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Gardening by Month

April Gardening Tips, Tasks, & Problems

Trees & Shrubs
  • As soil can be worked, trees and shrubs can be planted.
  • Remove tree wraps from trees now. 
  • Eastern tent caterpillars have started to make webs in the forks of branches this month. Control is not necessary, but small branches can be pruned off. 
  • Orange, jelly-like galls on junipers spread rust diseases to apples, crabapples, and hawthorns. Inspect for and dispose of galls on junipers before the orange jelly galls emerge. As apples, crabapples, and hawthorns bloom, apply preventative fungicides.
  • Fertilize established rose as needed once new growth is around 2 inches long. Use a balanced formulation, and, if needed, begin spraying for control of black spot.
  • Broadleaf evergreens may be showing signs of winter injury at this point, prune any dead and weakened wood.
  • Fluctuations in temperature can result in damage to the flower buds of plants such as hydrangeas and magnolias. 
  • Shrubs and trees best planted or transplanted in spring, rather than fall, include butterfly bush (Buddleja), dogwood (Cornus), rose of Sharon (Hibiscus), black gum (Nyssa), Vitex, redbud (Cercis), Magnolia, tulip poplar (Liriodendron), birch (Betula), Ginkgo, hawthorn (Crataegus), and most oaks (Quercus).
  • Winter mulch should be removed from roses. Complete pruning promptly. Lightly work in some compost once the mulch is removed. Only the dead wood from climbers should be removed at this time.
  • Some native trees blooming this month include flowering dogwood (Cornus florida), redbud (Cercis canadensis), serviceberry (Amelanchier spp.), oaks (Quercus spp.), and hickories (Carya spp.). Some ornamental trees blooming are crabapples (Malus spp.), Magnolias (Magnolia spp.), and cherries (Prunus spp.). 
  • Do not prune boxwoods before the last average frost date, April 15. Inspect for and treat boxwood leafminer as new leaves emerge. 
  • Evergreen and deciduous hedges may be sheared. Prune the top narrower than the base so sunlight will reach the lower limbs.
  • Prune spring-flowering shrubs after they finish blooming. These include Weigela, Viburnum, Rhododendron, and lilacs (Syringa).
  • If lace bugs were an issue on azaleas in the past and control is warranted, spray in early spring as soon as the eggs hatch when the nymphs are young.
  • Apply controls for holly leaf miner, if needed, when the new leaves are just beginning to grow.
 

Annuals & Perennials
  • When buying bedding plants, be sure to choose compact plants that have not begun to flower. 
  • Early through mid-April, hardy annuals can be transplanted outdoors. 
  • Ground covers can be mowed to remove winter damage and tidy the plants up. Raise the mower to the highest setting and water appropriately after. If a soil test indicates, fertilize as needed.
  • Transplant Virginia bluebells (Mertensia virginica) after they bloom but before the foliage disappears.
  • Easter lilies that are done blooming can be planted outdoors. Set the bulb 2-3 inches deeper than it grew in the pot. Mulch well if frost occurs.
  • Starting in late April, once the threat of frost is gone, summer bulbs can begin to be planted out: caladiums, gladioli, and cannas. 
 

Lawns
  • Start mowing cool-season grasses at recommended heights, usually between 1.5-3 inches.
  • Top-dress low spots and finish overseeding thin or bare patches.
  • Aerate turf if thatch is heavy or soil is compacted.
  • Apply crabgrass preventers before April 15th, usually around when forsythia are in bloom. Do not apply to areas that will be seeded or germination will be inhibited.
  • Cool-season lawns do not need fertilizer at this time of the year. Hold off on fertilizing zoysia lawns until May.
 

Fruits & Vegetables
  • Plants started indoors should be hardened off outdoors in a protected area before being transplanted into the garden.
  • Be sure transplants of vegetables such as broccoli, cabbage, and cauliflower, are in the garden by early April. Use balanced fertilizers, or fertilizers slightly higher in nitrogen as needed. 
  • A white interior latex paint may be brushed on the trunks of newly planted fruit trees to prevent sunburn. This will gradually weather off in time.
  • Start cucumber, melon, and summer squash seeds indoors by mid-April. 
  • Prune peaches and nectarines now.
  • Any cool-season fast-growing plants, like radishes and leafy greens, should be planted by early-mid April. Thin out crowded seedlings of cool-season crops such as beets, carrots, lettuce, onions, and radishes. 
  • Cool, moist springs are ideal for the transmission of apple scab. Spring wind and rain carry the spores to newly emerged leaves.
  • Asparagus and rhubarb harvests begin. Asparagus should not be harvested before 3 years from planting, and rhubarb should not be harvested until after the first year. Remove rhubarb flower stalks if they develop. 
  • Mid to late April, after the threat of frost, sweet corn and beans can be directly sowed outside. Protect if needed from cold temperatures. 
  • Seeds of luffa and hard-shell gourds can be started indoors in mid-late April. Soaking the seeds overnight before planting will help with germination.
  • Hold off on planting some warm-season crops like tomatoes, okra, and peppers, until mid-May.
  • Protect bees and other beneficial insects and don't spray insecticides on fruit trees that are blooming.
  • Thin out fruit of fruit trees like apples, pears, etc., as soon as fruits start forming. This will aid the branches from becoming too heavy later in the year. 
  • Peach leaf curl may start showing symptoms this month. Preventative fungicides can work if applied in fall, or before bud break in January-February.
 

Miscellaneous
  • Study your landscape for gaps that could be nicely filled with bulbs. Mark these spots carefully and make a note to order bulbs next fall. 
  • Look for morel mushrooms when lilacs bloom and the forest floor turns green.
  • Mount a rain gauge on a post near the garden to keep track of precipitation so you can tell when to water. Most gardens need about 1 inch of rain per week between April and September.
  • When transplanting starts, break off the rim of peat pots as they can act as a wick and draw moisture away from the roots.
  • Honeybees may be swarming. Notify a local beekeeper to find a new home for these beneficial insects.
  • Using watering devices like soaker hoses and irrigation systems can help save water and more effectively water plants by providing water directly to the base of the plants. It can also help reduce fungal foliage issues that arise from overhead watering. 
  • Hummingbirds return from their winter home in Central America.
  • Be sure to keep on top of weeds as they show up. Manually remove or use an appropriate herbicide as needed.
  • Frost is still possible this month. Be sure to keep an eye on temperatures and weather. Little can be done to protect larger plants, but small plants can be covered.
  • Carpenter bees may be seen buzzing around decks and other wood structures. Although males appear aggressive when defending their territory, they cannot sting. Females do not defend their nests but can sting if handled. 
  • Be sure to keep a distance from plants when weed whacking. Weed whips can be dangerous to plants, especially small trees by accidentally killing the bark at the base of the tree.
  • Enjoy, but do not disturb the many wildflowers blooming in the woodlands this month: spring beauty (Claytonia virginica), bloodroot (Sanguinaria canadensis), Dutchman's breeches (Dicentra cucullaria), Trillium spp., and dogtooth violet (Erythronium dens-canis). 
  • As your houseplants start actively growing, they can be fertilized with a balanced fertilizer. If using a houseplant fertilizer, follow label directions. If the fertilizer is not made for houseplants, be sure to use less than the recommended amount. 
  • Galls may be noticeable on various plants such as oaks, hackberry, and witch hazel. Galls are a normal part of plants and usually do not harm plants. Eriophyid mites are commonly responsible for these galls and do not require any control.