Northern & Central Midwest
Allow Bulb Foliage to Wither
Be sure to let bulb foliage yellow before removing it. These leaves continue to photosynthesize, providing food for the bulb, and removing them before they wither may strain the bulb and reduce its flowering capacity. Yellowing foliage can be hidden by planting other perennials, ground covers, or annual flowers.
Plant Tropical Water Lilies
Tropical water lilies should be held indoors until the temperature outdoors remains at 65 degrees. Repot them before putting them out if their pots are filled with roots. Begin fertilizing as soon as they begin to grow, and expect flowers about a month after the first leaves.
Don't Forget Summer Bulbs
As spring bulbs begin to fade, look for summer bulbs to replace the color. It's time to plant summer- and fall-blooming bulbs, such as Asiatic and Oriental lilies, dahlias, peacock orchids, cannas, tuberous begonias, caladiums, crocosmia, gladiolus, montbretia, and calla lilies. The tender bulbs grow well in containers and can easily be brought indoors in fall.
Prune Flowering Shrubs
Prune spring-blooming shrubs and trees as soon as they finish their display. Forsythia, viburnum, lilac, spirea, flowering almond, serviceberry, and crab apple all benefit from light, rejuvenating pruning. This also is the time to prune out old forsythia and lilac stems. Cut them as close to ground level as possible.
Fertilize Your Lawn
Mid-May is a good time to feed your lawn. Figure out the amount of fertilizer your lawn needs for the year and give it one half now and then the other half in the fall. If you have weed problems, this is the time to pull or spot treat. Also, keep weeds mowed to prevent seeding.