Grady Miller, Professor and Extension Specialist
Fall is the best time for renovation and seeding of cool-season lawns. In a normal year, we expect an increased chance for rainfall and cooler temperatures within the first few weeks in September. This makes an ideal time for fall renovation. With the long duration of hot and dry weather this summer, this is a year that many cool-season lawns will need renovation to get them back in shape before Thanksgiving.
Optimum air temperatures for tall fescue germination are 68 to 77°F and soil temperatures greater than 60°F. If tall fescue is seeded in less than ideal conditions (too cool or no soil moisture),the results may be a thin turf stand going into the winter. So, it may be better to seed a little early than waiting and seeding too late.
It is best to choose cultivars from the turffiles website (http://turffiles.ncsu.edu). If you buy a tall fescue blend, try to find one with at least one of the cultivars from the list of recommended cultivars. These grasses were chosen because they produce a high quality turf in North Carolina and have been shown to be less susceptible to brown patch. Some like to mix in a little Kentucky bluegrass (darker color and finer texture) or fine fescue (for shady areas). Do NOT add ryegrass to the mix. A typical tall fescue seeding rate is 5 to 6 pounds of seed per 1000 square feet. Germination will normally be in 10 to 21 days with soil moisture and suitable soil temperatures.
Before seeding core aerification is recommended to reduce soil compaction. Decent soil moisture from a good soaking rain or from a thorough irrigation is needed for good core cultivation tine penetration. Getting good soil to seed contact is paramount to maximize available soil moisture. The core aerification holes will capture seed and hold moisture so the tall fescue seedlings often come up as a tuft of turf from the aerification holes.
Follow normal tall fescue fertilization practices as outlined in Carolina Lawns available to download on the www.turffiles.ncsu.edu website. The suggested nitrogen application is about 1.0 pound of nitrogen fertilizer per 1000 square at seeding. Include phosphorus and potassium fertilizers if soil tests indicate there is a need. In the absence of a soil test, a 16-4-8 or similar N-P-K ratio fertilizer may be used. Before additional fertilizer and lime are added, conduct a soil test (http://www.ncagr.com/agronomi/sthome.htm).
To apply 1 pound of nitrogen per 1,000 square feet: Divide 100 by the first number on the fertilizer bag to determine the amount of product to be used per 1,000 square feet. Example: Using a 16-4-8 fertilizer, 100 divided by 16 equals 6.25, therefore, 6.25 pounds of fertilizer per 1,000 square feet will deliver 1 pound of nitrogen.
If irrigation is available, set your controller within current water restrictions for your area. Irrigate early in the morning to reduce water loss due to evaporation. In the fall, ¼ to ½ inch water per week of water (via rainfall or irrigation) is generally sufficient to meet the turf’s water needs. To dial in your irrigation settings based on turfgrass needs for your location, use the TIMS website available at http://www.turffiles.ncsu.edu/tims.
Since seeds and seedlings may be damaged by some herbicide applications, fall seeded tall fescue should not have any herbicides applied until it is extensively tillered. Heavy weed populations should be controlled prior to seeding (see Turf Alert: Crabgrass control prior to fall-seeding tall fescue)
It is very important that tall fescue be maintained at the proper mowing height to allow it to mature before winter and to minimize weed incidence. Studies have shown that a 3½ mowing height provides the best growth condition while minimizing disease incidence and weed encroachment.
Note that warm-season grasses such as bermudagrass, zoysiagrass, centipedegrass, and St. Augustinegrass can be sodded in the fall, but it is generally not recommended due to the increased chance of winterkill. Warm-season grasses should not be seeded in the fall as there is inadequate time for maturity before the first expected frost.