Potting Soil: The Surprising Ingredients

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Lawn & Garden

Potting soil is not actually soil, but a planting medium consisting of a variety of materials. According to Paul Cunningham, hard goods buyer for Pike Nurseries & Armstrong Garden Centers, potting soil typically contains Canadian sphagnum peat moss, composted or aged bark, compost, earthworm castings, horticultural grade perlite, pumice or cinders, and controlled-release fertilizer. While single-ingredient items like peat moss or bark are not technically soil, they can be used as planting mediums for potted plants.

The reason why “soil” is left out of potting mix is because actual soil is heavier and less porous than potting soil. Potting soil needs to be lightweight to keep shipping costs down and to improve plant growth by allowing water to drain quickly and air and roots to move and grow more freely. In contrast, topsoil placed in a container stays wet and restricts air movement. Potting soil also reduces the risk of soil-borne and based insect and disease problems.

However, gardeners should not use garden soil for potted plants, as it will not drain well in the confined space of a container. Potting soil is recommended for indoor or outdoor container gardening, including glazed pots, hanging baskets, window boxes, and raised beds. Your local garden center can help determine the best potting soil for your plant selection.

Now That’s Interesting

Some gardeners prefer to make their own potting mix from scratch. Check out this YouTube video to learn how.


1. What exactly is potting soil?

Potting soil is a mixture of organic and inorganic materials that are used to grow plants in containers. It is designed to provide the necessary nutrients and growing conditions for plants to thrive in a confined space.

2. Is potting soil the same as garden soil?

No, potting soil is not the same as garden soil. Garden soil is the natural soil found in your yard, while potting soil is a specially formulated mixture that is designed to provide the necessary growing conditions for plants in containers.

3. What are the ingredients in potting soil?

The ingredients in potting soil can vary depending on the manufacturer, but they usually include a mixture of organic materials like peat moss, compost, and bark, as well as inorganic materials like perlite, vermiculite, and sand. Some potting soils may also contain fertilizers or other additives to enhance plant growth.

4. How do I choose the right potting soil?

When choosing potting soil, consider the type of plant you will be growing and its specific growing requirements. Look for a potting soil that is appropriate for the plant’s needs, such as one that is designed for succulents if you are growing cacti or other succulent plants.

5. Can I make my own potting soil?

Yes, you can make your own potting soil by mixing together organic materials like peat moss, compost, and bark, as well as inorganic materials like perlite, vermiculite, and sand. However, it can be difficult to get the right balance of nutrients and growing conditions, so it may be easier to purchase pre-made potting soil.

6. How often should I replace potting soil?

You should replace potting soil every year or two, depending on how quickly the nutrients in the soil are depleted and how quickly the soil breaks down. If you notice that your plants are not growing as well as they used to, it may be time to replace the potting soil.

7. Can I reuse potting soil?

Yes, you can reuse potting soil, but you should mix in fresh soil to replenish the nutrients and improve the growing conditions. You should also remove any dead plant material or roots from the soil before reusing it.

8. Is potting soil safe for pets?

Potting soil is generally safe for pets, but some pets may be tempted to eat it, which can cause gastrointestinal problems. To prevent this, keep potting soil out of reach of pets and consider using a pet-safe soil or covering the soil with rocks or mulch.

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