Types of Fertilizer

There are many options for how you convey nutrients to your plants. Many gardeners use a combination of different fertilizers and techniques. Try using granular products or manures to supply the main nutrients and liquids to correct minor deficiencies or quickly boost growth. The key to selecting a fertilizer is understanding what nutrients your plants need.

Slow- and Controlled-Release Fertilizers

Slow- and controlled-release fertilizers provide nutrients to plant roots over an extended period of time. This allows you to fertilize less frequently—and to prevent nutrients from leaving your landscape and entering waterways, contributing to harmful algal blooms and other water quality problems.

In Florida, any fertilizer that is labeled "slow-release" or "controlled-release" must contain 15 percent or more slow- or controlled-release nitrogen. The label will indicate the percentage of slow- or controlled-release nutrients in the fertilizer, and it's best to choose a fertilizer with higher amounts of slow-release nitrogen.

For the vegetable garden, it's a good idea to add quick-release fertilizer and a slow-release source to the soil at planting so that your plants have nutrients readily available to them when they're young, and then gradually receive the nutrients they need as they grow.

Inorganic Fertilizers

Inorganic fertilizers are materials that are mined or synthesized from non-living materials. Many inorganic fertilizers contain nutrients that are immediately available to plants. Others are formulated to allow nutrients to be released over a period of time. If you use an inorganic fertilizer in your landscape, choose one with some or all of the nutrients in slow- or controlled-release form, so that the plants will be able to take up the fertilizer as it is gradually released.

Organic Fertilizers

Organic fertilizers are materials that are derived from plants and animals; one of the most common forms is manure. Organic matter incorporated into the soil before planting will help fertilize your vegetable plants, but you'll need to add additional fertilizer after planting. Composted animal manures used in place of inorganic fertilizer are best applied as a side dressing—this means they're placed next to rows.

The quick availability of nutrients, especially nitrogen, is very important in vegetable growing. Therefore, you may want to supplement any organic fertilizer you apply with some inorganic fertilizer for quick feeding. Many gardeners use a combination of fertilizers and techniques in the garden.

Gardeners who wish to avoid chemical fertilizers can also use fish emulsions or manure teas. Fish emulsion, which is usually high in nitrogen but low in phosphorus, is mixed with water and sprinkled around plants every two to three weeks, or as needed. It typically has a 5-1-1 analysis.

Manure tea is made by seeping manure in a barrel or tub of water. Place several shovelfuls of manure in a porous cloth sack, then soak the sack of manure in the water until the water becomes the color of weak tea.

Read "Organic Matter" to learn more about this subject.

Dry Fertilizer

Dry fertilizer can be applied in many ways. Scatter it over the entire garden, down a row, or ring individual plants. You can broadcast dry fertilizer (1 pound for each 100 square feet of garden or 100 feet of row) over the entire garden plot before planting. Then after planting, side-dress along the plant rows. The fertilizer should be applied 2–3 inches to the side of, and 1–2 inches below, the seed level or plant row. Avoid applying fertilizer when foliage is wet, and water after applying it to remove particles from foliage. For best results, use small amounts or light concentrations of fertilizer, and spread it over the root zone.

Water-soluble Fertilizer

Water-soluble fertilizers are often useful as a quick boost for vegetables. Liquids or crystals mixed with water are applied as frequently as once a week. The nutrients, easily distributed by a gardener with a sprinkling can, are readily available to plants. These fertilizers are especially handy for container-grown plants.

Foliar feeding, a technique of spraying plants with dilute liquid fertilizer, is rarely part of regular maintenance. Instead, use it to provide a special boost or to supplement micronutrients like iron, manganese, or zinc.

Read "Fertilizing the Vegetable Garden" to learn more about this subject.