Learn how to make your own soilless potting mix at home! Commercial bagged soils are pricey, and if you use a lot, can add up to significant costs. They also vary greatly in quality and, in some cases, their fertilizer strength can be toxic to plants and cause burns to plant roots. It’s satisfying to make your own mix to give your plants a healthy start—and it leads to fewer headaches. Here’s our basic DIY potting mix recipe.
Containers are great for several reasons—they’re versatile and space-saving, and they allow you to be more efficient in your use of resources. If you have a small garden space or live in an apartment with a balcony or rooftop, containers are for you.
What Is Potting Mix?
For containers, you’ll often read that you need to buy or make a good potting mix. But what does this mean?
Potting mix is not garden soil—which is heavy and includes sand, clay, and other cheaper additives that won’t work for containers. Some people may refer to it as potting soil, yet potting mix is soilless. It’s lighter and fluffier than ground soil to allow enough air and water for healthy root growth and also provides enough anchorage for roots. These soilless mixes are sterile, so there is no chance of introducing pest or disease problems.
Potting mix can certainly be bought in bags at garden stores. Look for “Soilless Potting Mix,” which generally includes three ingredients: 1) peat moss or coconut coir for moisture and nutrient retention, 2) pine bark for anchorage, and 3) either perlite or vermiculite for air space, which makes the texture light and fluffy. Some potting mix also includes fertilizer or moisture-retaining treatments. If you use a potting mix with fertilizer, you’ll need to adjust the fertilizer you provide. (Think of salted butter versus unsalted butter in a recipe!)
But many gardeners who plant a LOT of containers or raised beds or start seeds indoors will mix up their own potting mixes! For the number of containers I use in my garden, I learned long ago that it’s much cheaper to make my own potting mix and store it in an extra trash can rather than pay for several big sacks of premade potting mix. Plus, I can customize the mix for a variety of different plants.
Before Making Your Own Potting Mix
Before we go any further, note that if you only need a few small containers’ worth of potting mix, you may actually be better off buying a premade mix! Making your own is usually only economical on a large scale. Here are a few things to keep in mind before creating your own mix:
When it comes to any potting mix, the lighter it is, the better. Loose and porous mixtures not only make a container lighter to move, but they also transport water, fertilizer, and air to plant roots more quickly and allow for good drainage, which is important for container gardening.
Start with the basic recipe below and then add soil sulfur to lower the pH or lime to raise the pH, according to the needs of your plants. Both additives can typically be found at garden centers. Plants such as lettuce, Russian sage, and marigolds prefer sweet soil with a pH of about 7.5, while others are acid lovers, like ferns, asters, and strawberries. They need a pH of about 5.5 to 6.0. Here’s a list of more plants’ pH preferences.
If rapid drainage is needed, as is the case for cacti, succulents, and lavender, add extra sand and perlite.
If greater moisture retention is needed, as is the case for ferns and woodland flowers (like primrose) add extra vermiculite or coconut coir.
Potting mix is sold by volume (typically measured in quarts), and most pots are measured by their diameter. To translate quarts of mix into various pot sizes, use this quick reference:
I'm doing my first container garden. I bought a Big Bag raised bed, which is 50" in diameter and 12" deep. How much potting mix will I need, and can you give me a recipe that won't break the bank? I'm planting tomatoes, peppers, cucumbers, summer squash. Thank you for your help.
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<span>Hui</span>Wed, 05/28/2014 - 16:03
I don't know very much about gardening. I just bought some organic gardening mix. I am wondering, can I use it directly for planting tomatoes in a pot? Do I have to mix it with native soil or anything else? I don't have good soil at all at home...Thanks in advance for your help
No you can just use that straight out the bag perfect the way it is I wouldn't even add fertilizer for a month or so
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<span>Dennis Early</span>Thu, 05/08/2014 - 09:50
I start and transplant about 400 veg and flowers from seeds. I use Bordines potting mix and use 6 bags at 3 cu ft each. $22 and change is getting expensive. Can I mix my own for this volume and cheaper? Also is the compost you buy in bags safe for seeds? Thank You, Dennis
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<span>Doreen G. Howard</span>Thu, 05/08/2014 - 20:38
Bagged compost is weed-free, from my 20 years experience of using it. Price the materials to make your own potting mix to see if it's cheaper to make your own. Prices vary so much by region, I'd hate to say it's cheaper.
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<span>Jddred</span>Wed, 05/07/2014 - 12:00
I am using a wooden box approximately 24" x 120" for a garden of fruits and vegetable. Would this type of mix work or what would you recommend?
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<span>Doreen G. Howard</span>Wed, 05/07/2014 - 15:22
For raised gardens, layer top soil, composted cow manure, peat moss and a double layer of compost. At the start of every season, add more compost.
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