My recipe for fast-draining potting mix

I find that most commercially available cacti and succulent mixes either contain peat (which is almost impossible to rewet after it has dried out) or too much organic matter, resulting in soil that stays wet too long after watering. That, in turn, could lead to rot, especially in combination with colder weather. The only brand I feel comfortable using unamended is Black Gold Cactus Mix; the formulation for California contains 40-50% pumice, which guarantees excellent drainage.

For a while now I’ve been making my own succulent soil mix. It’s cheaper than Black Gold Cactus Mix, it allows me to control all the ingredients and ratios, and it’s fun in a geeky sort of way.

I use only three ingredients:

1 part coir
1 part commercial potting soil
2 parts pumice

Coir is the coarse fiber from the outer husk of coconuts. Check out this earlier post about coir. I like it because it loosens up the mix while adding a bit of water retention. In contrast to peat, coir rewets easily and doesn’t compress as readily.

Coir is available online in compressed bricks, which need to be rehydrated. I simply put the brick you see below in a Tubtrug filled with water, topped it with a few rocks to keep it submerged, and let it sit for a couple of days.

Compressed coconut coir brick

Rehydrated coir

The rehydrated coir went in our trusty garden cart.

Garden cart with coir…

To the coir I added the same amount of potting soil (by volume, not weight). I’m not that picky about which kind or brand except that I make sure it’s free of peat. As I mentioned earlier, peat is hard to rewet after it has dried out, and when wet it holds moisture longer than is desirable during colder times of the year.

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…and an equivalent amount of potting soil

Finally I added the ingredient that makes up 50% of my mix: pumice. Pumice is lightweight volcanic rock that, for horticultural use, is crushed or ground into small particles. From what I’ve gathered, pumice is primarily available in the Western U.S. In some locations, pumice is sold in bulk in garden centers or rock yards. Where I live, the cheapest source of pumice is a product called Dry Stall, sold in feed stores as horse bedding material. I get mine at Higby’s Country Feed in Dixon, CA for $9.99 for a 40 pound bag.

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Pumice sold in feed stores under the brand name Dry Stall

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Dry Stall is the perfect size for my purpose

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Pumice added to coir and potting soil…

…and mixed in

The end result is a very loose, airy mix that drains quickly

If you can’t find pumice, there are a number of substitutes that work just as well:

  • perlite or vermiculite (both are sold just about anywhere although finding larger, economically priced bags may not always be easy; check larger nurseries—they may sell you perlite or vermiculite at cost)
  • scoria (small, crushed lava rock)
  • gravel (the smallest size you can find)
  • decomposed granite
  • calcined clay (often sold as cat litter; just make sure you get the right product—you don’t want to get something that turns to mush or has added fragrances or disinfectants)
  • coarse diatomaceous earth (sold in the U.S. by Napa Auto Parts as multi-purpose absorbent; be sure to follow all precautions, such as wearing a respirator if so advised)

You can vary the amount of each of the three main ingredients to create a mix that drains even faster (for example, for extremely xeric cacti) or that holds water longer (for example, for plants from humid environments that like more moisture). You can even add slow-release fertilizer for an even more complete mix.

You are the master of your soil and have ultimate control.

Doesn’t that feel good?


  1. Excellent timing -- I have some cactus that need to be potted! A couple of comments...

    - I can confirm that pumice is not readily available in St. Louis. I've never seen it anywhere. Perlite is what I can find here.

    - diatomaceous earth is somewhat dangerous in that the dust should *not* be breathed. Isn't it too fine for the mix?

    - Why not use sand in the mix?

    - I was going to ask how you found bagged potting mix that didn't contain peat, but then realized you said potting *soil*.

    Great post!

  2. Alan, all excellent points. It's great to hear from gardeners in other parts of the country to find out what their experience with these ingredients is.

    The Napa Auto Parts oil absorbent is actually very coarse but precautions should still be taken. I'll add a note to that effect.

    Sand stays moist much longer than people think and can contribute to rot, especially in the winter when it's colder and plants don't consume as much water. Very coarse sand would be OK, but all I ever see around here is the find playground sand. That's a definite no-no.

    Many bagged potting mixes sold here (especially the cheap ones) actually don't contain peat. Mostly it's "composted forest products." Peat is typically found in more expensive specialty mixes. I guess that's another regional difference.

    There's a lot of information on succulent soil mixes in the various gardening forums, and the consensus is that as long as your drainage component (pumice, perlite, gravel, etc.) is at least 50% of the mix, you're OK.

  3. Interesting mix Gerhard, and a very good one too! Ticks all the boxes to promote healthy succulent growth. Pumice is alot more difficult to get hold of here so I use Perlite most of the time.

    I agree that everyone has their own individual take on the ideal mix (master of your soil as you've said) :)

    Speaking of vermiculite I find that it holds on to more moisture than others. Perlite is much better for drainage and circulation.

  4. Great post Gerhard! Sounds like a good mix. Ok so this is what I do. When I first started and had to put the 4 tiered cement block planter around my whole back fence I needed a lot of dirt. I contacted a rock and gravel company and ordered a bunch of their highest quality dirt/potting mix. We tossed it in planted my little plants then put a layer of yellow rock over the top. I think because my planters are so high it worked. My succulents are huge, over the fence. Then when it came to do my front planters I had a much smaller area. I had learned more and found good deals on the palm/cactus mix and used that to mix with (some) of the regular dirt I left. They are doing well. Stan and my son just finished the planter on the other side of the front of my house. This time I wanted to be even smarter and thriftier but I could be in trouble. We will see. First of all I looked at Debra's books and looked at soil mixtures. I think I really only payed the most attention to one of them because now when I look at the other she says (what you say) that in colder climates your mixture should have less peat. Wellllll, I did go and get 4 huge 40 lb bags of Dry Stall at a Tack and Feed store here in Roseville. But the potting mix I found a great deal on was a large Supersoil variety that has compost and PEAT. Darn! Now we did not use all of our Dry Stall but I have already planted quite a few plants. I wonder if I just add more Dry Stall all around them if I'll be ok. I don't want to dig up the plants and shock them anymore than they already are. Geez!

  5. Candy, you should be fine because you mixed in so much pumice. It's not like Supersoil is all peat, it's just a part of it. Most of it is your run-of-the-mill "processed forest product," which is fairly fast draining (that's why they add peat in the first place). You can always put some more pumice on top to keep the crown of the plants relatively dry.

  6. Yea! Good to hear. I did add another 20 pounds of dry stall. We did not add all 4 bags and I still have 1 bag left. I have been having so much fun planting this planter I did not take pictures. But I will take after pics. You should have seen me yesterday and today. So sweaty and almost completely covered in dirt that stuck to me. In my shoes and gloves. So fun, felt like a little kid.

  7. Another reason to use coir instead of peat: coir is a renewable resource; peat is not. It takes hundreds of years for a peat bog to produce that layer of semi-decomposed material that is used. Coir was actually a waste product from the production of copra and coco fiber, the bits that are too short to use.

    I have a dozen ittybitty cacti and other succulents, but my main growing interest is miniature roses. I struggled for years to find/make a potting mix that worked and finally found that two parts Supersoil and one part coir is perfect.

    I use Supersoil because it is the only commercial potting mix, at least that I have been able to find, that does not have perlite, which I hate. (It floats to the surface and turns such an ugly dirty color.)

  8. Gerhard,
    As many of your subscribers have noted, Pumice is almost impossible to find in various parts of the country. Its is no where to be found in South Texas, even in the larger metropolis of Houston or San Antonio. I have found it at, and they offer free shipping. I have purchased the smaller granules and the powder.
    Hope it helps you and others.

    1. Carl, thank you so much for this useful information! I'm sure folks will appreciate it.

  9. Thank you for this great article - very helpful! I'm working on a mix for aloe and jade plants, grown indoors in pots. I currently have coir and clay cat litter on hand. How important is the soil component? And are the peat-less varieties usually labeled as potting soil or potting mix? Do you think a 1:1 mix of coir and litter would be sufficient? Thank you.

    1. Glad to hear you found this post interesting.

      A soil-less mix should work as long as you fertilize the plants periodically because coir and calcined clay don't contain any nutrients. Also, you will need to water much more frequently because the mix won't retain much water. Personally, I would add at least some soil.

      Each bag of potting soil will list the ingredients so check before buying. Peat is soooo hard to rehydrate once it's completely dry.

  10. I have been getting different ingredients together to make my own mix.
    I picked up 3 bricks of coco coir, some unfragrant cat litter, and I have about half a bag of miracle gro succulent mix... WHICH I HATE so to use it up I wanted to add the above ingredients.
    When I'm done with the miracle gro I will be using kelloggs native plant soil.

    It's been raining like crazy in central coast CA (pismo beach) so I definitely need the drainage.

    Please let me know if I'm missing anything before actually transplanting.

    I've really enjoyed your posts.

    1. I think you have a good mix there PROVIDED the cat litter is pure calcined clay without any additives. I know some cat litter swells up as it absorbs liquids; you don't want that.

      Let me know how it goes!

  11. Hi Gerhard.. can you tell me what damage added deodorizer in kitty litter can do to plants. I purchased some amazing jitty litter yesterday. But it does say odour controlled.. I tried to look fir anything that mentioned not to use.. but found nothing. If I were to wash it first woykd that work?
    Thank you from Australia. 😉

  12. Hi Gerhard.. I purchased an amazing kitty litter non clumping product and was wondering what damage thecodour control ingredient could do.
    Thank you

    1. This is a really good question. I honestly don't know. What you find out what the ingredients are?

  13. I use the MG succulent and cati mix soil, but read in a book from library to add some DE in it. So I went to Auto Zone and bought a bag of oil dry, DE. I will be mixing some in with the soil. Will this be a good mixture for my succulents?

  14. I use Miricle Grow cati and succulent mix. I had a book from library that said to mix some diatometris earth in with this soil to make it more gritty. So went to Auto Zone and bought a bag of DE. Plan on putting some in with the soil. Is this a good idea? Will the DE hurt my plants in anyway? I read it has minerals in it and also protects agaisn't insects.

  15. Has anyone tried using Fuller's Earth mixed with potting soil? I bought chemical clay cat litter and contents is listed as only one single ingredient: Fuller's Earth...clay.

  16. What size pumice is best for use in succulent soil. I am new to this produce and live in zone 8, near coastal South Carolina. HUMID and hot, then cold and damp, then drought and continuous rain. We just never know! I keep plants mostly on covered porches or in a greenhouse when night temps drop to low 40s. I see different sizes of pumice available from different sources. Hoping to finally create a good mix for my growing retirement hobby! Thanks for any advice.

  17. What size pumice is best? Several sizes available on different sites. I live in zone 8, coastal South Carolina and trying to create a good mix for succulents that will be kept mostly under porches and in greenhouse during colder weather. Thanks for any advice!

    1. Hi Jeanne, here in Northern California pumice is only available in one size, maybe 1/8"?

      If you have a choice of sizes, I'd get the smallest size. Some people I know use red lava fines--basically the dust that's left over from larger sizes. I don't think that the exact size matters all that much.


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