Should I use charcoal with my mammillaria?

[ecruteak]

Hi guys =)

I have a couple pots of mammillaria right now, previously I was told that I should put charcoal in the bottom of their small pots. The pieces of charcoal are in chunks.

Should I keep the charcoal in the pots, or was that advice bogus and I should remove it?

Thank you =)

[george76904]

Is it just for drainage or are you using it as a soil addative? What kind of charcoal?

[ecruteak]

It's not mixed in with the soil, it's just a layer at the bottom, so I don't think it's... for the purposes of the soil itself. ^^;;

I'm not 100% sure what sort of charcoal it is, my friend passed it to me, her mother uses that kind of charcoal for their orchid plants.

[DaveW]

Charcoal is supposed to be a soil sweetener, but some charcoal sold for barbeques is coated with inflammable fluid to make it light easily, therefore don't use that, preferably use horticultural charcoal. However whether there is any real value in using it in pots is debatable.

See:-

http://www.orchids-world.com/potting/charcoal.html" onclick="window.open(this.href);return false;

http://healingtools.tripod.com/char_gard.html" onclick="window.open(this.href);return false;

However others disagree:-

http://www.gardeningoncloud9.com/200901 ... gardening/" onclick="window.open(this.href);return false;

http://www.gardeningoncloud9.com/200901 ... gardening/" onclick="window.open(this.href);return false;

I have used Orchid compost (mainly sphagnum moss and coconut charcoal) as one of the ingredients of my potting mix for epiphytic cacti since many grow in moss on trees in habitat. The charcoal in it is burnt coconut shell and is very hard, rather like black glass in fact. Whether it serves any useful purpose I do not know, but orchid growers seem to favour it,

http://www.bakularangnusantara.com/Coco ... rcoal.html" onclick="window.open(this.href);return false;

[iann]

A layer of charcoal in the bottom of the pot is worse than useless. There *might* be a case for mixing a small amount of charcoal into the soil. I don't and my Mammillarias seem fine:

albicans-0817.jpg (77.29 KiB) Viewed 833 times

[Pushrestart]

Charcoal in the mix shouldnt be a problem so long as its horticultural charcoal and you recognize the porosity. I've added a bit to my mixes.
What was the reasoning behind putting horticultural charcoal at the bottom, aeration?