It’s best to mix compost with mineral soils (clay, sand or loam) for gardening. Combining mineral soils and compost creates ideal texture and provides anchorage for plant roots. To start gardening, mix 1/3 compost (by volume) with 2/3 clean fill, or with the soil in your yard. Then each year add about one inch of compost to the garden, and dig it into the soil in spring or fall.