Extension Educator, Horticulture
Spring is finally here. With each ray of sunshine another plant explodes out of the earth. They never seem to pop up right where my internal GPS said they should. I'm convinced they all move a bit without saying "Mother May I." Someday I will catch them and send them all back to the start. Dividing perennials is always high on my "to do" list. If you are wondering what should be your priority this year, here are your activities for April. Get out your red pen and start checking.
Average last frost date is approximately April 21. For tender plants such as impatiens, basil and tomatoes, wait until after May 10 before planting.
___Begin planting and dividing most perennials except bearded iris and peony. Iris are divided in August. Peonies are divided in September.
___Plant pansies and hardy annuals.
___Finish pulling back mulch from perennials and roses.
___Prune summer and fall blooming clematis.
___Spray emerging peonies with fungicide if diseases such as botrytis have been a problem.
___Plant bare root plants while dormant. Soak plants in warm water for at least 2 hours before planting.
___Ornamental and native grasses should be cut down within a few inches of the ground before growth starts.
___Houseplants and overwintering tropicals can be trimmed, repotted and fertilized. Wait until after May 10 to place outside.
___Prune sage, butterfly bush, Russian sage and Caryopteris down to about 8 inches to stimulate growth. Wait until lavender shows new growth before pruning.
___Mow lawn to 2 inches removing no more than 1/3 of leaf blade at any one mowing.
___Establish or renovate turf by seed or sod. Prepare soil properly and get good seed to soil contact. Select turf mixes and blends appropriate to site and maintenance practices.
___If appropriate, apply preemergent crabgrass control to problem areas when the soil temperatures reach 50 degrees F for at least three consecutive days (generally mid-late April). Do not reseed turf at the same time.
___Use postemergence herbicides for actively growing broadleaf weeds if necessary. Consider spot treatment rather than complete lawn application. Read and follow all label directions.
___Reduce thatch if more then .5 inch by using core aerifiers or vertical mowers.
___Core aerifiers will also reduce soil compaction.
___Continue planting trees and shrubs.
___Prune spring flowering shrubs such as forsythia soon after bloom. Use renewal pruning by removing oldest stems at soil level.
___Prune out and remove all dead and diseased wood.
___Fertilize if not done in fall and if soil test or reduced growth indicates need.
___Scout for spider mite damage on spruce by shaking leaves over white paper. Mites will look like periods with legs.
___Begin fungicide treatments for apple scab on crabapples if it has been a problem in the past. Consider replacing trees with disease resistant cultivars.
___Add compost to garden.
___If needed, till garden. Squeeze a handful of soil. It should crumble apart easily. Do not work when soil is too wet.
___Plant seeds of frost tolerant plants such as spinach, lettuce, carrot, beet, chard, parsnip and radish.
___Plant or divide rhubarb.
___Plant asparagus crowns.
___Remove straw from strawberry patches.
___Plant strawberries. Pinch off first year flowers to encourage strong root systems.
___Plant fruit trees, grapes, raspberries and blackberries.
Spring Wildflowers Telenet, April 21 at 7:00 p.m. through U of I Extension distance learning system at