April

Indoors

  • Continue to care for indoor seedlings by providing sufficient light and water.
  • Begin to transition your indoor seedlings to outdoor climate increasing number of hours each day.
  • Start caladium tubers in moist sand or sphagnum at 65 degrees.
  • Cyclamen will go into their summer rest. Let them slowly dry off, set pots in a cool cellar, and water only enough to help the bulbs from shriveling.
  • Be careful not to let plants burn in south and east-facing windows.

Outdoors

  • Continue garden cleanup if not already done in March (see March listing).
  • Plant potatoes, peas, beets, turnips, radishes, carrots, spinach, and other leafy greens. Thin seedlings of previously planted carrots, beets, and lettuce.
  • Dig, divide, and replant perennials, such as helenium, fall asters, Shasta daisies, chrysanthemums, and phlox.
  • Plant pansies, forget-me-nots, foxglove, and other cool-weather flower transplants.
  • Sow seeds of sweet peas, bachelor’s buttons, and larkspur in flowerbeds.
  • Visit your local garden center for best selection of plants. Prepare a list to buy based on the location of planting (sunny, shady, part-shade, acid, dry, etc).
  • Protect transplants in the garden from cold and wind using milk jugs or other protective covering.
  • Plant roses, trees, and shrubs.
  • Starting a new lawn, fertilizing, or renovating a lawn with cool season grasses will be most effective if done during the peak growth period – from 65 to 75 degrees F.
  • Apply pre-emergence herbicides to prevent seeds from germinating (crabgrass and other weeds). Read label for application timing. Two applications may be required.
  • Late-flowering shrubs such as hydrangea, butterfly bush, althaea, franklinia, hould be pruned in spring, if pruning is needed.
  • Transplant strawberries so that the crowns are just even with the surface.
  • Fertilize blueberries with ammonium sulfate as well as rhododendrons, azaleas, and most other broadleaved evergreens.
  • Asparagus grows best in a sandy loam. Set the plants 1 to 1½ to 2 feet apart in rows 4 feet apart.
  • Remove cabbage worms as they appear, or treat for heavy infestation. Floating row cover is a good barrier if applied at time of planting.
  • Apply lime around lilacs and clematis, cultivating it into the soil.
  • Transplant cabbage, broccoli, lettuce, and cauliflower plants into the garden.
  • Mulch flower and landscape beds. To prevent weeds seeds from sprouting, put down wet newspaper overlapping edges underneath the mulch.
  • Near end of month plant a few gladioluses and continue every couple of weeks until early July to have continuous display.