Ive seen cacti (opuntia) grown on beaches...and they dont grow much...agaves often look half dead... Think the only plant that does fine is carpobrotus....

Grown on pavements with grass(with mounds of course), away from the sand is a different story..

So, best advice i can give you(if you are using sand) is get to bigger sand...

rina, could one substitute vermiculite for turface in your mix?

asclepiad, my limited experience with gritty mixes indicates that plastic pots work better as the gritty mix dries out so fast the roots desiccate easily.

Sans2014 . That is correct. The mix contains some peat. The mix I use is equal parts grit and peat (or coir with peat, more precisely). My summer is relatively humid and winter is rainy. Plus, those succulents grow in the shade. I might give them more water than average in summer, but I can't control winter rains. The cultivation area is just too big for a shed. Your area may be different and demand an equally different approach.

Rina, i know that Haworthias are cultivated with coarse sand by professionals in my area. From experience, fine sand was less of a success. My beach sand worked equally well as quartz sand, but this may not necessarily be the last word. I have to find more reliable 8nfo on native soil before deciding. Hope to find that soon. This bit of info is mostly overlooked given the availability of commercial mixes.

The culprit is pH. Rina is correct about beach sand only working for limestone loving plants and that most succulents prefer acidic soils. This is especially true for alooids which evolved to live in acidic soils that are low in calcium. Salt isn't the only culprit in beach sand and you'd be better off growing in quartz, which won't make your growing mix alkaline

Sans

I do not use vermiculite at all - it seems to 'collapse' when wet. It's water holding capacity is similar to turface (approx. 52 for turface, 48 for vermiculite - this is from measurements by ewwmayo). I have seen info suggesting whc is as high as 72 for vermiculite - I am not sure which one is more precise. I use ewws info. Ph seems to be more variable for vermiculite, 5 - 7.5, but that is likely in range OK for most succulents.

asclepiad

Some sites mention what kind of substrate plants grow in habitat. Not all, but many. I tried to find a list, but not much luck. As for size of your sand, how small is it - did you try to measure it? Here is photo of size for my typical mix (there is only grit and perlite in this photo):

Rina , it is smaller, between 0.5 and 1 mm. Size varies, and 1mm is the norm. Some locations have more seashells than others, and this may affect success rate when speaking of pH. I had a hard time finding data on native soil just as you had. That is why I experiment.

asclepiad

IMO, that is too small. I prefer not to use anything smaller than 2mm. Mix in the photo above is approx. 4-6mm, and the smaller one I mentioned is approx. 2-4mm. I could add some peat to the smaller mix, but I very seldom do. Adding anything smaller to the bigger mix doesn't seem to be worth it since it would just fall in-between all other particles and settle at the bottom (or even get washed out), or create layers of fine particles and bigger ones.

I had a list of (mostly) cacti that prefer limestone, but can't find it anywhere (just found it, link below)...it was not that extensive anyway. Spanishfly grows cacti, and they are all limestone-lovers. Here is something from Succulent plant page:

..."Some lime-hating succulents e.g. Echevieria and some South American cacti e.g. Echinopsis, Gymnocalycium grow naturally in peaty soils and should not be grown in compost with added lime. On the other hand, some North-American cacti, e.g. white-spined Escobarias, Ariocarpus fissuratus, Lophophora williamsii, seem to prefer limestone soils and a handful of ground dolomite of lime may be added to the potting mix"...

ETA:

here is the list I mentioned...FOUND IT :)

To check for salts, you can use a TDS meter to see how well you have washed off the sand ($4 CAD on Ebay). Since the beach sand is very round and smooth, I don't expect it to be able to hold much salt.

To check for pH, you can similarly use a pH meter ($8 CAD on Ebay). If the mix leechate is too alkaline, I suppose you could get some pH Down (Phosphoric acid) from a hydroponics store ($20 CAD for 500mL - smaller bottles are cheaper). At 80% concentration, just 0.5mL can bring the water pH from 7 to 5.5 for 4L of water. Then you could use that acidified water each time to offset the mix.

I would think that sand and peat moss/coir would be far too water retaining for humid summers and damp winters. Like Rina mentioned, it sounds like the particle size needs to be much larger, especially when using the potting soil components. My opinion is that when using peat moss based soil, a very basic ratio and inexpensive easily available substrate would be at the very least 60% perlite, and perlite holds a fair amount of water compared to something like chicken grit.

What if you go a step up in size and try chicken grit? I'm not understanding why you're sticking with the beach sand with shells.

Jeff, so flint grit is just the thing you recommend? Here is a link: https://keeping-chickens.me.uk/getting-started/grit/

The insoluble part if flint, ofted with added oyster shells for healthy eggs. The oyster part, I understand, has to remain low.

I just mentioned grit because it seems like it would be the next size up from the sand you're using. I haven't used it myself. I'd recommend pumice, especially for Haworthias, but I don't know if that's available or affordable or something you'd want to experiment with. The roots on my Haworthias (Haworthiopsis may be somewhat different, like venosa, etc.) are monsters compared to when I used potting soil and perlite. For Aloes, they grow very extensively. This is with no potting soil, peat moss, coir, etc. It's still a rather strange thing for me, to think the roots love to grow in such an open substrate like that.

Yes, I have seen many websites of growers in Japan. They cultivate their hybrids in what appears a disproportionally large pots for the plant's size. The roots are well out of sight but should not be out of mind... but that necessitates better draining for the larger pot.

asclepiad

I buy chicken grit, but only plain - without any shells added. There is a mix available with shells, and that is good for chickens. Easy to get, inexpensive and literally no waste. I usually rinse since there is always some dust in the bag, but particles are quite uniform in size.