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:
<a title="View user profile." href="/author/editors">The Editors</a>Fri, 04/21/2017 - 12:00
You can certainly use coconut coir, but you should use it in placement of the peat moss.
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<span>Aurora</span>Fri, 03/24/2017 - 13:49
According to the Farmer's Almanac website, my bell peppers want loamy soil with a pH between 5.8 and 6.5. Would your standard recipe work for the peppers or would I need to add some sulfur to lower the pH? If so, how much sulfur would you recommend? I tried adding sulfur to a potting container for hydrangeas once and I just ended up burning them to death : ( Don't want to get the same results for my peppers.
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<a title="View user profile." href="/author/editors">The Editors</a>Fri, 03/24/2017 - 16:48
The basic container mix recipe above should be at about neutral (7.0), or perhaps a tad acidic if the lime didn't compensate quite enough for the peat. Before you add the 1/2 cup lime, mix in all the other ingredients and then test the pH (soil test kits are available at garden centers). This will tell you whether you are within the 5.8 to 6.5 range or if you need to add just a little lime to move it back toward neutral a bit. Hope this helps!
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<span>Joe Leach</span>Wed, 03/22/2017 - 20:06
In your above mix recipe would I use a regular measuring cup that measures dry ingredients? For example the 1/2 cup of lime. I would use a 1/2 cup using a dry ingredient measuring cup? Correct? Thanks
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<a title="View user profile." href="/author/editors">The Editors</a>Thu, 03/23/2017 - 13:09
You'd probably find that a dry ingredient measuring cup might be more convenient, since it is made for the ingredients to fill to the top, so that you can level it off. However, you can also use a measuring cup meant for liquid ingredients. This type is a little harder to keep the top of the dry material level, since the top measure line falls below the rim, but for potting mixes, it should work fine. Either would be a good addition to your gardening tool collection.
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<span>Debbie</span>Mon, 06/20/2016 - 19:23
Would this recipe work or container roses?
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<a title="View user profile." href="/author/editors">The Editors</a>Wed, 06/22/2016 - 16:48
Yes, it could be used. You may need to do some supplemental fertilizing.
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<span>Nathan N.</span>Thu, 03/24/2016 - 21:30
Is the 2 cups of time release fertilizer right in tbe recipe? The reason I ask is that my time release fertilizer (basic 3 month type) calls for about a cup for 50 square foot beds mixed into the top 6-8 inches. The recipe above is for about 1 cubic foot which is far more concentrated. I have already potted veggies. I am just double checking that it does not hurt my plants...
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<a title="View user profile." href="/author/editors">The Editors</a>Mon, 03/28/2016 - 15:38
Hi Nathan,
The 2 cups of fertilizer is accurate. You mix this into the entire 1 cubic foot of potting mix.
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<span>Free</span>Tue, 05/19/2015 - 22:04
Please help me! I live in zone 8b, and I would like to start a garden. I have a few questions before I get started. I've read so much that now I'm feeling confused....meanwhile I have a table of plants staring at me....
1. I'm pretty sure I can plant 2 determinate tomatoes and strawberries in a 55gallon barrel/ garden tower. Can Bush string beans go in too, or do they not like acidic soil? If so, would the beans go in the bottom?
2. I want to make my own potting mix. I want to use 6cuft sphagnum peat moss, 3cuft Kellogg Raised Bed Mix, 1cuft Bagged garden compost, 1cuft steer manure compost, 1 cuft sand and some red wrigglers. I don't want to spend $24 on vermiculite :'( will this work? If not please fix my "recipe" :-)
3. I want to grow sweet potatoes in an old tub.Is there a certain potting mix I should use or is mines ok?
4.Lastly, I would like to get some carrots somewhere in there if possible :-D
THANKS IN ADVANCE FOR ANY HELP OR TIPS!
You can certainly use coconut coir, but you should use it in placement of the peat moss.