Epiphytes vs. desert varieties

fanaticactus · Post by **fanaticactus** » Wed Oct 28, 2009 11:09 pm

I remember reading that desert cacti like a neutral to slightly alkaline soil; they recommend putting some bone meal & a bit of lime in the soil mix to keep it from going too acid. On the other hand, epiphytes love a more acid soil. I notice that prepared commercial 'cactus soil' mixes do not list their contents in detail. Incidentally, I've come to rather like Schultz's & Miracle-Gro's; but, I will begin to use the mixture described in "Growing Cacti" on this site next Spring. My question is, do the prepared commercial mixes normally include some lime? If so, should they NOT be used for epiphytes?

iann · Post by **iann** » Wed Oct 28, 2009 11:32 pm

The definitions are too simplistic. On average, plants from drier climates are more likely to be found on alkaline soils, but that's just an average. There are desert cacti found on everything from pure limestone to quite acidic soils. Obviously epiphytic cacti are not really found on soil as such, but what you might call wet-climate tropical cacti can be found on anything from pure organic soil, obviously acidic, to limestone pavements. True epiphytic plants are not usually tolerant of alkaline conditions because they receive rainwater directly and anything around the roots is likely to be organic rather than rock.

Commercial soil mixes will be some combination of peat and "forest products" such as sawdust and bark, or occasionally coir. They will include sufficient limestone dust to bring the pH near neutral, typically around 6-7. The exception would be ericaceous soils intended for lime-hating plants. These will not have lime and may well include sulphur to make the pH even more acidic than the natural ingredients. I don't know enough about the epiphytic cacti to tell you which soil you should use, but I know people who use mixes with plenty of peat.

fanaticactus · Post by **fanaticactus** » Thu Oct 29, 2009 12:09 am

Thank you for this info. It provides some useful insights I can use when preparing my soils for the next growing year. (Oh, if only I lived where I didn't have to worry about temperatures below freezing!)

Harriet · Post by **Harriet** » Thu Oct 29, 2009 12:08 pm

I'm still so new at this that you need to take my advice with a large grain of salt, but... I have been experimenting with a mix of Miracle Grow Cactus potting mix, perlite and "orchid bark" (wood chips) for my epis. (Equal parts potting soil and bark and a healthy dose of pearlite.) I haven't killed anything yet, and they seem to be taking root and sending out shoots. Epis grow on trees and rocks and things, not in the soil, so I figure the less dirt to hold water next to the roots the better...

Also, If you add a lot of the bark to the mix you may not need the pearlite...

fanaticactus · Post by **fanaticactus** » Thu Oct 29, 2009 2:33 pm

Hi Harriet, Thanks for your info. Except for the pearlite (which I find often floats annoyingly on top) I have those ingredients & will definitely try them. In fact, I bought some rooted & unrooted cuttings & had them for months in soil that I guess was too dense. They didn't do anything; in fact, a couple just gave up entirely. This summer, I divided the cuttings among three pots with cactus soil & a lot of coarse sand I bought at the hardware store. Lo and behold, they started to put out shoots like crazy & look much healthier. I'm still waiting for the first blooms, tho! Good luck with your epis & thanks again for your answer....Dave (fanaticactus)

Harriet · Post by **Harriet** » Thu Oct 29, 2009 2:37 pm

Perlite is pretty pesky. I'm thinking about using coir instead, but I haven't taken that step yet...