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Oklahoma Gardening

Garden Tips for May


  • Cool-season lawn can be fertilized again. If you did not fertilize cool-season grasses in March and April, do so now. This should be the last application until fall.
  • Warm-season lawns may be fertilized again in May.
  • Seeding of warm-season grasses such bermudergrass, buffalograsses, zoysiagrass and centipedegreass is best performed in mid-May through the end of June.
  • Vegetative establishment of warm-season grasses can continue.
  • Nutsedge plants become visible during this month. Apply post-emergent treatment 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.


Fruits and Vegetables

  • Pant 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.


Water Gardens

  • Clean out water garden and prepare for season. Divide and repot water garden plants.
  • Begin feeding fish when water temperatures average 50°F.



  • 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.


Trees and Shrubs

  • Prune and feed azaleas immediately after blooming.
  • Insect Alert:
    • Bagworms on juniper and arborvitae. (Late May)
    • Elm leaf beetles and larvae on elms. (Late May)
    • Lace bugs on sycamore, pyracantha and azalea.
    • Soak new transplants unless rainfall is abundant.
    • Pine needle disease treatments are needed in mid-May.