April Gardening Tips

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Annuals and Perennials

  • Cut ornamental grasses back to a height of 6 inches before new growth appears.
  • Cut buddleia, Russian sage, and Montauk daisies to a height of 8-12 inches.
  • Prune lavender to 1/3 of its height once new growth appears.
  • Prune old, leggy growth from heather (which flowers on new growth in late summer) but prune heath (which sets its flower buds in late spring) just enough to shape it in the early spring.
  • Pull back mulch from perennials to allow the soil to warm up but be prepared to temporarily cover them if heavy frosts are predicted.
  • Start dahlia tubers in pots indoors in a cool, bright spot. Cover tuberous roots with 2 to 3 inches of potting mix. Pinch back tips when they reach 6 inches and transplant outdoors when the ground temperature reaches 60° F..
  • Get the jump on weeds in garden beds by pulling out any that overwinter and applying mulch.
  • For an instant spring show, fill containers with purchased forced spring bulbs from supermarkets and garden centers.
  • Freezing temperatures don’t harm pansies, but if they have been grown in a greenhouse they should be gradually exposed to outdoor temperatures before planting.
  • Keep Easter lilies in a moist and brightly lit location. They can be planted in the garden after the danger of frost.
  • Divide overcrowded summer or fall blooming perennials.
  • Hardy water lilies may be planted in pools in spring but wait until the water reaches 70° for tropical water lilies.
  • Place peony supports.
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Education and Events

Houseplants

In the Vegetable Garden

  • Weather permitting, direct sow​ ​peas, ​carrots, ​radishes, ​lettuces, ​and​ ​spinach every two weeks through mid-May for staggered harvests.
  • Plant​ ​seedlings​ ​of​ ​cauliflower, ​cabbage, ​and broccoli once weather settles..
  • Purchase onion sets for planting and set 1 inch deep and 4 to 5 inches apart when soil can be worked.
  • Extend the season by speeding up the warming of soil on garden beds by covering the beds with black plastic for a few weeks.
  • Place seedlings in cold frames around April 25 or later to harden off.
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Insects

  • Apply sprays as needed to control insect pests and diseases on apple , peaches and nectarines, pear, and plum trees if the temperature is over 40°F.
  • Check​ ​fruit​ ​trees​ ​for​ Eastern ​tent​ ​caterpillars, ​they​ ​emerge​ ​around​ ​the​ ​same​ ​time​ as ​leaves​ ​sprout.​ ​Blast​ ​nests​ ​with a​ ​strong​ ​spray​ ​of​ ​water​ ​to​ ​destroy​ ​them.
  • A new generation of spongy moth caterpillars will hatch in late April and begin feeding on the leaves of many tree species. Remove and destroy any egg masses you find on your trees.
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Landscape and Lawns

Fruits

Lawns

  • Dead spots in the lawn can still be renovated in early April. Top dress bare areas with a mix of topsoil and compost, reseed, and keep moist until germination.
  • Apply pre-emergent crabgrass weed control when the forsythia blooms.
  • Do not use a pre-emergent weed control if you are trying to germinate grass seed.
  • Early spring is a great time to spot spray or hand-dig dandelions. If spraying, choose a product that won’t kill grass. If digging, wait until after a rain, when soil is soft.
  • Prune back bedraggled looking ground covers and fertilize lightly after April 15.

Trees and Shrubs

  • A new generation of spongy moth and eastern tent caterpillars will hatch in late April and begin feeding on the leaves of many tree species. Remove and destroy any egg masses you find on your trees.
  • Spongy moth egg masses are buff-colored and may be found on trees, stones, fences, lawn furniture, and other protected places.
  • The eggs of the eastern tent caterpillar are deposited in brownish masses, resembling a large raisin squeezed around a twig. Scrape off the egg masses and crush underfoot or drop into a pail of detergent and water.
  • Complete​ ​removal​ ​of​ ​diseased, ​weak, ​or​ ​crossing​ ​branches​ ​on​ ​shrubs​ ​and​ ​small​ ​trees.
  • Celebrate​ ​Arbor​ ​Day​ ​on​ ​April​ ​29th​ ​by​ ​planting​ ​a​ ​tree. Choose planting sites based on exposure to sun, shade, wind and distance from water source.
  • Remove any remaining leaves from last summer on roses and spread a thin layer of new mulch underneath them. This will help prevent the spread of any diseases that may have over-wintered.
  • Spread​ ​fertilizer​ ​under​ ​apple trees as buds swell and open.

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Wildlife

  • Check for raised mole tunnels in the yard and plan to put down a grub control product as necessary (the presence of moles does not mean there is a grub problem) between mid-June and mid-July.
  • Set up a bat house early in the month to encourage them to roost. Visit the DEEP’s Bats fact sheet for information and bat house plans.
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Yard Accessories and Miscellanea

  • Set up 1 or 2 rain barrels at downspouts to water garden beds, flower beds, and containers.
  • When filling large containers for the deck or patio, save on soil by creating a false bottom. Most smaller container plants don't need more than about a foot of soil depth for their roots. Keep the plant in a smaller pot that is supported by an inverted pot or rocks.
  • Don't skimp on potting soil, however, for larger plants as their roots will fill the pot.
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Despite good cultural practices, pests and diseases at times may appear. Chemical control should be used only after all other methods have failed.

For pesticide information please call UConn Home and Garden Education Center weekdays, in Connecticut call toll free 877-486-6271. Out of state call 860-486-6271

Revised by the UConn Home and Garden Education Center 2017

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, the Dean of the College, Cooperative Extension System, University of Connecticut, Storrs. The Connecticut Cooperative Extension System is an equal opportunity employer and program provider. To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, Room 326-W, Whitten Building, Stop Code 9410, 1400 Independence Avenue, SW, Washington, DC 20250-9410 or call (202) 720-5964.