The next time you crack a few eggs to make breakfast or a baked good, don't toss away the shells. If you garden, the nutrients found in eggshells provide a decent and inexpensive source of fertilizer for your plants. Unlike synthetic fertilizers, when you use eggshells in your garden, you do not have to worry about going overboard. Keep in mind that eggshells alone won't provide adequate nutrition for plants.

Nutritional Analysis

Eggshells are primarily made out of calcium carbonate, which is the ingredient found in agricultural lime, according to the Master Gardeners of Hamilton County, Tenn. Jeff Gillman, author of "The Truth About Garden Remedies," did his own small test to determine the nutritional properties of eggshells. He steeped a shell in water for 24 hours and then sent the water to the lab. The lab results found that the eggshell-infused water contained 4 mg of calcium and potassium, as well as very small amounts of phosphorus, magnesium and sodium.

Steeping Shells

Make an eggshell fertilizer tea to use in your garden. Boil a gallon of water, and then add 10 clean and dry eggshells to it. For a stronger brew, add the shells of up to 20 eggs. Let the shells sit in the water overnight, and then strain the water. Pour the concentrate directly onto the soil to give plants a boost of calcium and potassium. Gillman recommends doing this once a week, though how often you have eggshells depends on your family's egg-eating habits.

Crushing Shells

Instead of making a tea, you can crush eggshells and add them directly to the soil in your garden. Collect shells throughout the winter so that you have an adequate supply at planting time. Wash and dry the shells to remove any egg residue. Place the shells into a food processor and process until a powder forms. Wear a dust mask when crushing the eggshells so that you don't breathe in the eggshell dust. Stir the powdered shells into the soil or potting mix just before planting. Gillman suggests using five shells per plant. You can also sprinkle a handful of shells into the planting hole before you set a plant root ball in it.

Benefits