Base Ingredients of Potting
The base ingredients of a soil are the substances that make up the bulk of the soil itself. These are the ingredients that are most responsible for the soil’s physical properties and texture. Some of these also make up the backbone of the nutrient content.
Sphagnum peat moss
Sphagnum peat moss has been a popular soil additive since the inception of potting soils. The physical properties of peat moss allow for high moisture retention, as well as high oxygen content. This combination of water and oxygen retention makes a great environment for developing roots and is the main reason peat moss is the most popular ingredient in premade potting soils. It is not uncommon for peat moss to make up 30 to 60% of a premade soil mixture.
Coco coir
Many soil companies are incorporating coco coir (coconut husks) as either the base or secondary ingredient in their potting soil mixes. Coco coir is a by-product of the coconut industry and is more environmentally friendly than sphagnum peat moss. It is able to hold moisture and oxygen like peat moss; in fact, it actually has slightly higher oxygen retention. This fact alone has made coco coir’s popularity increase among indoor gardeners and greenhouse horticulturalists.
Compost
Compost is a general term referring to aged and broken down organic matter. It can be made from a number of different sources, but it’s usually derived from plant material or manure. Although compost usually isn’t used in as high of a volume as peat moss or coco coir, its role as a base ingredient is just as crucial. Not only does compost have significant nutrient value, but it also provides an abundance of microbial life to the soil mixture. These beneficial microorganisms are the foundation for nutrient uptake and the stimulation of root development.
Worm castings
Like compost, worm castings—or, vermicompost—are a significant source of nutrient value and beneficial microorganisms. Revered by many organic growers as the best soil additive available, worm castings are known to enrich soils and improve disease resistance in crops. If you choose to use worm castings as an ingredient in your potting soil, be sure to purchase pure worm castings. There are many products on the market that are labeled as worm castings but only contain a small percentage of actual worm castings in their composition.
