Trees / Shrubs –Prune overgrown shrubs at this time. Careful removal of one third of the thick woody stems will rejuvenate multi-stemmed shrubs like spirea, forsythia and honeysuckle for more bountiful blooms next year.
Flowers – May is planting time for bedding plants. Watch weather carefully and follow your average “frost free” date for your area to know when is the best time to plant. Annual flowers give the most impact if they are planted in masses or groups. Buy plants that have good colored foliage and are stocky plants. When you have a choice, fewer plants per pack result in less transplant shock & quicker cover.
Lawns – For people wanting a care free-way to determine timing for fertilizer application, try the “holiday” method. Fertilize four times; (not more than 1 lb. of nitrogen each time) Memorial day, Fourth of July, Labor day and Thanksgiving.
Vegetables and Fruit – Begin preparing for fruit pest control before bloom and after. Follow recommendations of insect and disease control products carefully to avoid killing beneficial organisms.
Pesky Bugs – Mosquito reproduction skyrockets in the spring especially in areas where there is standing water. To eliminate breeding sites be sure to replenish water sources daily such as birdbaths, and dog dishes. Avoid puddles in your landscape as much as possible.
Planting – Plant bare root, balled and burlapped, balled and potted, and container-grown ornamental landscape plants. Bare root plants should be dormant. Spring has become a traditional time for planting because environmental conditions favor planting. Soil and air temperatures should be above freezing. Plants adapt readily to the intensity of spring sunlight and are less likely to be stressed by dry weather.
Transplanting – Dig plants that were root pruned in the fall. Deciduous plants may be moved bare root before bud break, but broadleaf and narrowleaf evergreens should be moved balled and burlapped or balled and potted. Moving may be done whenever soil and air temperatures are above freezing.
Pruning – Thin broadleaf and narrowleaf evergreens when damaging low temperatures (below freezing) and drying winds are no longer a threat. Overgrown or unhealthy broadleaf evergreens may be rejuvenated to direct and control new growth. Shear formal hedges to maintain the desired shape, size and thick appearance.
Fertilizing – Fertilizer may be broadcast around ornamental landscape plants as the ground begins to thaw.
Watering – Irrigate newly planted, actively growing ornamentals any time there is less than 1 inch of weekly rainfall. Apply water at the rate of 1 quart per square foot of planting area on poorly drained soils. On well drained soils, use a half-gallon of water per square foot. Newly planted ornamentals not yet actively growing can be injured by overwatering.
Plant protection – For newly planted ornamentals, spread a 2- to 3-inch layer of mulch over the soil in the bed or around trees. Level winter mulch and use the excess to thicken thin spots in beds and around trees for a summer mulch to conserve moisture.
Source: Rebecca Finneran – MSU Extension & Bulletin E-1947