Which Soil Is Right for Your Garden?

Home & Family
on February 8, 2012

Soil is more than just dirt when it comes to gardening. Just as different plants need different degrees of sunlight, your soil choice can affect your plants’ growth and development. The differences between potting soil and topsoil are important for every gardener to know. The USDA states, “The physical properties of soils affect the type and amount of vegetation that can grow in a given location.”

What is potting soil? Depending on whom you ask, potting soil will contain either no soil (dirt) or only some soil. The term potting soil also is used interchangeably with the term potting mix on occasion. Either term refers to a mixture that works best for container plants. Using potting soil in bedding plants can create too much drainage, causing your plants to lose moisture. There are different types of potting soils for different types of plants. Don’t use an orchid mix potting soil for your cactus plants, for example.

Components of potting soil. Potting soil or mix typically will contain lightweight materials that will allow excellent drainage and air circulation for your container plants. Commercial potting soils or mixes may contain vermiculite, perlite and peat moss. Vermiculite is mica, a lightweight mineral, and perlite is granular volcanic rock. Peat, or peat moss, comes from sphagnum (Spanish moss) or sedge peat. Spanish moss often is used for lining hanging baskets. Other ingredients often used in the mixture are compost, sand, barks and bone meal.

Topsoil basics. Topsoil generally is used for bedding and garden areas. Topsoil is different from loam. Topsoil is the top or uppermost soil layer in your garden area. It may be darker than the soil beneath it because this top layer accumulates organic matter and this is good for your plants. Loam, according to the University of Connecticut Extension Office, is a textural classification referring to the amount of sand, silt and clay in a soil.

Buying topsoil. When buying topsoil, it should always be debris free. Topsoil needs to contain some organic matter but not too much, because it can make the soil more susceptible to compaction, which can affect plant health. The amount of organic matter your topsoil may need will depend on your location and native soil composition. Organic matter is important in topsoil as it provides necessary nutrients for your plants and helps with the water flow through the soil. The University of Connecticut Extension Office recommends avoiding very dark and grayish topsoil as it may have come from wetland areas, making it “very acidic and poorly structured.”

Planting your plants in the correct soil medium can mean the difference between a healthy, thriving plant and one that won’t make it through the growing season.

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