Difference Between Potting Soil and Potting Mix

Potting soil and potting mix are the two most commonly used gardening media, but you may be wondering exactly what the difference is between the two. Because the terms are often used interchangeably, people can get confused and make mistakes when shopping for these products. The key to a successful potting mix purchase is understanding the differences between the two and how they can affect your plants.

Potted plants need to have a growing medium with the correct nutrient levels, moisture and air flow properties. The wrong potting medium can lead to poor plant growth and a range of other problems. The main difference between potting soil and potting mix is that the former is an entirely soil-less product while the latter is composed of organic material, such as peat moss, pine bark, sphagnum moss and other elements to improve drainage.

The best Potting Soil is lightweight and fluffy, providing the right aeration for the roots to grow. It can also absorb and retain water well, making it an ideal choice for most plants. Some potting mixes have added bulking materials, such as coir, to prevent heavy water saturation that can harm the root systems of your plants. Other add-ins, like perlite and vermiculite, provide better drainage that doesn’t trap water and drown the roots.

The Difference Between Potting Soil and Potting Mix

While a good quality potting mix can work for most plants, the addition of these bulking materials can increase the risk of pest infestation and fungus problems. It’s important to read the ingredients list and understand why the materials were added, especially if you are planning to use these products in a container garden or raised bed.

The most obvious difference between potting soil and potting mix, says Karen Bachman Thull of Bachman’s Floral, Gift & Garden, is that potting soil contains garden soil, minerals and organic matter. It’s not considered sterile and can attract fungus gnats, which can be detrimental to indoor plants. It’s also not a good choice for raised beds or flower beds.

If you’re looking for a potting soil, look for one with a OMRI (Organic Materials Review Institute) certification that certifies the organic content of the product. This certification is designed to protect the environment while providing the same nutrients as a fully organic potting soil.

There are many types of potting soil, from all-purpose potting mixes to ones formulated specifically for particular plant families. Some include small crystals for water retention, while others contain fertilizers specifically geared towards one type of plant or flower, from roses to cacti to hydrangeas.

For example, a mix for hydrangeas might be made with a blend of compost, sphagnum moss and ground pine bark, while a potting soil formulated for cacti might have pulverized limestone as an additive to neutralize the pH level of the peat moss. The best potting mix is lightweight and fluffy, offering the right aeration for the roots, to provide the correct nutrient levels, moisture and even air flow properties. It can also absorb and retain water well, providing it with the ability to hold up under pressure and keep the roots healthy.