David Hillock, Senior Extension Specialist
Trees and Shrubs Prune and feed azaleas immediately after blooming. Insect Alert: (EPP-7306) Bagworms on juniper and arborvitae. (Late May) Elm leaf beetles and larvae on elms. (Late May) Mimosa webworms on mimosa and honeylocust.
Lace bugs on sycamore, pyracantha, and azalea.
Soak new transplants and newly planted trees unless rainfall is abundant.
Pine needle disease treatments are needed in mid-May. Turfgrass
Cool-season lawns can be fertilized again. If you did not fertilize cool-season grasses in March and April, do so now.
Warm-season lawns may be fertilized again in May. (HLA-6420) The seeding of warm-season grasses such as bermudagrass, buffalograss, zoysiagrass and centipedegrass is best performed in mid-May through the end of June. The soil temperatures are warm enough for germination and adequate growing season is present to promote winter hardiness.
Dollar spot disease of lawns can first become visible in mid-May. Make certain fertilizer applications have been adequate before ever applying a fungicide. (EPP-7658) Nutsedge plants become visible during this month. Post-emergent treatments are best applied for the first time this month. Make certain warm-season grasses have completed green-up.
The second application of pre-emergent annual grass herbicides can be applied in late-May or early June, depending upon timing of first application. Check label for details.
Vegetative establishment of warm-season grasses can continue. (HLA-6419) Flowers
Annual bedding plants can be set out for summer color.
Plant summer bulbs such as cannas, dahlias, elephant ear, caladiums, and gladiolus.
Shake a leaf over white paper to look for spider mites. If the tiny specks begin to crawl, mites are present.
Water Gardens
Clean out the water garden and prepare for season. Divide and repot water garden plants.
Begin feeding fish when water temperatures are over 50°F.
Fruits and Vegetables
Plant watermelon, cantaloupe, cucumber, eggplant, okra, sweet potatoes, etc.
Fruit spray programs should be faithfully continued during the next several weeks.
Late May is the best time to control borers in the orchard. Check for label recommendations and controls.