Shopping for garden supplies, you’re bound to find a bunch of different labels that sound too similar. Potting soil vs. potting mix? Is there a difference between the two?
As a matter of fact, there is! Although both products might sound like synonyms, we’ll explain the difference between the two, and how to get the one you want for your garden.
What Is Potting Mix?
Potting mix is a soilless plant-growing medium. It’s usually made of an organic material mixture that contains:
- Peat/Sphagnum moss
- Perlite
- Vermiculite
- Coco coir
- Slow-releasing fertilizers
The components of potting mixes vary by brand and by ultimate use. Some potting mixes are made for sprouting seeds, some are better for indoor gardening, and some are used for raised beds for outdoor gardening.
Potting mixes are always sterile. That means they contain no microorganisms, like bacteria or fungi, and also contain no weed seeds that can sprout with your plants.
They’re also made using specific ratios to ensure optimal hydration and drainage, which prevents issues like root rot.
What Is Potting Soil?
Potting soil is a mixture of mineral soil and other ingredients that are used to grow plants outdoors. The soil in question could be clay, sand, or loam, depending on the potting soil’s purpose.
You can find potting soil labeled as “garden soil” on shelves at the hardware or garden store. This means it’s usually relegated to raised beds in outdoor gardening and isn’t used for container gardening.
Other ingredients found in potting soil include compost, which improves the texture and nutritional value of the soil. It can also contain inorganic crystals that improve aeration and drainage.
You usually go for potting soil when the soil in your yard is of poor quality and requires too much work to improve. It’s also a more direct way of creating flower beds and rock gardens where you need a specific type of soil for your plants to thrive.
What Is the Difference Between Potting Mix vs Potting Soil?
The biggest difference between potting mix and potting soil is that potting mix has no mineral soil in it at all. Potting mix only contains organic matter, and occasionally, some large inorganic crystals of perlite or vermiculite.
The second biggest difference is the weight of the products. If you compare bags of the same volume, the potting mix would always come out lighter than potting soil. That’s because potting soil contains actual soil, which is a pretty dense substance.
If you’re confused, always look at the ingredient list of both products. Potting soil should have “garden soil,” “loam,” or “clay” listed as one of the ingredients. Potting mixes are usually made of peat moss and other organic compounds, but no soil should be listed at all.
Make sure to always check the ingredients before you add the bag to your cart. If you can’t find an ingredient list, put the bag back on the shelf.
What Is the Difference Between Potting Mix vs Garden Soil?
Garden soil is another name for potting soil that can be listed on the bag at the store. It usually has the same ingredients as potting soil. Although sometimes, it only contains mineral soil and none of the organic components.
If you’re looking for a growing medium for your container plants, then you should skip the garden/potting soil and stick with the potting mix. Indoor plants do much better in the airy, uncompacted medium of soilless growing mixes than they do in regular soil.
That said, if you’re going for a raised bed in your garden, it might not be the most cost-effective measure to use a soilless mix. Garden soil provides structure and bulk that supports outdoor growing plants, so it’s the better option here.
What Is the Difference Between Potting Mix vs Topsoil?
Topsoil is a name given to the uppermost 2–8 inches of soil. It’s not a product you can buy at the store, but rather a descriptor of the top layer of soil you have in your garden.
Topsoil doesn’t have a specific ingredient list, rather, it can be made of whatever type of soil you have on your property.
If you have clay soil in your garden topsoil would be made mostly of clay particles that clump up and form a ball when squeezed.
If you have sandy soil, the particles would be gritty and coarse, falling apart if you try to squeeze a fistful in your palm.
Lastly, if you have loamy topsoil, it would be in the sweet spot between the two. It’s compact enough to allow for good hydration and nutrition, and friable enough to provide adequate drainage.
Potting mixes don’t have that kind of differentiation because they don’t contain soil at all. They, however, can be categorized according to other factors. Let’s take a look at them!
Related reads: DIY potting soil for indoor plants
Types of Potting Mixes
Potting mixes can be made of multiple organic materials. Here are some of the ingredients that can go into a potting mix:
- Peat moss
- Pine bark
- Coco coir (aka coir fiber)
- Perlite
- Vermiculite
- Compost
The ingredients are used in different concentrations to achieve the best properties for their specific use. Types of potting mixes are:
All-purpose Potting Mix
All-purpose potting mixes are usually made to work with most container, indoor, or outdoor gardening needs. The soilless potting mix will usually consist of compost and pine bark as a base, with the addition of perlite for aeration, and fertilizer to keep the plants well-fed.
Seed Starting Potting Mix
Seeds require a growing medium with very little nutritional content. This is meant to strengthen the budding roots and shoots, making them reach further to reach food and sunlight. That means a well-draining growing medium amended with perlite or coco coir.
Moisture Holding Potting Mix
Some indoor plants require good moisture retention to thrive. Daylilies and Japanese Irises are among these plants. The growing medium they’ll thrive in should contain peat moss and a wetting agent like yucca extract.
Orchid Potting Mix
Orchids are notoriously sensitive plants that require special growing conditions. That’s why their potting medium should have superb aeration and drainage. Potting mixes that contain coconut coir, fir bark, and charcoal can all provide adequate porosity that should prevent root rot.
Related reads: Soil Mix for a Raised Garden Bed
Benefits of Potting Mix
Potting mixes have many advantages over potting soil, the biggest of which is that they’re completely sterile. How many times have you heard of someone getting soil from an untrusted source and ending up with a yard full of weeds?
You can also count on potting mixes to provide adequate drainage and prevent waterlogged soil situations. That’s because good-quality mixes are amended with specific ratios of inorganic additives that aerate the growing medium super well.
Lastly, a potting mix usually has all the nutrition built into the product with no additional requirements other than regular watering. This takes the guesswork out of growing your plants and makes for a stress-free plant parenting journey.
What Should I Consider When Selecting Soil?
Selecting soil for your gardening project has multiple considerations:
Source and Quality
You can buy soil from countless online and offline vendors. However, only a few of these sources offer you true quality soil that you can use for gardening.
Many of the people selling soil are construction companies that dig out ditches or empty lots to build houses or garages. This soil is almost always completely dry and depleted. You can only use it to fill out a hole in your yard, but not to start a garden.
Try to source your soil from someone with a gardening background and check for its quality before purchasing.
Type of Plants
The main thing you need to think of is the type of plants you intend to grow. Depending on the plant, you should look for potting or garden soil that matches it.
Learn about the plants you want to grow, find out the amount of nutrition and drainage they require, and take your pick.
Type of Garden
If you intend on planting a rose garden, you’ll need soil that’s both moisture-retentive and well-draining. On the other hand, if you want a rock garden with succulents, sandy soil with very little water retention is crucial.
Cost
Many people forget the importance of calculating costs before embarking on a new gardening adventure. Of course, you can buy the highest-quality soilless potting mix, but filling up a whole backyard with it isn’t very cost-effective.
Calculate the cost of amending the soil in your backyard vs. buying bagged soil before you decide which one you plan on doing.
Related reads: What’s the Best Soil for Lawn
Conclusion
What’s the difference between potting soil vs. potting mix?
Potting soil is made of regular garden soil as well as other ingredients like compost. Potting mix, on the other hand, is made of a soilless medium, like peat moss or pine bark, as well as other amendments for better drainage and nutrition.
You might be confused by the conflation of the two terms. However, you should always read the ingredient list on the bag before you make a purchase.