As a recently amped up succulent gardener, I should begin this reply by saying that I started off on a bad note!!! Rotted the roots of everything I potted up at first, because I didn't quite understand the true meaning of "free draining" soil/potting mix..... that being said, I have some priceless advice to offer in that department, as I now own shelves and shelves, packed with THRIVING succulents.. Not SUFFERING! And I even managed to "re-root" most of the ones I tortured half to death in the beginning.....
I tried sand.... I mixed it with soil and perlite and all I got was something along the lines of concrete... concrete that looooooved holding water forever no less... I tried a bunch of things, but my plants kept going down hill..... it wasn't until I picked up a couple 40 lb. bags of this mysterious "gran-I-grit" substance I'd been seeing so much hub-ub about in the forums, that things started taking turn for the better.... and booooy is it better!!! The plants that I thought were goners just 2 weeks ago, with virtually NO ROOTS left on em, and a generally horrid overall look, now have roots out the Bing bang, and gorgeous, strong, healthy new growth all over the place...
Here in TN, I was able to buy (real cheap) 2 grades, 1 they call "STARTER grade Gran-I-Grit", which is like a very coarse grade sand/gravel, and the other they call "GROWER grade Gran-I-Grit" which is coarser and works along the lines as the "small rock gravel" component you need in your succulent mix... I mix a third regular potting soil, and a third of each of those, (oh and a couple handfuls of perlite to lighten it up) and that's where the magic happens apparently! THAT is the meaning of free draining, and THAT is a product I would never go without again! I wasn't able to accomplish that with any of the other suggested ingredients I was trying...
I hear that it may only be available in the southern states, but I hope not (for the rest of he world's sake), and deinitely don't quote me on it... just something I read, and hopefully not the truth! This product may also be sold as "decomposed granite" I believe..... Do yourself a favor, save yourself alotta headache and trouble, and pick some up, BEFORE you begin potting up succulents! Your plants will thank you and reward you!
The premaid succulent mixes you buy in the stores, DO NOT provide adequate drainage... Miracle Grow Cacti & Citrus soil was responsible for many of my plants issues in the beginning, and from what I hear, they're pretty much all like that..... So that's a wrap anyways... Start off with a free draining soil, that only contains 1/3 to 50% organic matter, and the rest GRAN-I-GRIT and chances are, your experience with succulents will be leaps and bounds better this time around!
-Erika