Improper lawn fertilization can negatively impact our environment, as well as our water quality. If we apply too much fertilizer, it can wash off our lawns and into our waterways -causing nuisance plants to grow, and harming fish and wildlife.

The best thing you can do to prevent pollution and maximize plant health is to follow Integrated Pest Management strategies and utilize Florida Friendly plant selection and landscape design standards.

• Integrated Pest Management addresses pest issues at the root causes, reducing the need for additional chemical inputs and continuous treatment UF|IFAS website

• Florida Friendly Landscaping encourages plant selection, landscape design, and gardening practices which keep in mind the Florida environment. Florida native plants are adapted to Florida soils and climate, requiring less irrigation and fertilizer than exotic ornamental plants UF|IFAS Florida Friendly Landscaping program

If you have to fertilize then fertilize appropriately to prevent pollution and maximize plant health by following University of Florida’s recommendations (download PDF): 

1. Apply fertilizer to your lawn only when grass is actively growing
2. Know your water source – reclaimed water may already contain nutrients like nitrogen, Soil Testing is an option to learn what nutrients your lawn or garden needs 
3. Choose slow release products with potassium and little to no phosphorus
4. Don’t get fertilizer on hard surfaces, if you spill clean it up – DO NOT RINSE EXCESS FERTILIZERS INTO STORM DRAINS
5. NEVER fertilize within 10ft of any water body
6. Don’t fertilize before a heavy rain
7. Avoid using “weed and feed” products
8. Understand and read the labels when selecting a fertilizer

Before you buy that bag of fertilizer, consider the following misconceptions:

Misconception: The higher the three numbers on the front of the bag, the better the fertilizer is for the lawn.

Reality: The three numbers on the front of each bag of fertilizer represent its nutrient concentration in percentile form. That means a bag of fertilizer labeled 20-5-25 contains 20% nitrogen, 5% phosphorus and 25% potassium. (The rest of the bag may contain some minor nutrients and filler material.)

Excessive nutrients have been shown to cause numerous water quality problems in our canals and ponds - problems that may ultimately find their way to the Everglades and ocean reefs. Since phosphorus is found naturally in South Florida soils, your lawn doesn't require additional amounts for growth. So select a bag of fertilizer with a middle number (its phosphorus concentration) of 2 or less and that is at least 50% slow release.

Misconception: I should fertilize my lawn once per month.

Reality: Lawns should be fertilized only as needed. Also, you should never apply fertilizer before a major rain event: the precipitation will wash the fertilizer past the root zone before the grass can absorb it. The most effective time to fertilize the lawn is prior to our rainy season - which runs from June to November. March is ideal for fertilization because it's the start of the growing season; October is also a good choice, as it allows for proper nutrition during our dry season.

In 2009, the Florida legislature recognized Best Management Practices (BMPs) for protection of water and made training mandatory for commercial fertilizer applicators. If you mow, prune, plant, weed, fertilize, water or take care of pest problems professionally then a good resource is the Best Management Practices for Protection of Water Resources by the Green Industries.

Resources:

• Best Management Practices for Protection of Water Resources by the Green Industries [download PDF].
• NatureScape Broward publications
• Natives For Your Neighborhood Plant List