If you ask ten professionals about fertilizer you are almost certain to get 10 different answers. The information below is what I have found to be effective generally throughout Zone 10 (Martin County south through The Keys.)
Commercial fertilizers are designed to make your lawn green and stimulate growth. It should be applied to achieve an objective/s: 1. Increase leaf and root growth, 2. Aid in recovery from foot traffic and pest damage, 3. Reduce and control weeds, and/or 4. Replace nutrients lost to leaching and transpiration. A soil test, often available at your county extension office will help determine the proper fertilizer to use. Based on the results the agent can recommend the best fertilizer to use.
All fertilizers have three bold numbers. The first number represents NITROGEN, the second PHOSPHORUS and the third represents POTASSIUM.
Nitrogen (N) for leaf development and vivid green color.
Phosphorus (P) for root growth and cellular function .
Potassium (K) sometimes called potash, for root development, improved winter hardness and disease resistance.
A label that reads (15-2-15) per hundred pounds contains: 15 Lbs. of Nitrogen, 2 Lbs. of Phosphorus and 15 Lbs. of Potassium (potash). The remaining weight consists of other nutrients, conditioners and fillers. Stay away from “Weed & Feed” products unless you have a uniform weed infestation. Spot treat weeds instead.
A good blend for South Florida lawns is 12-3-10 applied according to label directions in March, June and October.
Use product that is “Time-Release”, “Slow-Release” or “Controlled-Release”. Most good quality fertilizers are. The nutrients are encapsulated in spheres designed to release the contents as moisture hits the sphere over time. You will get a longer lasting response and the product will be safe to use, fewer nutrients are lost and less pollution is created. Measure your property and do the proper calculations to determine how much to use. Always follow label directions.
The University of Florida has for the last several years recommended the use of high quality PALM fertilizer as more than adequate for citrus in South Florida. Slow release 8-2-10 or 8-3-9 with micronutrients such as Magnesium, Manganese, Zinc, Iron, etc. Apply at the rate of 1/2 Lb. per foot of circumference of branch spread, starting one foot away from the trunk to just past the drip line. Apply like salt on a hamburger. Fertilize citrus every other month. Citrus trees also appreciate foliar nutrition spray as well. There are several to choose from on the market. When using these be sure to saturate the tree – top and bottom of all leaves. This spray will actually be absorbed by the leaves and trans-located throughout the tree. I spray our citrus trees with nutritional spray in March, May, July, September and November. Notice that the spraying alternates with my citrus fertilizer months of February, April, June, August and October. There is some disagreement among scientists: some say citrus do not absorb through their leaves, others disagree. I use nutritional spray on all our citrus anyway and I think it helps.