Which should you choose, potting soil or topsoil? I’d like to start this post with a story: A couple of weekends ago, we had a truckload (12 yards) of topsoil from a local supplier delivered to our house. I had brought it in to fill our new raised garden bed and to supplement our existing flower beds. Many people asked me what the difference is between potting soil and topsoil. My goal in this blog entry is to answer this common gardening question.
Topsoil is typically manufactured using a combination of local ingredients. The soil is blended by combining two or more of the following: a local loam (a local soil typically from a construction site), compost, sand (typically from a sand pit), peat moss (often local), sawdust and garden mulch (less composted garden waste).
In contrast, Black Gold potting soils are manufactured using a combination of Canadian Sphagnum Peat Moss, coconut fibers (coir), earthworm castings, forest humus (composted bark and other wood products), compost, perlite, pumice and added fertilizer. It’s richer, more consistent, and higher quality.
Topsoil is manufactured using mineral soil (natural loam), while potting soils are manufactured without loam soils, and are often referred to as soilless growing mediums. Topsoil is manufactured without the use of an aggregate, whereas Black Gold potting soils use both perlite and pumice. Aggregates are added to potting soils to increase soil air capacity, which helps the roots breath. Most topsoils also do not come with a fertilizer incorporated in them, while all Black Gold potting soils contain fertilizer. Also it is important to consider the bulk density (the weight) of the two products. Topsoil is typically very heavy while potting soil is significantly lighter.
What does this mean? It means that topsoils are designed to be garden fillers or extenders but are not designed for use in a container or hanging baskets. Topsoil often needs additional amendments as well. For example, I added Black Gold Earthworm Castings and tomato and vegetable fertilizer to my raised bed before I planted my garden.
Black Gold potting soils are designed to be used in indoor or outdoor containers or hanging baskets. High-quality potting soils are designed to create the complete ideal growing environment for your plants. Then all they need are sunshine, water, fertilization, and loving care (deadheading, grooming, etc).
Topsoil also allows you to get well acquainted with your wheelbarrow and the joy of finishing the day with a sore back. Unlike potting soil, you need to find a home for all the product you purchased, because your spouse and the neighbors probably would not like to see a permanent dirt pile in your front yard.