Got a Hold of some Decomposed Granite

[Tlaloc]

I tried to sift though the post involving decomposed granite and it proved simply too much to go tough so i was wondering: can decomposed granite be used as a general component to cactus soil to make it drain better? could i use it a general ingredient when trying to make soil leaner and/or better draining? and for that matter could i do the same with crushed lava rock pea gravel or expanded clay? these where the only things i could find for these purposes at the local garden stores.

[Joel143]

Yes you can use decomposed granite. I wouldn't use pea gravel because of its smooth surface. I wish I could find DG small enough to use in my amended soil for my cacti. Right now I use oil absorbent.

[iann]

Lava rock can be good because it is extremely rough, but it depends if you can get it in a suitable grade. I like the expanded clays, they hold the right amount of both water and air. Can you not find pumice where you are?

[Tlaloc]

i can't seem too,and the lava rock comes in big 2 or 3 inch chuncks, but i'm not above putting it in a sac and smashing it with a hammer till i get little rocks. thanks guys, and does smooth=bad with soil ingredients?

[iann]

Smooth rocks hold relatively little water but almost no air. Makes for a very heavy mix that promotes rot if you aren't very careful. Porous, or failing that rough, rocks hold air and make for a much more forgiving soil. I have also noticed that using something like pea gravel as a top dressing, it seems to wick water up when the soil is damp. Sharper grits don't do it.

[Tlaloc]

kay, noted, smooth stones=bad. oh by the way,split rock- grittier or little more soil than lithops?

[iann]

kay, noted, smooth stones=bad. oh by the way,split rock- grittier or little more soil than lithops?

About the same soil, but not really the same treatment otherwise.

[Tlaloc]

okay then. i got another split rock and triple checked it to make sure it's rot free. it jsut has a third pair of leaves, but their pretty much shrivled off already and the rest of the plant seems fine.