The Best Types of Soil for Plant Growth

Soil Texture

• Soils are commonly divided into three textures: sand, silt and clay. Sandy soils have the largest soil particles with large spaces between them. Clay soils have the smallest particles and pores. Silt soils have a medium texture. For most gardening purposes, loam soil conditions are ideal. A loam soil has a proportional balance of sand, silt and clay. According to the University of Connecticut Cooperative Extension System, a loam soil has approximately 7 to 27 percent clay, 28 to 50 percent silt and less than 52 percent sand.

Soil pH

• Soils are also classified based on their acidity or alkalinity. A soil with a pH of seven is considered neutral. Those with pH levels below seven are acidic, and soils with pH above seven are considered alkaline. According to the Colorado State University Extension, pH levels between 6.0 and 7.5 are desirable for most plants. However, some plants require more extreme soil pH conditions. Blueberries, for example, require acidic soils with pH levels between 5.0 and 5.5, which is too low for most other plants.

Water Retention

• Soil must also have appropriate water retention to support plant life. Water retention is primarily influenced by soil texture. Clay soils tend to have high water retention, whereas sandy soils have very low water retention. Most plants require well-drained soil conditions, which are found in loamy soils with plenty of organic matter. However, other plants, like cacti, require low water retention, which is found in loose, sandy soils with large pores between soil particles.

Organic Matter

• Organic matter refers to a variety of substances that are found or incorporated into soils, such as peat, compost, manure and cover crops. The amount of organic matter in the soil has a crucial impact on healthy plant growth. Very low amounts of organic matter may decrease soil fertility, and plants may develop nutrient deficiencies. As noted by Cornell University Extension, many gardeners consider incorporating organic matter into garden soil to be one of the most important steps to successful gardening.