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Oklahoma Gardening

Garden Tips for September

David Hillock

Landscape & General

  • Seal up the house to keep out insects seeking shelter for the winter.
  • Watch for fall specials at garden centers and nurseries since the fall is a great time to plant many ornamentals.
  • Plant cool season annuals toward the latter part of the month.
  • Prepare tropical houseplants that have been outdoors for the summer to return indoors by placing them in shaded areas so they can adjust to the lower light levels.



  • Cool season crops like lettuce, radishes, rutabagas, spinach, etc. can be established during September for a fall crop.



  • Early September is the last opportunity to fertilize warm season grasses. Don’t apply fertilizer much past the middle of the month.
  • Winter broadleaf weeds like dandelion will begin to emerge in late September, which is also the best time to control them with a 2, 4-D type herbicide.
  • If pre-emergent control of winter-annual weeds (henbit, chickweed, annual bluegrass, etc.) is desired in lawns, the application should be completed by the 2nd week of September. (HLA-6421) Note: Do not treat areas that will be seeded in the fall.
  • Plan to seed bluegrass, fescue, or ryegrass as needed in shady areas in mid- to late-September. Fall is the best time to establish cool-season lawns (HLA-6419).