Potting Soil for Indoor Plants: It’s More Than Just Dirt
Isn’t the potting soil that you buy from the store the same as what you can get for free in your backyard? Can you use them both indoors?
The answer is a simple one: no.
Depending on where you live, the soil found in your yard is a mixture of silt, sand, and clay. Most potting soils sold at home improvement or garden stores are not actually “soils” at all – they are a mix of ingredients that assist a plant in growing. Potting soils are the best choice for indoor plants, as they allow for good, constant growth.
A good potting soil has an open structure, which allows air to reach the roots while also capturing the water that is essential for plant growth. It must have added plant foods and a suitable pH that is balanced between alkaline and acidic conditions. Backyard soils do not have a suitable structure or nutrients for indoor plants. Additionally, they also present the unwanted risk of weeds, pests, and diseases.
Many potting soils are mostly composed of peat – the layered accumulation of partially degraded organic material over a long period of time. Another commonly used ingredient in potting soil is coir, or the outer husks of coconuts. Once the husks are washed to remove any natural salts, coir is dried and compressed. Coir retains water very well – sometimes even better than peat in some instances – especially for seedlings.
Two other options in potting mixes are bark and wood fiber. They are easily transported and lightweight, but their age may hinder their usefulness. Bark must be aged properly, yet potting soils with wood fibers included in them must be used within months. After sitting on the shelf or in storage, bagged potting soils may lock up nitrogen in the wood. Once the bag is opened, the nitrogen is lost and your plants will starve due to lack of this vital nutrient.