University of Maryland Extension

April Tips & Tasks

Back to Gardening Tips & Tasks

cedar apple rust gall on an evergreen

Outdoor Garden and Yard Tips

  • Cedar-apple rust disease forms its galls on Virginia cedar (Juniperus virginiana) in April. The odd-looking galls are at first bright orange gelatinous balls with long “horns” or projections; they later turn brown and become hard. They are the alternate host structure for a disease that does very little harm to the junipers but can be quite destructive to apple trees, hawthorns, and quince.

  • Continue planting and transplanting trees and shrubs.  Choose quality trees: shade trees should have a single, straight trunk. Planting and transplanting should be completed before the end of June.

  • Viburnum leaf beetle is a serious pest of native arrowhead viburnum, cranberry bush, and many others. Look for feeding damage on viburnum and yellow larvae. Control them promptly since they can defoliate plants. Repeated defoliation can result in the death of native viburnums.

  • Spotted lanternfly eggs will start hatching late April or early May depending on the weather.

  • Plant a butterfly garden – Butterflies add beauty and help pollinate flowering plants. A variety of nectar plants for adult butterflies and host plants (food) for the caterpillars will attract them. Milkweed species is a popular nectar and host plant for the Monarch butterfly.

box turtle in grass

  • Eastern box turtles and various species of snakes are coming out of hibernation and may visit your yard. Box turtles are becoming scarce through much of Maryland because of road mortality and habitat destruction. Observe it but leave it in the wild.

  • Many spring bulbs have fully emerged and are flowering. Remove spent flowers but leave the green bulb foliage alone until it yellows and dies back naturally.

  • Lawn mowing season begins in April. The height and how frequently you mow your lawn is very important. Cool season grasses such as tall fescue and bluegrass should be maintained between 3 - 4 inches for most of the growing season and no more than 1/3rd of the leaf blade should be removed at each mowing.

cold damaged tomato
Catfacing on tomato

  • Set out warm season crops after the danger of late frosts. Cool night temperatures in April will cause the first tomato fruits to become deformed or “catfaced”. Be prepared to cover tender transplants with paper bags, blankets or other materials like floating row cover if frosts are anticipated.

  • “Harden-off” transplants one week prior to transplanting to toughen the plants and ready them for outdoor conditions. 

  • Cut fall-planted cover crops (rye, wheat, hairy vetch, crimson clover) at ground-level and cover with a black weed barrier or tarp for 2-3 weeks to kill the cover crops and prevent re-growth The residues create a mulch you can plant into (no-till gardening).

    .

  • Plant tree fruits and small fruits when weather and soil conditions are favorable. Fruits that require little or no spraying include figs, Asian persimmon, Asian pear, blueberry, blackberry, raspberry, strawberry, and currant.
     
  • Test your soil before planting blueberries. The desired soil pH for blueberry is 4.3-5.3. Use iron sulfate and elemental sulfur to drop the soil pH, a process that can take 6-12 months. These plants establish more quickly when a generous amount of compost is worked into the soil.

 Indoor Plant and Insect Tips

fungus gnat adult

Adult fungus gnat

  • Groom houseplants by removing dead and diseased foliage or spent flowers; this reduces insect and disease problems and improves their appearance. Gently dust the leaves with a soft rag. If possible, periodically place your plants in the shower to remove dust and to give them a good drink of water. This can revive a tired houseplant and helps to leach soluble salts (from fertilizers) from the soil.

  • Fungus gnats are small, harmless black flies that hover around, breed in and feed on moist growing media. Be careful not to over-water houseplants. Growing media should be allowed to dry out before watering again.

  • Different types of foraging ants may appear in your home. Try using bait stations to control minor infestations. Liquid and gel formulations are usually quite effective.

Maintained by the IET Department of the College of Agriculture and Natural Resources. © 2020. Web Accessibility

University programs, activities, and facilities are available to all without regard to race, color, sex, gender identity or expression, sexual orientation, marital status, age, national origin, political affiliation, physical or mental disability, religion, protected veteran status, genetic information, personal appearance, or any other legally protected class. If you need a reasonable accommodation to participate in any event or activity, please contact your local University of Maryland Extension Office.