://www.ppws.vt.edu/extension/plant-disease-clinic/disease-advisory/201505-Gymnosporangium_Rusts.html
Cedar Apple Rust, Kansas Dept. of Wildlife, Parks and Tourism, https://www.youtube.com/watch?v=zfsMoqLF18k
March and April: Spring in the Yard, Lewis Ginter Botanical Garden, https://www.lewisginter.org/march-and-april-spring-in-the-yard/
Mow Like a Pro, VCE, https://ext.vt.edu/lawn-garden/turfandgardentips/tips/mowing.html
“Ruby-throated Hummingbirds Blog,” The Wildlife Center of Virginia, https://www.wildlifecenter.org/blog/ruby-throated-hummingbirds-blog
Perennials: Culture, Maintenance and Propagation, VCE, https://www.pubs.ext.vt.edu/426/426-203/426-203.html
“Spring Lawn Fertilization—Getting It Right,” VCE, https://ext.vt.edu/lawn-garden/turfandgardentips/tips/spring_fertilization.html
“Lawn Fertilization in Virginia, VCE, https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/CSES/CSES-135/CSES-135-pdf.pdf
Factsheet, Home & Garden Information Center, Clemson University, https://hgic.clemson.edu/factsheet
Flowering Bulbs: Culture and Maintenance, VCE, https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/426/426-201/426-201_pdf.pdf
“Eastern Tent Caterpillar,” Entomology at the University of Kentucky, https://entomology.ca.uky.edu/ef423
“Tent Worms,” Cornell Cooperative Extension, St. Lawrence County, http://stlawrence.cce.cornell.edu/resources/tent-worms