What to Look For

An organic lawn or garden starts with healthy soil. Natural fertilizers promote the growth of beneficial bacteria, earthworms and fungi that build soil structure and foster healthy plants.

The best fertilizer for your lawn and garden is homemade compost, made from food scraps, lawn clippings and fall leaves. If you still need store-bought products, here are a few tips.

Compost: Commercially made compost has high levels of naturally occurring phosphorous and nitrogen that is released gradually and is absorbed more easily by plants. Other soil improvers, such as worm castings, Epsom salts and decomposed organic matter called humates, add nitrogen, phosphorus and potassium. Watch out for commercial fertilizers, even those labeled "organic," that contain harmful ingredients, such as animal byproducts or sewage sludge. Animal byproducts, such as bone meal or fish meal, may have come from industrial farming operations, and sewage sludge, could be contaminated with diseases or heavy metals.

"NOFA Approved" and "OMRI Listed": The Organic Materials Review Institute (OMRI) and the Northeast Organic Farming Association (NOFA), an accredited certifying agency for the USDA National Organic Program, approve products that have been composted according to USDA Organic standards. The only synthetic materials that can be added to NOFA approved compost are those allowed in organic crop production.

Shopping Tips

• Have your soil tested by your local USDA Cooperative Extension Service to determine pH and what nutrients, if any, your grass is missing, or test it yourself with a soil testing kit.

• Once you know the pH, you can add organic matter to help balance it. Lawns prefer slightly acidic soils with a pH range of 6.5 to 7, but flowers, shrubs and trees vary in their pH preferences. Lime helps balance acidic soil, while sulfur helps with alkaline.

• To find out the nutrient content of a fertilizer, look for the "NPK" number (NPK stands for nitrogen, phosphorus and potassium). A "5-6-5" NPK number, for instance, means that a fertilizer is 5 percent nitrogen, 6 percent phosphorus and 5 percent potassium with the remaining 84 percent representing filler material.

Usage Tips

• Only spread about 1/2 an inch of compost on your lawn at a time. Even though plant-based nitrogen is more easily absorbed, composts and organic fertilizers can still be applied too heavily, leading to nitrogen- and phosphate-heavy runoff.

• Avoid applying fertilizer before a downpour that will rinse it away before it gets absorbed.

• Wear a mask if you're applying dusty fertilizers made with lime or any other fine particles you might inhale.