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September Gardening Tips

David Hillock, Consumer Horticulturist

Oklahoma Cooperative Extension Service

Division Of Agricultural Sciences and Natural Resources

  • Vegetables

    You have all of September to plant cool-season vegetables like spinach, leaf lettuce, mustard and radishes, and until the middle of September to plant rutabagas, Swiss chard, garlic and turnips.

  • Flowers

    Plant cool-season annuals like pansies, ornamental cabbage or kale, snapdragons and dusty miller when temperatures begin to cool.


    Choose spring flowering bulbs as soon as available.

  • Landscape

    Watch for fall specials at garden centers and nurseries since fall is a great time for planting many ornamentals.


    Choose spring flowering bulbs as soon as available.


    Watch for and control any late infestations of tree webworms.


    Twig girdler insects should be controlled if large numbers of small branches of elms, pecans or persimmons are uniformly girdled from the tree and fall to the ground.


    Begin to reduce the amount of light on outside tropical houseplants by placing them under shade trees before bringing them indoors for the winter.

  • Lawn and Turf

    Last nitrogen fertilizer application of the year on warm-season grasses should be applied no later than September 15. (Printable: HLA-6420)


    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 second week of September.  Note: Do not treat areas that will be seeded in the fall.


    Continue bermudagrass spray program with glyphosate products for areas being converted over to tall fescue this 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 (Printable: HLA-6419).


    White grub damage can become visible this month. Apply appropriate soil insecticide if white grubs are a problem (Printable: EPP-7306). Water product into soil.

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