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Garden Calendar for April
Contributor: David C. Zlesak
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Sweet peas are cool season crops that can be directly sown in the garden in April. David Zlesak After the soil thaws and temperatures begin to warm in mid to late April, one can begin to plant cool season crops. Sweet peas, peas, turnips, lettuce, and spinach can be directly sown in the garden and other plants such as pansies, kohlrabi, cabbage, snapdragons, and stocks can be planted as transplants. If the temperatures fall below the high 20's°F, consider covering to insulate young plants.

Assess pruning needs of deciduous shrubs in the spring and prune accordingly. Pruning is typically best done early in the month just as shrubs start to grow to minimize stress to shrubs and so you know what tissue is alive and dead. Remove dead branches, thin out overcrowded, rubbing branches to open the center of the plant for better air circulation, and head back overly long branches to produce a more symmetrical, balanced plant. Rejuvenation pruning is a common pruning technique used on shrubs to keep them growing strongly. It involves every or every other spring removing some of the oldest canes all the way down to the base or near the base of the shrub to promote vigorous new replacement canes. Rejuvenation pruning is especially useful for lilacs and hardy roses to keep their size manageable and to help keep plants blooming strongly. Early flowering shrubs like forsythia, flowering quince, and lilacs are often pruned after flowering so as to not miss out on some of the much anticipated blooms.

Stems from last season of herbaceous perennials Rudbeckia fulgida are often more brittle and easy to remove in spring. David Zlesak Gradually remove winter mulch from covered perennials. Old stems of herbaceous perennials from last year that may still be in place should be removed. Such stems are often more brittle in the spring than the previous fall and are easier to break off and remove. When removing old stems of herbaceous perennials in the spring, do so before new, emerging stems progress too far so they are not damaged in the process.

Many municipal compost sites reopen in April. Check with your local site for hours and the services provided. Some sites accept only non-woody plant debris, while others also accept woody brush. Many sites also provide free compost and wood chips while supplies last.

There is still time to start seeds indoors of fast-growing, warm-season annuals like tomatoes, zinnias, and marigolds for planting outside the end of May or early June.