Although temperatures are still hovering around 90° F, the last fall fertilization date is approaching quickly. Mid-September is the
deadline for applying fertilizer to warm season turf-grasses and landscape ornamental plants for the year. Why is September 15 the cutoff date? In North Florida, our estimated first frost date is November 15. When fertilizer is applied the nutrients encourage new growth that typically takes about 6-8 weeks to become “hardened off” and able to tolerate low or freezing temperatures. So, simply backtracking on the calendar gives you an idea of when to make the last application of fertilizer (if needed).
If September 15 is at the end of our warm season feeding schedule, the next question should be “when should I fertilize in the spring?” Although Northwest Florida’s average last frost date is listed as March 15, UF/IFAS Turf Specialist Dr. Bryan Unruh does not recommend fertilizing before April 15 in the panhandle. There are two main reasons for this later date. One is that the March 15 last frost date is an estimate, many times cold weather follows a warming trend in late winter/early spring. During April of this year warm weather was followed by cool temperatures with cold winds that caused landscape plant damage. If fertilizer was applied before this weather arrived, some cold damage may have been evident this spring in affected landscapes. The second reason is that if fertilizer is applied to turf or plants that are not actively growing and using those nutrients, it may leach out of our sandy soils. Nutrients do not wait for plants to use them; they can be washed out and become a source of nonpoint source pollution.
To read more tips on fertilizing visit EDIS ENH1174 “The Lawn Fertilizer Toolbox”