While it's possible to garden without giving much thought to the dirt under your feet, having a basic understanding of various soil types can make your planting more productive. Some soils are naturally rich and productive while others will benefit from the addition of organic materials that will improve quality and drainage. Although soils fall into five main categories: clay, sand, loam, chalk and peat, most soils will be a combination of at least two different types.
Clay soil is often nutrient-rich, but it can be a challenge for gardeners. Clay, comprised of very fine particles, doesn't drain well and can be difficult to work. During the summers, clay can be rock hard but turn slick and sticky when it rains. However, clay can be very productive with the addition of amendments that generally include organic materials such as manure, compost, leaf mold or sand.
Large particles formed from granite, quartz, shale and other weathered rocks comprise sand, giving it a gritty, sharp feel when you rub the soil between your fingers. While easy to work any time of year, it drains so quickly that it washes nutrients away. Successful growing in sand requires frequent addition of compost and manure to improve moisture retention.
Loam is the ideal combination of clay and sand, with the moisture retentive qualities of clay, plus sand that allows the soil to stay loose and workable without becoming compacted in damp weather. Although loam can support a wide variety of plants, the quality of loam depends on the percentage of clay or sand present in the soil.
Chalky soil is rocky, nutrient-poor and very difficult to cultivate. It becomes damp and sticky in damp weather and dry and unproductive in warm weather. Without frequent, substantial addition of organic material and fertilizer, plants grown in chalky soil often suffer from yellowed foliage and stunted growth.
Peat is an uncommon soil, rich in nutrients and organic materials formed from thousands of years of alternating plant growth and decay. Peat is easy to manage as long as it remains damp. Once peat is allowed to dry, it can be very difficult to rewater.