Soil and Potting Soil

When you go to the garden store, you’ll see a lot of different types of soil and potting mix. Some of these are sterile and inert, while others contain microorganisms that help create the right conditions for plants. It’s important to understand what you’re buying before you buy it.

Topsoil is a natural, loose-textured soil, usually rich in nutrients, and typically enriched with compost and other organic matter. This material is used for planting in the ground or as a mulch on lawns and landscape beds. It can contain a variety of materials, including wood chips, aged manure, rotted straw and composted bark from mill operations.

Potting Soil is a mixture of sphagnum peat moss and other plant or animal-based organic materials that are either decomposed or partially decomposed, says Karen Bachman Thull, a Twin Cities gardening expert who works at Bachman’s Floral, Gift & Garden. The most common of these ingredients is peat moss, which is a naturally occurring material that has been harvested from bogs.

What’s the Difference Between Soil and Potting Soil?

Some other ingredients include organic plant and animal-based fertilizers, such as alfalfa meal, bone meal or kelp meal. Many potting soils also contain perlite, vermiculite and other aeration agents, which improve drainage and air movement.

Some potting mixes are sterile, meaning they have no pathogens, weed seeds or fungi. These soils are best for growing plants in containers and for starting seedlings because they facilitate good air movement, avoid weeds and provide optimal pH levels.

Soilless potting mixes are also easier to get into the car and keep from compacting when you’re transporting them. However, they tend to be heavy and may not drain well if they’re wet. Soilless potting mixes aren’t ideal for planting in the ground because they can get clogged with soil particles that prevent good drainage, according to Kathy Low, an associate professor at the University of California.

The aeration and drainage benefits of potting soils are often overlooked, especially for outdoor planting. They’re ideal for cactus and citrus planting because they allow water to move freely through the soil. They can also hold up to more heat than potting soils made from peat moss, which is why some plant experts recommend these mixes for indoor use.

Garden soil is the same type of loose-textured soil that you’ll find in your yard, but it usually contains more sand or clay than potting soil. It’s a more affordable alternative to potting soil because it doesn’t contain pricier ingredients like perlite, vermiculite or moss.

It is more nutrient-dense, says Low, and it can be a source of organic matter that improves the texture of the soil in garden beds. It can also be a more economical way to fill in low spots in raised beds because it doesn’t need to be enriched with soil-less materials, she adds.

It can also be more environmentally sustainable than peat moss, says Low. Some potting soils are made with renewable resources, such as coconut coir or rice hulls. These types of potting soils are also less expensive than peat moss and are a good option for gardeners who want to reduce their impact on the environment.