The Basics of Fertilizer

Plants and grasses need nutrients to grow and typically get them from the soil. But sometimes we apply fertilizer to help them along. Fertilizer provides specific nutrients for your plants, and it’s available in a variety of forms. Inorganic fertilizers are mined or synthesized, while organic fertilizers are derived from living organisms.

Different plants have different nutrient requirements, and in many cases a fertilizer product may not be necessary, so know your plants’ needs and do your homework before you purchase and apply fertilizers.Your landscape plants may need a different fertilizer than your turfgrass. Sometimes, specific plants, like azaleas or palms, need a special formulation of fertilizer.

Consider having your soil tested to see what’s present and what’s lacking. Kits are available at your county Extension office.

Plants also benefit from the right amount of fertilizer. With container-grown plants, applying too much fertilizer can create a build-up of salts in the potting media, which can cause stunted growth, leaf browning, or even death. And in the landscape, overfertilizing can burn plants, trigger excessive growth, aggravate pest problems, or lead to pollution of our waterways and groundwater.

For your lawn and landscape, use slow-release products that require fewer applications and may be less likely to leach nutrients into the water supply. Before you apply any fertilizer, make sure you read and understand the label, and that you follow all label instructions.

Understanding Fertilizer Labels

The label includes a series of numbers that indicate the percentage of nitrogen, phosphorous, and potassium, by weight. For example, a 16-2-8 fertilizer contains 16 percent nitrogen, 2 percent phosphorous, and 8 percent potassium. Be sure to purchase a fertilizer with 2% phosphorus or less in accordance with Florida State Law. The exception to this would be when fertilizing edibles; they may need more phosphorus.  A soil test will help you determine that.

The label also lists all of the other nutrients as part of the guaranteed analysis, and information about how to properly apply the product. The fertilizer label specifies if the fertilizer is water soluble or controlled release, indicating if the nutrients will be available immediately to plants or slowly over time.

Remember that you should apply only as much fertilizer as plants can use, and always fertilize responsibly. Learn more in the EDIS publication, “The Florida Fertilizer Label.”

Using a Spreader

Dry fertilizers can be applied with either a drop or a rotary spreader. A drop spreader creates a tight pattern, but you must be careful that each pass meets exactly with the previous one to avoid gaps.

The rotary spreader usually has a wider pattern of distribution, can cover a larger area in a short time, and there’s less chance of missed areas. But it can scatter granules where they shouldn’t be, like on hard surfaces like sidewalks or in bodies of water.