Weed-and-feed products sound like ideal solutions to many homeowners because they tackle two problems at one time. Weed-and-feed fertilizers generally contain nitrogen (feed) and a pre-emergent herbicide (weed) and carry several considerations for Florida lawns.
According to the University of Florida's IFAS Extension Service, around February 15 is the correct application date for pre-emergent herbicides. More specifically, it is around the time that daytime temperatures remain at 65 to 70 degrees Fahrenheit for four or five days a week.
Florida lawns have various turf types. Different turf grasses require different herbicides for the "weed" part of a weed-and-feed. Using the wrong one might damage your turf grass.
While February 15 is the general date for applying pre-emergent herbicides, it is also still during the winter. The nitrogen in the weed-and-feed can accelerate and promote new grass growth, which it should, but a possible cold weather burst after this date can damage and possibly kill the young grass.
Apply slow-release granular fertilizer two or three times per year at a rate of 1 lb. of nitrogen per 1,000 square feet of grass. Keeping a healthy lawn through proper fertilization, mowing techniques and watering will help to prevent weeds, thus eliminating the need for the pre-emergent herbicide.