Most people refer to these three mediums interchangeably. At least, I did. I refused to believe that any ol’ plant could not grow in any ol’ soil. I mean… plants grow in dirt… right? Well, we all start somewhere with our plant growing expertise. Turns out, there is more to it than I thought. Garden soil, Potting Soil, and Potting Mix have very different ingredients and your plants will notice, especially when it comes to container gardening. Here’s what I’ve learned.
The Big Difference
To put it simply, garden soil and potting soil are planting mediums that contain soil–– one used in the ground, the latter meant for pots. They can sometimes be purely dirt, like garden soil, and sometimes it is mixed with other organic materials, like potting soil. Potting mix, however, contains no soil at all. Instead, the potting mix is soil-less and contains other ingredients that create a structure specifically meant to support potted plant sprouting and growth. These ingredients can include vermiculite, perlite, coir, peat moss, sphagnum moss, and so on. Think of it as a spectrum from plain dirt to rich nutrients, with Garden Soil on one end and Potting Mix on the other. Potting Soil is somewhere in between.
Pros of Garden Soil
- Affordable: Garden soil is generally less expensive at your local garden center, or you can just grab a shovel and get some soil from your garden. However, your indoor plants need something with more nutrients and structure, so don’t opt for this cheapest choice at the expense of your plants’ health.
- Heavy: While it may not seem like a benefit at first, the heaviness of garden soil can keep your plants sturdy during windy weather. This is especially important for plants that don’t have substantial root systems yet.
- Holds Water: Garden soil is known for holding water – this is a double-edged sword. It can keep plants from dehydrating during dry/warm temperatures, but it can also be a breeding ground for fungus, root rot, and pathogens. You may notice that your soil is wet when you open the bag.
- Natural & Long-Lasting: Garden soil is natural and compost-based, though may need to be fertilized from time to time. It will always be usable, adding a helpful top layer to your outdoor garden.
- Organic Options: Because garden soil is natural there are many great options that are fully organic.
Drawbacks of Garden Soil
- Lacks Complex Nutrients: Garden soil is meant to be mixed with the natural dirt found in your yard, not as a growing medium on its own. The nutrients that are present are important for your garden but will need to be supplemented with fertilizer over time.
- Should Not Be Used for Potted Plants: Garden soil does not typically have the nutrient content, nor the structure to support potted plants. The dirt will become heavy, compact, and waterlogged, likely suffocating and starving your plant. Use with outdoor, in-ground gardens only.
Where To Buy Garden Soil
Garden soil can be found at any home improvement store like Home Depot or Lowe’s, along with every local nurseries and garden centers. Sometimes retailers will even give this away for free. There are also a number of composting services that can provide fresh garden soil.
When to Use Garden Soil
Garden soil should be used exclusively on outdoor gardens planted in the ground. Mix this with the topsoil in the garden bed, surrounding freshly planted vegetation. You can also use garden soil to fill the low spots in your yard with higher quality soil. Fertilize and water as needed and add other growing mediums (such as peat moss) to help with drainage.
Pros of Potting Soil
- Affordable: Potting soil is generally inexpensive at your local garden center. However, your indoor plants care more about the ingredients than the price, so be sure to read carefully.
- Nutrient-Rich & Long-Lasting: It may need to be fertilized from time to time, but potting soil is nutrient-rich and it will always be usable. Whereas potting mix will eventually break down and lose all nutrient value.
- Organic Options: Because potting soil is natural there are many great options that are fully organic.
Drawbacks of Potting Soil
- Poor Drainage: Potting soil can get dense and will compact over time. This compacting can prevent proper drainage and cause your plants to become waterlogged. This is why it is not always ideal for potted plants.
- Poor Aeration: Growing media for pots should be light and fluffy to allow the root system to spread as much as possible and to receive proper airflow. Most Potting soil lacks proper amounts of ingredients such as perlite and vermiculite which support lightness and drainage.
- Not Ideal for Seed Starting: Because of the reasons above, potting soil is not an ideal growing medium for seed starting.
Where To Buy Potting Soil
Potting soil can be found at any home improvement store like Home Depot or Lowe’s, along with any local nurseries and garden centers. Sometimes retailers will even give this away for free. It can also be found through several online retailers.
When to Use Potting Soil
You can use potting soil for your outdoor raised beds or as topsoil if you’d like to fill the low spots in your yard with a higher quality soil. Because it is so nutrient-rich, organic potting soil is also ideal for use in your composting and worm casting.
Pros of Potting Mix
- Great Drainage + Balanced Water Retention: A good potting mix is a soil-less mix of light ingredients that allow for drainage and do not compact over time. A pot with propper drainage holes along with the correct potting mix will allow the roots of your potted plant to absorb moisture without becoming waterlogged.
- Great Aeration: Ingredients such as peat moss, allow proper airflow as well as drainage for happy roots that can spread freely.
- Nutrient Mix: With a potting mix, you get just the right mix of nutrition for your plant’s growing needs. You won’t be left guessing, as with natural soils.
- Customizable for Your Plant Type: There are potting mixtures for succulents, cacti, roses, seed starting, and beyond. Because every plant has different needs, there are as many varieties of potting mix.
Drawbacks of Potting Mix
- Breaks Down: Because potting mix contains no natural soil, its organic matter will break down over time and its nutritional value will run out. This will make fertilizing essential and repotting your container plants possibly inevitable.
- More Expensive: These mixes, because they contain so many essential ingredients, can be more expensive.
When to Use Potting Mix
Potting mix is perfect for your indoor plants as well as outdoor container plants. Plants such as cacti and succulents are in particular need of a potting mix as they have very specific needs. Potting mixes can lack the structure to support an outdoor garden bed and can be too pricey to justify filling your yard with them.
Where To Buy Potting Mix
Potting soil can be found at any home improvement store like Home Depot or Lowe’s, along with most local nurseries and garden centers. Since there are several kinds of potting mix to match your specific plant particulars, internet shopping is the easiest way to get exactly what you need.
When to Re-pot or Change Your Potting Soil/Mix
Whatever growing medium you choose, it will not last forever and will likely need to be replaced and refreshed. Garden soil can be left in the ground, but fresh soil should be added when planting something new or simply filling in holes in your garden or yard. Otherwise, fertilizer will be most helpful.
Over time, if your plant stops thriving or if the potting soil is too compact and doesn’t retain moisture, it’s probably depleted and should be replaced. The same is true of potting mix, though this is likely to be noticeable sooner. Healthy potting soil and mix should be loose and fluffy.
A good time to refresh your growing medium is anytime you need to re-pot your plant since the roots and dirt will be loosened and changed anyway. Plants typically need to be repotted every 12 to 18 months, depending on how actively they are growing. Some slow growers can use the same pot for years but will still require soil replenishing. Early spring, before the start of the growing season, is usually the best time to re-pot your houseplants. This is a great and natural time to introduce new potting soil or potting mix.
The Best Potting Soil & Mix Brands For HousePlants
There are nearly endless varieties of soils and mixes to meet any of your houseplant needs. Here are a few of our favorites!