Soil Amendments and Nutrients: A Complete Guide to Improving Garden Soil

All gardens benefit from regular soil amendments. Apply individually or in combination each season and at planting. Spread compost, manure, and peat 3 inches deep and work into the top 3–6 inches. Apply ½ inch or less of sand, greensand, vermiculite, perlite, or gypsum, working into the top 8 inches. Continue reading

Common Soil Amendments

Compost

Decomposed leaves, grass clippings, and kitchen scraps. A balanced, slow-release, humus-rich amendment that lightens heavy soils and enriches poor ones. Learn to make your own compost.

Sand

Coarse sand improves drainage and loosens clay in small amounts. Too much creates concrete-like soil. No nutrients, but lasts indefinitely.

Manure

Aged or rotted manure boosts nitrogen, loosens heavy soil, and improves water retention in light soils. Fresh manure burns plants; compost for a year first.

Peat

Absorbs moisture, helps sandy soil, loosens clay. Can become crusty if dried out. Peat bogs are fragile; use sphagnum peat moss instead.

Vermiculite

Heated mica that holds moisture and loosens soil. Good for all soil types; lasts indefinitely.

Perlite

White volcanic residue that aerates soil indefinitely. Good for all soils; a little goes a long way.

Greensand

Powdered rock with potassium and other nutrients. Slows compaction and retains moisture.

Gypsum

Powdered mineral that loosens heavy clay and improves drainage.

Use our mulch calculator to determine how much you need.

Basic Nutrients (N-P-K)

Plants need nitrogen (leaf/stem growth), phosphorus (roots, flowers, disease resistance), and potassium (fruit/seed). Organic sources:

Nitrogen Sources

• Alfalfa meal
• Blood meal
• Composted manure
• Cottonseed meal
• Feather meal
• Fish meal/emulsion
• Mushroom compost
• Rice hulls

Phosphorus Sources

• Bat guano
• Bonemeal
• Rock phosphate

Potassium Sources

• Dolomite lime
• Greensand
• Kelp meal
• Oyster-shell lime
• Rock dust
• Seaweed
• Wood ashes

Tips for Better Soil