What Is the Right Mixture for Topsoil Compost & Peat Moss?

Sandy Soil

• Sandy soil drains quickly. Nutrients get washed away because water moves so quickly through the soil. Add equal parts of compost and peat moss to sandy soil. This adds needed nutrients and helps retain moisture in the soil. Add topsoil only if soil erosion has been a problem and the top layer of soil has washed away. The mixture should be three-quarters compost and peat and one-quarter topsoil.

Clay Soil

• Clay soils drain poorly because the soil molecules are close together. Water puddles and can cause root damage. Adding compost to clay soils helps with drainage because the organic material opens up space between the clay molecules. Do not use peat moss with clay soils. It adds to the moisture retention problem and takes too long to decompose. Topsoil can be added if the original topsoil layer was removed during home construction. The mixture should be two-thirds compost and one-third topsoil.

Silt Soil

• Silt soil has less pore space than sandy soil and more than clay soil. It is the ideal soil in terms of drainage. Silt soil would only need composting to provide nutrients.

Raised Garden Beds

• Raised bed gardens are built on top of the ground. The gardener can build the soil from scratch. Mixing topsoil, compost, peat moss and vermiculite in equal parts will provide a rich fertile soil for growing plants. Vermiculite is made from rock and is added to keep the soil mixture from compacting.