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Use of coir in cactus mix

San Dimas, CA

I keep reading about the advantages of using coir (coconut fiber) as a replacement to peat when creating a cactus mix. I cannot find coir locally (it is sold as a compressed brick) but I do see coconut fiber liners which are used for hanging baskets. I was thinking of just buying a couple of these liners, mashing them up, and using them in my cactus mix - will this work?

Bay City, MI(Zone 6a)

What are the advantages you're reading about? The most significant advantage is coir is easier to rewet after moisture levels slip much below 30%, and that really much of an advantage because most good cacti mixes have very little coir OR peat because the small particle size of either/both supports too much water retention.

What I use for cacti & succulents:


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San Dimas, CA

Thanks for the response. I read that coir was better than for the reasons you stated. Also coir takes longer to decompose than peat, and is PH neutral rather than acidic like peat. I also read most commercial cactus mix isn't the best for the plants. I would like to know what you use in your mix? Your plants appear to be doing quite well.

Bay City, MI(Zone 6a)

Peat and coir break down at about the same rate, with peat getting a slight nod as slightly more stable. Their water retention curves are very similar. Neutral pH isn't something you would consider desirable for container media. Where a pH of 6.2 might be considered ideal for mineral soils (gardens), a full point lower, 5.2, is closer to ideal for container media, so using large fractions of coir in container media precludes the use of dolomite as a liming agent, lest you end up with a pH so high it renders many or most of the micro-nutrients unavailable. Coir also has a very high K content, which needs to be considered and allowed for in your fertilizer regimen or the excess K can cause problems with the uptake of P, Ca, or Z.

I use a mix of

1 part screened Turface MVP
1 part screened pine or fir bark
1 part grower grit (crushed granite) or #2 cherrystone (quartzite)

It's the most productive soil I've ever grown in, as well as the easiest and most forgiving. I have (literally) hundreds of long term planting in the soil pictured. Read more about it and learn why, here:


Everett, WA(Zone 8a)

Hmm! I see from Google that "#2 traction grit" is called 3/16", or almost 5 mm. Pretty coarse! Nice.

(I'm going to add that to my litany of "do you have any ..." when I go shopping for affordab le soil amendments.
I've found crushed rock in semi-random sizes, and "#2 chicken grit - crushed granite". I would have said the #2 chicken grit was closer to 1/8" or 3 mm.

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