It's pansy time, aka viola, violetta,; popular cool-season annual

Whether it's known as a pansy, viola or even violetta, flowering plants in the Viola genus are classic cool-season annuals; plants that can tolerate light frosts and continue blooming until summertime heat draws the curtain on their charming springtime show.

One of the best loved is the old-fashioned Johnny-jump-up (V. tricolor), a viola with dark purple upper petals and lower petals in shades of lavender-blue, yellow or white, often with dark purple markings, Plants are short-lived but readily self-seed, providing pleasurable discoveries of new plants in unexpected places each year.

Each year gardeners can also find new varieties of hybrid pansies (V. x wittrockiana) with flowers in new shades and sizes to grow. These new varieties are the result of cross breeding several Viola species. Flowers can be one color, bi-colored, or with more traditional pansy markings and coloration. Their flowers are often larger and plants more substantial than any of the parent plants.

Early this month, pansies, violas and many other cool-season annuals that have been hardened off can be moved outside for splashes of color in garden beds and containers, and ruffled skirts below spring-flowering bulbs.

Other projects for your garden in April:

General garden care

• Continue to remove all garden debris from last year. Shred and compost, leaving out all diseased material.

• Plant perennials, hardy ornamental grasses, and roses. When planting bare-root plants, soak the roots in a bucket of water for several hours before planting.

• Plant trees and shrubs; select disease-resistant varieties when appropriate. New plants take up to three years to become established. Mulch newly installed woody plants and irrigate during weeks with less than 1 inch of rainfall.

• If a layer of organic mulch was not placed last fall, add 2 to 3 inches to garden beds this month. Avoid placing mulch over crowns of plants. Pull mulch away from trunks of trees and shrubs.

• Crab grass control can be spread on lawns in early to mid-April before weeds germinate. For severe problems, a second application might be necessary in early June.

• Early in the growing season, renew efforts to discourage wildlife from forming browsing habits. Physical barriers are the most effective approach to preventing damage. One approach is placing three rows of black string no more that 18 to 24 inches apart around plants that are known favorites. Use spray repellents, as necessary, and reapply after periods of heavy rainfall.

Flowers

• Early in the month: plant cool-season annuals that can tolerate a light after they are hardened off. These include snapdragons, sweet peas, stocks, primroses, pansies, and more.

• Later in the month, plant Shirley, Iceland and California poppies, and Persian buttercups.

• If botrytis blight or bud blast was a problem last year, spray newly emerging peonies with an approved fungicide when plants are 2 to 4 inches tall. Avoid overhead watering. If fungus persists, consider relocating peonies to a more open, full-sun site in the fall.

• When peonies reach 10 inches, stake or hoop them to support their blossoms.

• Divide mature summer- and fall-blooming perennials when they are 4 to 6 inches tall. Do not divide Oriental poppies (July) or iris (late July) this month.

• Remove spent flowers of spring-flowering bulbs, but allow leaves to wither completely before they're removed. Fertilize bulbs only as needed. If properly planted bulbs are showing signs of decline (fewer, less showy blossoms), use a slow-release fertilizer in early fall.

• Divide clumps of older bulbs in need of rejuvenation when leaves begin to yellow. Replant in a sunny spot and water in well.

• Begin uncovering roses. Remove mulch and carefully hose away mounded soil. Avoid using sharp tools around bases of rosebushes. Apply a 6-2-0, organic, slow-release fertilizer.

Trees and shrubs

• If apple scab was a problem last year on crab apple trees, remove any remaining old leaves and fruits from branches and soil beneath trees. Prepare to start spraying with an approved fungicide as soon as the bugs begin to swell and open. Call Plant Information (847-835-0972) for recommended fungicides and timing for applications.

Fruits and veggies

• Plant small transplants of asparagus, carrots, cauliflower, lettuce, mustard, onions, peas, early potatoes, radish, rhubarb, turnips, and all other cool-season crops as weather permits.

• Plant midseason potatoes in mid-April.

• Later in April, begin to harden off warm-season vegetable transplants in a cold frame, or take flats of transplants outside to sunny protected areas, moving them indoors at night.

• Plant strawberries and pinch off first-year flowers to develop strong root systems.

Houseplants

• There is still time to sow seeds indoors for warm-season vegetables like tomato and pepper plants, and summer-blooming annuals. Most seeds take 6 to 8 weeks from germination to outdoor planting.

• If orchids have finished flowering, begin to fertilize regularly with a very dilute orchid fertilizer, or use fish emulsion with every watering.

Denise Corkery is a horticultural writer for the Chicago Botanic Garden.