September gardening to do list

Much of the September list of garden tasks is taken from the OSU Extension Publication, HLA-6408—Landscape Maintenance Schedule with additional information added. This maintenance schedule is a checklist which emphasizes prevention rather than remediation. Some of the topics mentioned below have individual fact sheets which are available at


The last nitrogen fertilizer application of the year on warm-season grasses should be applied no later than Sept. 15. Applying nitrogen fertilizer after September can lead to lush fall growth that may cause the lawn not to be ready for cold weather and also makes the lawn more susceptible to the fungus that causes Spring Dead Spot disease. (HLA-6420)

Brown patch disease of tall fescue can still be a problem. (HLA-6420)

White grub damage can become visible this month. Apply appropriate soil insecticide if white grubs are a problem. Water product into soil. (EP7306)

Continue bermudagrass spray program with glyphosate products for areas being converted to tall fescue this fall. (HLA-6421)

Meet water requirements of turf. (HLA 6420)

If pre-emergent control of winter-annual weeds is desired in lawns, the application should be completed by the 2nd week of September. Note: Do not treat areas that will be seeded in the fall. (HLA-6421)

Plan to seed bluegrass, fescue or ryegrass as needed in the shady areas in late-September through mid-October. Fall is the best time to establish cool-season lawns. (HLA-6419)

Mow warm-season grasses at 2 1/2 inches and cool season grasses at 3 inches. No more than one-third of the grass height should be removed per mowing.

Trees and shrubs

Young trees and shrubs should be fertilized in both the spring and fall. If only one fertilization is given do it in the fall after the killing frost.


Choose spring flowering bulbs as soon as available.


Make or review your plan for a fall vegetable garden.

Plant garlic for next year’s harvest.

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