Fertilizer and pesticides from our lawns

Algal Bloom on the St. Johns River

Nitrogen pollution comes from many sources, including from the fertilizers used on lawns and in landscaping. This nitrate-rich water makes its way to surface waters as runoff during rainfall or over-irrigation, or it may drain slowly from the soil over time.

Algal blooms in the lower St. Johns River near Jacksonville grow more in response to nitrogen pollution.

When fertilizing, using the correct amount of fertilizer can reduce the amount of pollutants reaching waterways, save water and your money, and result in a healthier landscape. Overfertilizing can aggravate pest problems, stimulate excessive plant growth, and demand frequent irrigation.

Fertilizers should be used only when specific nutrient deficiency symptoms are evident.

Florida-friendly lawns require only moderate amounts of supplemental fertilizer once they are established.

Tips

  • Avoid overuse of fertilizers, especially near the water’s edge. Rain and lawn watering can wash excess fertilizer into water bodies, where excess nutrients cause algal blooms and undesirable weed growth.
  • The amount of fertilizer to apply depends on a number of factors, such as grass species, soil type and permeability, and your location in the state. Apply fertilizers sparingly, and follow the manufacturer’s directions on the bag, particularly in terms of the amount per application. Know exactly how much area (square feet) of your lawn the bag of fertilizer is intended to cover.
  • Florida soil is naturally high in phosphorus, and therefore, a “No Phosphate” fertilizer is fine for most mature lawns. Apply a phosphate fertilizer only if lacking. For specifics to your area, contact the local County Cooperative Extension Service.
  • The best fertilizers for healthy landscapes and the environment are those that contain a high percentage of slow-release, water-insoluble forms of nitrogen. Water-insoluble products are not washed away like liquid or fast-release fertilizers. Slow-release products stay in the soil to supply nutrients to plants on a gradual basis, over a longer period of time. The product label will say organic, slow-release or controlled release, water-insoluble nitrogen, sulfur-coated, IBDU (15N-isobutylidene divrea), or resin-coated.
  • Fertilize only during the growing season, which can vary depending on where you live in Florida. Allow a month between autumn application and the first freezing temperatures, which will make new growth less vulnerable to frost.
  • Use pesticides, herbicides and fungicides only when needed, and apply them responsibly, following the label’s directions. Apply only on affected areas. Consider organic or nontoxic solutions.