I can't get pumice cheaply here so I use Poultry Grit sold in feed stores. The fine would be what I use on tiny plants and the larger size for bigger plants. I have used regular potting soll with good results for most of my Sans. Some swear by gritting mixes. Since switching my Sans have been growing much better.

I don't think the coarse material would be appropriate in a conventional container medium due to the significant size disparity between the perlite and the rest of the mix materials. The finer material looks like it might be propagation grade. I think, unless you're growing epiphytes, the finer material will serve you much better, and that would be especially true if pine bark represents a noteworthy fraction of the mix.

Perlite's primary function is acting like a ballast, which simply means it displaces a volume of soil particles that would otherwise be filled with water or air. That means it's primary value would not be aeration, but a reduction in water retention, which also means it's only beneficial when it occurs in the lower reaches of most plantings - like maybe the bottom 6" of the pot. In fact, if you have a jar full of sphagnum peat and you start adding perlite to the jar, aeration goes down and continues to decrease until so much perlite has been added there is no longer enough fine material to fill the spaces between the perlite particles. Only then, does perlite increase aeration.

Al

Stush, I too find poultry grit is a lot cheaper than pumice! It is also a bit easier to find for me than pumice. What would be your ratio of media to potting soil?

Tapla, I am glad to hear that the finer pumice would be more appropriate. When you say: " especially true if pine bark represents a noteworthy fraction of the mix." Are the pine bark you mention to be ideally around 1/4 inch size?

Also it is hard to wrap my mind around the fact that it doesn't increase drainage. It's just that it is ingrained in my head. So if perlite takes up space in a pot, it is decreasing the amount of water the media can hold in the pot unless you put a lot of it in. Man I have to copy this and reread again and again!

This might be helpful. Start reading at "Media Fundamentals" through figure 2 for a visual explanation. More later. I had a long post written up and I opened a new window and lost it. Grrrr!

Al

I have been having very high results with no grit at all in my Sans mixes. Maybe a little perlite to lighten up a little. With Aloes and Agave, I use maybe 25% gritt. With the larger ones, I use almost anything. Special plants I add a little alfalfa meal to the mix which simulates double the growth.

I grow mine outside during the summer months but not in the ground. Maybe in the long run gritty mix may be good but so far (3 years) mine are doing good in their new mix of almost pure compost. When the weather gets hot, Sans love more moisture. In fact my Bantal's Sensation sits in water for many months of summer. In the fall when temps start to fall, they must be kept dry. So at that time a grit mix is good.

That's interesting Stush. I have put a couple of my Sans outdoors. Mostly because I didn't like them for one reason or another. So it's an experiment for me to see how they grow. I'm just interested in the pups they grow and will keep them and propagate parts of the main plant or throw them away. I probably should repot the ones I put outside as they get drier outside with the wind than they would like to be. I have them in a sheltered location.

Tapla, I am still studying. Slow learner here.

So I've been studying the link you sent Tapla. Thank you. I have a lot of questions. I think it best to post them on the Container Gardening Forum. Just have to figure out which questions to begin with!