Right Fertilizer, Right Place
The third principle of Florida-Friendly Landscaping™ is “Fertilize Appropriately.” It's not always necessary to fertilize your plants or lawn. Plants have varying nutrient needs depending on the species, the age of the plant, and its location. A soil test can help you to understand what nutrients are present in your soil. This is an important step to help you decide what, if any, nutrients you should add. When looking for fertilizer, "weed and feed" products are not recommended for a Florida-Friendly landscape.
"Weed and feed" products contain fertilizer combined with weed killers (pre-emergent herbicides). While it may seem like a time-saver to apply these products at once, the truth is they are more likely to hurt your landscape than help.
"Weed and feed" products often leave one or both of the products less effective. This is because the appropriate timing is often different for pre-emergent herbicides and fertilizers. Generally, pre-emergent herbicides should be applied much earlier in the year than is appropriate to apply fertilizers. Applying either, or both, of these products at the wrong time of year makes them less effective.
Additionally, "weed and feed" products can injure some trees and shrubs. Their root systems can extend far beyond the canopy drip line, where they intermingle with turf and absorb the herbicide from the "weed and feed" product.
A fact especially important for Florida homeowners is that the pre-emergent herbicides contained in these prodcuts can actually harm lawns if applied when temperatures are above 90°F for three consecutive days. This phototoxic effect can cause a lot of harm to a lawn that was healthy to begin with.
As always, it is important to completely read the entire packaging label before using any product. And be sure to follow the latest UF/IFAS recommendations regarding ideal application rates, timings, and formulas, which will be different for different plants. Herbicides and pesticides should only be applied to affected areas, not broadcast over the entire yard—as is done with "weed and feed" products.
So remember, while at first glance it may seem like a time-saver, using "weed and feed" on your Florida lawn is likely to cost you in the long run. The key to selecting a fertilizer is understanding what nutrients your plants need. Before you fertilize, contact your local UF/IFAS Extension office to get a soil test and refer to the document General Recommendations for Fertilization of Turfgrasses on Florida Soils.
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Special thanks to the staff of the UF/IFAS Florida-Friendly Landscaping program for their expertise and assistance on this article.