The times to fertilize are March, June and September. Use Lesco Palm fertilizer 8-2-12 +4 (minor minerals that are essential) It has been formulated for our soil and the grass responds beautifully. it can be used on flowers and shrubs as well. Don't fertilize now. The dead patches you are seeing are maybe what is called "Large Patch" also called Brown patch, a fungus that stays in the soil and cannot be eliminated, only controlled. The cause of it are warm days and cool nights and wet shady conditions. If you have a lawn service, ask them to come and look at it because you think it has Large patch. One of the ear marks is a pale yellow halo around the dead area. Here are the key steps to treating Brown Patch:
- Water only in the morning
- Try to reduce watering as much as possible until the disease is gone
- Aerate the soil in the affected areas
- Aerate the entire lawn to stop further outbreaks
- Stop fertilization until the lawn is recovered
- Apply a fungicide if necessary
- Wash lawn mowers of all clippings after mowing an infected lawn
A good source for lawn and garden questions is University of FLorida. Check out what they have to say:
Lawn Diseases - Gardening Solutions - University of Florida, Institute of Food and Agricultural Sciences