Northern & Central Midwest
Don't Trim Bulb Foliage
Let spring bulb foliage yellow and wither before removing it. The leaves manufacture food that is stored in the bulb for next year's growth. Braiding or snipping the foliage of daffodils can reduce the food production of the leaves. Instead, plant perennials and ground covers that will grow and cover the yellowing leaves.
Prune Spring-Flowering Trees and Shrubs
Prune spring-flowering shrubs and ornamental trees immediately after they bloom. These include forsythias, viburnums, lilacs, small magnolias, rhododendrons, and azaleas. Prune to the ground old canes of forsythia and lilac. An alternative time to do renovation pruning is in late winter when plants are dormant. Deadhead (or lightly prune) spent lilac blossoms to increase flower production.
Watch for Aphids
Succulent new green growth is particularly susceptible to aphid attack. Monitor newly planted shrubs, small flowering trees, and succulent perennials for signs of aphids -- curled, distorted tip growth or sticky honeydew on the foliage. Spray a strong stream of water on damaged foliage to remove pests. If aphids are in center rosettes, use insecticidal soap.
Remove Strawberry Flowers
Remove flowers of newly planted June-bearing strawberries through the summer. This is necessary just for the first growing season to encourage the plants to develop a stronger root system. Also remove flowers for everbearing and day-neutral strawberries until July 1 when they can be left on the plants to set fruit for later in the season.
Plant Trees and Shrubs
Trees and shrubs should be planted this month. Plant on a cloudy day, early in the morning, to prevent heat and transplant shock. Water thoroughly and gently at planting time and continue for the first year with an inch of water a week, spread throughout the root zone. Mulch to conserve moisture.