April Garden Calendar

Garden Help Desk

Master Gardeners will take your gardening questions at the Virginia Cooperative Extension Help Desk year-round. Call us at 703-324-8556 or email us at mgfairfax@vt.edu. We will return to the farmers markets in May.

Home Turf

Home Turf, a Virginia Healthy Lawns Program, will accept applications from homeowners this month. For more information, see the Home Turf page under “Programs” on this website.

Trees & Shrubs

Pruning
Here is a partial list of trees and shrubs that may be pruned in April. Hire a certified arborist to prune the larger trees. Prune all dead, damaged or diseased branches any time of the year.Deciduous trees: ash, bald cypress, beech, catalpa, ginkgo, hickory, honey locust, mulberry, black gum, stewartia, sweetgum, sycamore, tulip tree, zelkova.

Evergreen trees: cedar, cypress, fir, hemlock, juniper, Leyland cypress, pine, spruce.

Shrubs: arborvitae, boxwood, camellia japonica, camellia sasanqua, cherry laurel, euonymus, forsythia, juniper, privet, quince, witch hazel.

Planting
Early April is a great time to plant just about any tree or shrub. If you are planting a container-grown or balled-and-burlapped (b & b) tree or shrub, the diameter of the planting hole should be at least three times the diameter of the root ball of your plant. If your soil is especially compacted, the diameter of the hole should be five times the diameter of the root ball. Make sure you do not plant too deeply. Mark with tape where the top of the soil in your container meets the trunk of your plant. This point should be 1/2 to 1 inch above the top of the backfilled soil.

For b & b (ball & burlap) plants, remove the burlap and any wire that was used to hold the root ball together. When you remove your specimen from the pot or the b & b material, cut out any roots that circle the inside of the pot or turn upward from the bottom. Comb the roots with your hand cultivator or similar tool to remove as much of the planting medium as you can.

Spread the roots out in the planting hole. For most plants and shrubs, refill the hole with the native soil. As you backfill, add water to make sure the soil fills evenly around the roots. Check several times to make sure the plant is not too deep.

Water the plant frequently, and keep watering during the hot, dry periods of summer.

Lawn

Aeration
If your soil is dry enough, this is a good time to aerate your soil. Hire a company to do it, or rent a core aerator. Follow the aeration with a top dressing of compost.

Mowing
Your grass will need mowing this month. If you have a mulching mower, leave the nutrient-rich clippings on the grass. They will decompose and return nitrogen and other nutrients to your soil.

Crabgrass prevention
Apply pre-emergent weed control material in early April, depending on the temperature. Do NOT buy a combination weed-and-feed product. The right time to apply crabgrass preventer is the wrong time to add fertilizer to your lawn.

Lime
If you didn’t lime in the fall, apply it this month. It takes most of a year for ground limestone to have its full effect on raising pH. Test your soil first to determine if it needs lime. Soil test kits are available at public libraries in Fairfax County.

Seeding
If you still have bare spots in your lawn, early spring is a good time of year for spreading grass seed. It will germinate and come up strong in the spring. Keep your newly sprouted lawn watered to survive our hot, dry summers.

Vegetables

Seed starting
For more information on starting seeds indoors, see Starting Seeds Under Lights. Tomato seeds should be started inside in early April for transplant outside in early to mid-May.

Working the soil
It’s tempting to start digging in the garden on nice days in April, but you must take care not to compress wet soil. This causes compaction that ruins soil structure. Pick up a handful of soil, and squeeze it into a ball, then drop it from a height of 3 feet. If the ball shatters into many pieces, the soil is dry enough to be worked. If it keeps its shape or maybe breaks into a few large pieces, it is too wet to be dug.

Cool season crops
Transplant or start cool season crops outdoors. These are the vegetables that tolerate light frosts, and include radish, peas, onions, cabbage, broccoli, and leafy greens like kale, lettuce, collards, and spinach.

Raised beds and cover crops
You can cheat a little bit on working wet soil if you have raised beds, because you will not be standing in the beds while you dig them. If you have a cover crop such as annual rye, you will need to begin to turn the rye into the soil in early April to give it enough time to decompose and return its nutrients to the soil before you plant that bed in May. Turn it with a shovel first, and finish it off with the rototiller a couple of weeks later.

Fruits

Most spray programs to control insects and disease should be underway in April in our area. For details, consult the 2019 Virginia Pest Management Guide, Home Grounds and Animals, Section 3: Home Fruits: Disease and Insects. Home Fruit

Flowering Annuals, Perennials

Many annual flowers can be started inside under the lights to get an early start on the growing season. Cosmos, zinnias, nasturtiums, gomphrena, geraniums and sunflowers are good candidates.

If you are buying bedding plants for your garden, look for ones with many unopened flower buds. They will produce flowers quickly. Check to see if the roots are small and weak. If they totally fill the container, put it back. Find plants that have healthy, sturdy roots that are not growing around the inside surface of the container.

Houseplants

Scouting for Pests
Inspect houseplants regularly for possible pest problems. This month, you may begin to see small numbers of aphids, whiteflies, mites or mealy bugs. Keep the problems in check by bathing the plants in a spray of warm water or water containing an insecticidal soap. Make sure to wet all parts of the plant thoroughly. A cotton swab dipped in rubbing alcohol is good for removing small numbers of mealy bugs and aphids.

Watering
Most houseplants should be watered when the surface of the soil feels dry. Add water until it runs out the bottom of the pot. If the soil has pulled away from the pot’s rim, it is much too dry. Soak the pot in a bucket of water to restore the proper moisture.

References
A Guide to Successful Pruning, Shrub Pruning Calendar, 2009, VCE Publication 430-462
A Guide to Successful Pruning, Deciduous Tree Pruning Calendar, 2009, VCE Publication 430-460
A Guide to Successful Pruning, Evergreen Tree Pruning Calendar, 2009, VCE Publication 430-461
Maintenance Calendar for Cool Season Turfgrass in Virginia, VCE Publication 430-523
Indoor Plant Culture, VCE Publication 426-100
Home Fruit: Diseases and Insects, 2019, Virginia Pest Management Guide, Home Grounds and Animals