Bonsai mix for cacti?

[bluecanary]

Has anyone done something like this? This mix I'm thinking of in particular is Hoffman's Bonsai Soil Mix with these ingredients: Haydite (expanded shale), sand pebble, aged pine bark, and Turface. I would use a sieve to sift away the finer particles. Is this suitable for cacti to be placed in?

[DaveW]

A lot of people have been using certain types of baked clay cat litter (Kitty Litter) as an ingredient for cactus mixes for a few years now, make sure you get the correct type though not just any cat litter (see the Bonsai links for guidance). You are also able to get pumice more easily in the USA than we can in the UK. Not sure about pine bark as an ingredient though.

http://www.bcss.org.uk/foruma/viewtopic ... 1&t=162620" onclick="window.open(this.href);return false;

http://www.bonsai4me.co.uk/Basics/Basicscatlitter.htm" onclick="window.open(this.href);return false;

http://www.bonsai4me.co.uk/Basics/Basic ... page3.html" onclick="window.open(this.href);return false;

[AgavaSK]

Hello,

as already written, there are almost as many receptures for cacti soil as there are growers. Bit I don`t think this soil is useful for cacti because it is acidic and it contains pine bark. Well, maybe for Rhipsalis and Hoyas and Epiphyllums in particular percentage....

[iann]

On the whole, ex-plant material is not ideal for potting desert cacti. Small quantities (5%-10%) may be useful for maintaining nutrients, but none is better than too much. Acidity as such isn't a problem for many cactus species (perhaps for some), but organic materials are unstable, hold either too much or too little water, and are good starting places for the pathogens that plague cacti.

Not sure why you'd want to use both Haydite and Turface. People have a habit of overthinking these things and ending up with a dog's breakfast. I'm not sure what sand pebble is.

[bluecanary]

I didn't think it would be the most ideal but I'm still learning about what ingredients are most acceptable to use. I will be looking into pumice and diatomaceous earth/kitty litter as well. Thanks everyone!

[Steve Johnson]

Totally agree with everything Ian says here, and it's beyond me as to why some people "over-engineer" their cactus mixes. Keep it simple -- 1 or 2 ingredients. If you can get pumice, you won't need other minerals like Turface, NAPA 8822, Perlite, etc. Growing in straight pumice is great, although if it dries out too quickly, adding soil for better moisture retention will help. Okay, so there's your 2 ingredients for a good cactus mix. Plant materials in a potting soil may be fine for jungle cacti, but with desert cacti we want it to be as lean as possible. I just found out about this on eBay, and you can find it here:

http://www.ebay.com/itm/ARIZONA-EARTH-N ... 2a50c066e2" onclick="window.open(this.href);return false;

http://www.ebay.com/itm/ARIZONA-EARTH-N ... 2a5107dce7" onclick="window.open(this.href);return false;

The word "organic" gets thrown around loosely, so we need to make a distinction between soils composted with plant materials and mineral soils which haven't been pre-loaded with a bunch of chemical fertilizer. The latter applies to the Arizona Earth Naturals soil, and this may be the most promising thing for desert cactus growers that has come down the pike in quite awhile. Although I haven't had a chance to test it yet, this may be worth at least some experimentation for those of us living in the US. If the experience pans out well as we get some time on it, AEN will deserve further recommendations on the forum.

[iann]

I just found out about this on eBay, and you can find it here:

http://www.ebay.com/itm/ARIZONA-EARTH-N ... 2a50c066e2" onclick="window.open(this.href);return false;

Shipping is a bit steep to the UK

[Steve Johnson]

Okay, I just purchased a quart of the AEN soil for testing purposes. Don't want to steal bluecanary's thunder, so I'll start a new thread with the results of my wet-to-dry test with a 70/30 pumice-soil mix. Give this about 5 weeks or so, and at least it'll be mildly interesting.

[Saxicola]

I agree with Ian and Steve about not getting too complicated. You should ask yourself "what does this ingredient add to a mix and why am I using it?". If you don't have a good answer then don't add it (or do some research). My standard mix is 70-80% pumice and the rest a Coir based potting mix I have ready and free access to. Pumice provides excellent drainage, but is porous so holds some water (which is more desirable than crushed rock without pores). If I had a good soil based mix I'd use that, but Coir works well for me to provide a little more moisture and nutrient holding capacity. Coir is better than peat because it rewets easily when it dries out (peat does not). When using Coir I have no intention of leaving the plant in that mix for years on end. Organic mixes break down and rot over time. You don't want that. I try not to keep it in the same mix more than 2-3 years.

I use 100% pumice for especially rot sensitive plants (like Stapeliads) because I want the maximum aeration and drainage possible while still using a material suitable for growing plants.

I give that as an example of what I do and why. You don't need to do what I do, just make sure you know why you use what you use.

Steve, I look forward to seeing the results!

[bluecanary]

I ended up getting some pumice for some of my cacti to use instead, mixing only a little amount of generic cactus/succulent soil with the majority being pumice stones. They were just repotted today and I look forward to seeing how they do in it. I'll be getting some more soon for the rest of my small collection. Thank you again, everyone.

[andy_e]

If you want more water retention than pure pumice, you'll be better off adding Turface (or calcined DE) rather than commercial cactus mix. You'll have much better air circulation in the root zone and a more stable mix without sacrificing water retention.