Assessing Garden Soil

The garden soil in which your plants grow serves four basic purposes. It helps, through its structure, to hold the plant upright, and it supplies food, water, and air to the roots. Some soils are already capable of meeting these purposes and can be used with little amendment. Called loam soils, they contain a mixture of different-size soil particles and organic matter. Beneficial microorganisms help break organic matter into nutrient-rich soil with good texture. If you have a garden with rich, fertile soil, you won't need to treat it.

Most garden soil needs assistance in the form of fertilizers.
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Most garden soil needs assistance in the form of fertilizers.

It is possible, however, that you'll need to improve one or more of the conditions of your soil. For example, soil with a significant proportion of clay (at or above 25 percent) is made up of rock particles so tiny and close together they allow little air circulation. Clay retains more moisture, so it takes longer to dry in spring and may need less watering in summer. It can be made richer and more likely to produce lush growth with just the addition of compost and, occasionally, a little fertilizer. The compost is important. It helps break up clay so the soil won't be too thick and poorly aerated.


Sandy soil contains larger rock particles. Air is present in abundance in sandy soil, but water runs straight through, sometimes carrying nutrients away too rapidly and drying out soon after a rain. This means that in rainy climates, the gardener may have to add everything the plants need.

The texture of your garden soil needs to be the right balance of sand, silt, and clay. Learn how to assess the texture of your garden soil on the next page.

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