soil

[Bob Sobelman]

what soil mix for ariocarpus?

[Peter]

Some say that incorporating small limestone aggregate in a J.I. compost is the best method, however it's not too easy to get hold of. Personally, I have found my standard J.I. no 3/alpine grit and cat litter to be just fine (1:1: just a little cat litter).

[Eric Williams]

Hi Bob, you will have a different mix from every reply lol. This is mine given to me a few years ago by an exellent grower. An alkaline mix, 3heavy clay loam,5 coarse grits (1to6mm) or3 grit& 2 tesco finest, 2 limestone chippings ( 4 mm). This mix has given me exellent results over the years. Another tip given to me by Rene Giesler, was to have a shelf as close to the glass as practible. My plants are inches from the glass and in very good health indeed. Cheers ps will try to upload some pics if I can soon.

[Bob Sobelman]

thanks eric. this is what I read. and they also said no peat moss in the soil.

[PeterW]

There are as many favourite mixes as there are growers. For all my Mexican desert cacti I use a broadly mineral mix with just a little organic - 2 measures topsoil, 1 measure wormcasts, 5 measures coarse grit, 2 measures crushed limestone, half measure kelp. Other folks will surely say some of that is BS, but my guys seem to do well on it (but everyone says that).

[FaeLLe]

I grow my Ariocarpus in a pure mineral mix - only akadam and pumice (1:1 ratio).

Personally and based on industry articles I have read adding limestone seems to be hogwash? Just because the plant grows in a location with limestone rocks does not mean adding it there is ideal. Sometimes they grow better without it (the limestone presence in the environment could be deteriorating).

[Terry S.]

I have heard growers tell how their Mexican cacti have improved considerably after being repotted in a mix with limestone chippings. My theory on this is that the plants have been improved simply because they have had new soil! I remember a TV programme within the last year where the pH of soil overtopping limestone was measured and shown to be acidic because of vegetable matter breaking down and rain being on the acid side because of dissolved carbon dioxide.

The amount of calcium leached from any limestone in the compost will depend upon the fineness to which the limestone is ground. The John Innes formula required finely-ground limestone to counteract the peat in the compost and bring it back to neutrality. Ground limestone has a high surface/mass ratio from which calcium will be leached at a significant level. However limestone chippings have a low surface/mass ration and would leach minimal amounts of calcium. I would never add limestone chippings to a compost but if you do, it probably has very little effect apart from helping drainage.

[Phil_SK]

Cacti are slow growing. In 'good' soils, they would be swamped by other vegetation. It might be that they tolerate alkaline or calcium rich soils because little else can grow there, so there is less competition for light and water.

[daniel82]

Phil beat me to it. I was going add that I had heard the idea that these species grow in the limestone soils in the wild because they tolerate rather than need it, they avoid competition by doing so.

[Eric Williams]

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Hi Bob, these seedlings are only 5-6 year old. the split pot seedling was only repotted in the above mix last year. My Lophs. love it too LoL Cheers