The Difference Between Potting Mix and Potting Soil—and When to Use Each

When shopping at your local gardening center or plant nursery, you'll probably come upon hefty bags of potting soil and potting mix. They tend to look the same, and you might think you'll just pick up the cheaper of the two and haul it into your cart. But before you do that, you should know there is a real difference between potting mix and potting soil—and they have preferred gardening applications that will make your plants thrive if you know which one to use. Ahead, we spoke with gardening pros to help us understand the difference between these two similar growing media and when you should use potting soil vs. potting mix for your gardening needs.

What Is Potting Mix?

Contrary to what you might think, potting mix contains no soil whatsoever. It is a blend of materials like peat moss and perlite used to help with drainage and aeration, as well as bark or coconut coir for some added structure, according to Misti Mathis, co-owner of Harvest Gold Organics. "Potting mix is a lightweight, soilless blend made specifically for container plants," she says. "Think of it as a carefully curated space for your plant's roots."

What Is Potting Soil?

Potting soil, on the other hand, does contain dirt and soil and is typically denser than potting mix. It also can contain other materials like compost, peat moss, perlite, and vermiculite, says Parker Garlitz, managing partner at True Leaf Market. "These mixes are not sterile, as they have some potential to contain soil-borne pests, diseases, or weed seeds," Garlitz says.

The Main Differences Between Potting Mix vs. Potting Soil

There are a few key differences between potting mix and potting soil that home gardeners should be aware of before purchasing one or the other. First, both types of mixes offer different drainage capabilities—this is where potting mix really shines, says Mathis. "Potting mix is king here," she says. "Its ingredients are chosen to prevent waterlogging, which is crucial for healthy container plants."

Second, because potting mix does not contain any soil or dirt, it's a sterile mixture that reduces the risk of plant diseases or pests. Potting soil's composition of soil and compost means that it can also harbor unwanted pests or weed seeds.

How to Choose the Right Growing Medium

Both potting mix and potting soil have their unique strengths—potting mix is great for providing superior drainage, while potting soil is nutrient-rich due to its composition, for instance. Here's when to use each growing medium.

Houseplants

Due to its good drainage and aeration, potting mix should be used for your houseplants. Be sure to read the label though—some potting mixes are for very specific types of plants like succulents, cacti, or orchids.

Garden Beds

Both raised beds and in-ground beds can benefit from using potting soil. "Potting soil shines in outdoor gardens where drainage is less critical," says Mathis. "You can amend it with compost for extra nutrients, making it a good choice for raised beds or in-ground planting."

Seed Starting

If you're looking to start seeds indoors, you'll want to start with a soilless potting mix. Seedlings also benefit from potting mix as well, according to Garlitz.

Outdoor Container Gardening

The size of your containers might dictate which growing medium you use. Potting mix is great for small containers, but if you're using larger containers, you'll have to make sure to keep it well-watered. "[Potting mix] can also be used in large containers but may be susceptible to quickly drying out in outdoor conditions with its light and airy texture," says Garlitz. That said, potting soil might be the better choice for especially large outdoor containers. "The heavier soil content can help it retain more moisture, especially with compost, peat moss, or coco coir included," Garlitz says.