GREEN COVE SPRINGS – If you follow news related to the waterways of Florida, the Chesapeake Bay in Maryland, or in many other areas of our country, you are likely aware of the water quality issues that can arise from too much fertilizer.

When applied in excess, this resource necessary for the growth of many of our agricultural products and landscapes, is not utilized by plants and makes its way down into groundwater or washes over the surface into nearby waterways, either directly or down a street a storm drain until it reaches water. These nutrients can allow algae to grow heavily in the waterways, lowering the dissolved oxygen and light transmittance or can create disease issues. Extra fertilizer can even lead to further issues in your lawn and landscape.

This raises the question: How do you know when it is time to fertilize? Luckily, the University of Florida has tips from the Florida-Friendly Landscaping program which can help you protect the environment.

Know your fertilizer

Fertilizers often contain a blend of nutrients that are needed for plant growth with most mainly consisting of Nitrogen, Phophorous and Potassium. These nutrients are listed on the label of fertilizer products as percentages of the total product. For example, a fertilizer with an analysis of 8-0-16 would be 8 percent Nitrogen, 0 percent Phosphorous and 16 percent Potassium. The remainder of the product is made up of inert materials or other nutrients also needed for plant growth such as Iron, Magnesium, and Calcium. Your first two numbers, Nitrogen and Phosphorous, often cause the most problems with water pollution.

When choosing a fertilizer, choose one that will work for the plant and purpose and has slow release nutrients, which will break down over time and provide nutrition at a more balanced pace. Also, utilize little phosphorous unless needed and never use “Weed and Feed” products.

Organic fertilizers, such as composts, can also be utilized in the landscape as a soil amendment to provide slow release nutrients. These will usually be lower in nutrient levels than many commercially available products but can lessen the need for inorganic products and are usually low in phosphorous.

Know your plants and property

Just like animals need different diets, each type of plant usually requires different amounts of nutrients for optimum growth. For example, your St. Augustine grass lawn will use much more Nitrogen fertilizer than if you have Bahiagrass. Use UF/IFAS recommendations based on the plant you are providing fertilizer for and it will grow well without the danger of applying excess nutrients.

It is also helpful to know your property as some areas of the county will show different levels of nutrients already present based on the prior usage of the land and the properties of the soil. Some areas of the county need supplemental nutrition every year while others may have enough of many nutrients to survive. Get a soil test, such as those offered by the University of Florida, to determine what needs to be applied.

Know how to apply

When applying fertilizer, wait until April in our area for your lawn as you never want to apply it while the grass and plants are not growing. After application, water in with a maximum of ¼-inch of water. Also, never fertilize before a heavy rain or within 10 feet of any water body. Keep fertilizer off of any impervious surfaces and if spilled, clean up what you can. If we all do what we can, the risk of environmental damage can be lessened and our landscapes can still be lush and beautiful.

If you have any questions about fertilizer, the Master Gardener program, landscape and garden topics, or need plant or pest materials identified, contact the University of Florida/IFAS Extension Office online at http://www.clay.ifas.ufl.edu, follow us on Facebook, or call by phone at (904) 284-6355.