It is quite sterile. To address this, people who grow their plants in completely organic mixes such as these usually fertilize them very weakly every time they water.

I don't see how anyone can grow in straight perlite. It has no weight, and can't hold structure. If you place a plant in it, it will just tip over to one side; Also, it would just float away when you water.

Straight pumice, perhaps? If I remember correctly in an older thread, it's for growing Echeverias (specifically echies, because I never been able to keep leafy echies alive before) in tropical climate with high humidity. I usually add perhaps 1 part organics to 5 parts inorganics or more, depending on the plants.

Once the roots grow into perlite, it's just a block. Not much of a problem for plants with a low center of gravity.

And even if I'm growing annuals in containers, I'm fertigated them regularly and putting CRF in the medium. You can't rely on the decomposition of organic matter to provide you with the needed nutrients in a container like you can in the ground.

Ok, thank you all for your replies! Not arguing with anyone here, because you are raising beautiful, healthy succulents. I still wonder: isn't there more to plant health than the usual NPK? Maybe those nutrients are sufficient in whatever cactus mix is used.

When I repot using a fresh batch of cactus mix, I want to mix in a dash of soil from the rose garden or compost heap.

Nil--what is CRF?

Any container plant will eventually run out of nutrients, regardless of the soil type. Perlite and grit just have low CEC, which means they can't hold as much nutrients as say Turface or peat.

This is why more frequent fertilization at lower concentration is used - otherwise it would just be wasteful.

I have many rooted cuttings in pure perlite. As Nil says, after the roots colonize the pot, the perlite stays as one whole mass and the plant is held in place.

NPK are not the only nutrients required. There are a whole host of micronutrients as well.

socks

Using garden soil or compost in containers isn't that good. In ground - garden beds yes, but containers need good drainage so do not clog up one or few small drainage holes.

Succulents, in their natural habitat, grow mostly in very lean and gravely soils, that doesn't have any compost. My plants grow in mix of grit+perlite+turface and I didn't even fertilize for past 3-4 years (since I have almost all of them). Not saying they shouldn't get some ferts, but don't over-love them. Many ppl do. See posts by Kevin - ewwmayo; he has quite controlled growing conditions as light, temps and ferts go and his plants are show-worthy. He grows in a mix just about same as mine.

Sometimes less is more :)