Making sure you have the right substrate (potting media) is the foundation of successful houseplant care. It’s not just dirt!
Substrate holds the plant in place, provides nutrients to the roots, and perhaps most importantly has a strategic role in how much water and air is available to the roots. The wrong mix could play a part in leading to root rot or desiccation of your plant.
Organic Potting Soil
For many houseplants, an organic potting soil, such as the one we recommend by E.B. Stone is a great place to start. Such a mix will come with a lot of good things mixed in to provide structure and nutrients. Usually you’ll find soil, bark, perlite or pumice, natural slow release organic fertilizer, and other similar ingredients. Potting soil would work well as a basic substrate for a wide variety of herbaceous (leafy) plants, such as philodendrons, pothos, Chinese evergreens, ferns, and calatheas.
Here are the specific ingredients of our favorite potting soil by E. B. Stone:
E.B. Stone Organics Edna's Best Potting Soil is a special blend of the finest 100% natural & organic ingredients formulated to make a superior mix for both indoor and outdoor container gardens. E.B. Stone Organics Edna's Best Potting Soil is ready to use right out of the bag. This potting soil has excellent moisture retention and air-filled pore space encouraging root growth. A natural wetting agent, Yucca schidigera saponin has been added, allowing the mix to rehydrate during each watering.
Contains: Aged Fir Bark, Aged Redwood, Sphagnum Peat Moss, Pumice, Earthworm Castings, Sand, Feather Meal, Oyster Shell Lim (pH adjuster), Dolomite Lime (pH adjuster), Bat Guano, Alfalfa Meal, Kelp Meal, and wetting agent (yucca schdigera saponin). For best results, always use our Sure Start.
If you are interested in growing epiphytes (plants that grow on trees for support in the wild), such as orchids, you could use bark as a substrate or even mount them onto a wooden board. Sphagnum moss can help with extra water retention.
Cacti and Some Succulents
For plants that need a very minimal amount of water, including certain succulents and most cacti, sand may be the perfect substrate. Cacti will rot very fast if any water sits at their roots. Sand, being comprised of tiny rocks and glass, doesn’t have the ability to absorb water.
If a succulent needs more water retention than sand offers, but still less than a regular potting soil, a succulent mix could be perfect! These mixes are made with fast drainage in mind. They are usually a mix of potting soil, sand, bark, and perlite or pumice.
African violets have their own specialized substrate mixes that includes fertilizer that helps them to stay healthy and bloom. It has very little or no actual soil, being comprised mostly of peat and perlite. This allows great drainage for sensitive African violet roots.
Carnivorous plants enjoy a half and half ratio of peat and perlite, but prefer no fertilizer since their roots are very sensitive to any nutrients or minerals. It might be helpful to realize that they naturally occur in nutrient-poor peat bogs, which is why they developed the adaptation of digesting insects.
Serious aroid collectors like to mix their own special mix for their plants. This mix allows more air to reach the aroid’s roots. The aroid family includes (but isn’t limited to) philodendrons, anthuriums, pothos, peace lilies, monsteras, syngoniums, and zz plants.
Steve Lucas (a well known plant specialist) recommends the following mix for growing aroids: 30% potting soil, 20% peat, 40% bark, 10% Perlite / Shredded sphagnum moss, some handfuls of horticultural charcoal.
To add air / drainage add bark, perlite, or pumice. To increase water retention add sphagnum moss, peat moss, or vermiculite. A bit of horticultural charcoal can be added to keep the soil “sweet,” meaning it filters impurities.