A Gardeners Forum Forums Gardening Reference Gardening in 2006 Why do Cacti like Charcoal?

Why is it that a recommended potting mixture for Cacti and succulents includes Charcoal? just a question out of curiosity...

I've never heard of one that does, I've never used it, and I've got some lovely plants, so I think it's optional. Charcoal absorbs impurities (whatever that might mean to a plant) which is why it's used in fish tank filters and pumped into the stomachs of certain overdose victims in emergency rooms. If it's coarse enough, it could act like drainage material in cactus soil. Cacti and succs also need a lot of trace elements to do really well, maybe charcoal provides something. I use a diluted hydroponic fertilizer that provides everything. That's all I know.

Cacti and other succulents have shallow spreading root system. As far as I know, charcoal is used to line the bottom of a [shallow] container before adding the cactus potting mix, but not in the potting mix itself.

Some cacti have tap roots and a lot of my aloe have extensive, deep root systems, but that has nothing to do with charcoal. Huangrabarguar, where did you hear this? I'm curious now, too.

'The Complete Book of Houseplants and Indoor gardening' - "succulents, on the other hand, require two parts sand and one part broken lump of charcoal added to the basic mixture."

'The Houseplant Expert' - "Good drainage is essential. Choose a container with holes in the base, or add a thick layer of charcoal."

The second i'm guessing is simply because of drainage reasons, but why charcoal in particular? Usually they just say broken crockery or stone...

Ooh, and margaret e. pell, could you look here http://www.thegardenhelper.com/ubb/ultimatebb.php/topic/15/2902.html and see what you think i should do about my Fatsia? You have a good reputation for "knowing your plants" and no-one else has commented... Cheers!