What is Organic Fertilizer?

We hear a lot about using organic products, but what exactly are they? When you visit the garden center, you often see the organic section of products with soils and compost, fertilizers, pesticides, and mulches. But say you want to pick up some organic fertilizer — what exactly is it, and what is in it? How is it different from a synthetic, or non-organic, fertilizer?

Beyond simply reaching for a fertilizer with the word “organic” on the label, here is some great information about what to look for as well as what you’re getting when you purchase.

What are organic fertilizers made of?

Organic fertilizers are made from mined rock minerals, and natural plant and animal materials. They include ingredients like manure, guano, dried and powdered blood, ground bone, crushed shells, finely pulverized fish, phosphate rock, and wood. While inorganic, or synthetic, fertilizers may contain some organic ingredients, the main difference is that they act quickly to simply feed the plant without actually enriching the soil, and may contribute to a toxic buildup of salts in the soil when overapplied.

What do I need to look for on the label?

Because some products include organic materials, the label will say “Made with organic materials” but may not be truly organic or natural. Frustrating, we know. To be sure you are buying a product that contains safe and natural ingredients, look for words like “slow release,” “natural organic,” and “low analysis.” Think twice about products that are labeled organic but have an N-P-K (nitrogen, phosphorus, potassium) ratio that adds up to more than 15.

What types of organic fertilizers are there?

Organic fertilizers can be powders, liquids, or solids, with each applied differently. Some organic fertilizers are manure or guano-based, using droppings from livestock, worms, bats, and seabirds. Bagged organic compost has a mixture of organic ingredients including manure, food scraps, and leaf mold. Look for other organic fertilizers including blood meal, bone meal, shellfish fertilizer, or fish emulsion.

How do I use organic fertilizers?

It depends upon the type you are using, so be sure to thoroughly read the package label and instructions. Some fertilizers also act as soil conditioners, and are applied to the soil before planting, while others are worked into the soil around the plants year-round. Still others are sprayed on the leaves of the plant as a foliar fertilizer. Each has its specific use and benefit.