What to do in the garden in May

The danger of frost is (mostly) past, and summer will be here by the end of the month.


Don’t fertilize cool-season turfgrass (fescue, bluegrass). It has been growing actively all winter, and it will begin to go dormant as summer heats up. Let it slow down naturally, and it’ll be better able to withstand the heat and drought of summer. 7 Aerify warm-season lawns (zoysia, bermudagrass, centipede) to loosen the soil and allow for better water and air infiltration. 16

Call for a Lawn Maintenance Calendar for your type of grass.


Prune spring-flowering shrubs after they bloom. The best time to prune azalea, rhododendron, forsythia, spirea, flowering quince, kerria, pieris, and weigela is just as the flowers begin to fade. Don’t wait till summer, or you’ll cut off next year’s flower buds. To keep your shrubs ever-young, prune one-third of the oldest canes back to the ground each year.

Prune wisteria frequently throughout the summer, to control vegetative growth and get better blooms next spring.

Watch crape myrtles for evidence of aphids. The sugary residue from aphids’ feeding is responsible for the black sooty mold often seen on crape myrtles later in the season. Control aphids with insecticidal soap, horticultural oil, or with more aggressive pesticides.

Keep dogwoods healthy. Two major disease problems show up on dogwood trees in late spring and summer. Spot anthracnose can be disfiguring, but our hot summers keep it from being a major problem. Powdery mildew can distort the leaves and reduce the tree’s ability to make sugars for growth. To help dogwoods overcome diseases: keep them watered, maintain soil fertility, and clean up leaf litter to reduce disease pressure.


Plant summer annuals and vegetable crops now that the soil is warm and the the danger of frost is past. Sow seeds of beans, squash, cucumbers, and corn. Set out transplants of tomatoes, peppers, eggplant and okra. Plant dahlias, caladiums, coleus, and all those colorful bedding plants.

Pinch your plants. Use your index finger and thumbnail to break out the lead growth at tips of branches. Pinched plants have shorter, sturdier stems, more lateral branching and more blooms. Pinch back mums, zinnia, salvia (red sage), cockscomb (celosia), petunias, marigolds, snapdragons, and garden phlox. Pinching also works well for many vegetable plants, including tomatoes and peppers.

Stake floppy plants, such as peonies, dahlias, and Boltonia (Michaelmas daisy), while they’re small, so they’ll have support when they need it. After plants have grown large, they can be injured by staking and tying.

Cut roses properly. Removing too much wood and foliage when cutting flowers can seriously weaken your rosebushes, especially during the first year. Leave 2-3 well-developed leaves (groups of five leaflets, not three) between the cut and the main stem.

Grow great bearded iris by giving them excellent drainage, fertile soil, sunshine, and beds free of competing weeds and grass. Divide frequently (in August) for larger and finer blooms.

Mulch! Prepare for dry summer weather and control weeds at the same time, by using a layer of mulch 2-3″ thick. Pine straw, wood chips, or pine bark make good mulch. 21 Banish bermudagrass (Wiregrass) from your planting beds. Keep it pulled to prevent it overrunning your garden. If weedy grass gets out of control in your flowerbeds, try using a selective herbicide that only kills grasses.


Welcome back hummingbirds! Females will be in the area first; the males will follow soon. Salvias, honeysuckles, penstemons, and other tube-shaped flowers, especially red ones, will attract hummingbirds to your garden. Fill feeders with a solution of 1 part sugar in 4 parts water. Wash feeders and replace the food at least twice a week.

Watch for slugs. These soft, slimy, slender animals seem to have a special taste for tender young crops in spring. Holes in leaves or on the leaf margins and a silvery slime trail in the morning indicate a slug feast the previous night. Slugs hide under boards, stones or debris during the day. Call for a bulletin on control of slugs.


Plant vegetables in your flower beds! Eggplant, pepper varieties, and cherry tomatoes make colorful additions to the garden. Bush beans and climbing beans have attractive foliage and charming small flowers. Vegetables can also mingle with flowers in pots on a patio or deck.

From: http://www.ces.ncsu.edu/durham/agriculturehorticulture/mg/gardencalendar/may.php