As a general rule, with the right culture, you can grow plants in about any medium (including orchids in chopped rubber tires). You may have to adjust fertilizer application and watering but...the media is just there to anchor the plants and absorb water and minerals, and as long as they can do that...good.
That's why I have my adeniums with almost no organic matter, because the rains come and come and come during the growing season.

I'm using basically Al's Gritty mix (turface, bark, granite chips). I don't recall if I added a little bit of peat or not.

I tried gritty mix with Adeniums. During weather in the low 40F range, they thrived if under shelter. But just one good soaking in gritty mix was all it took to completely wipe out all my Adeniums. So for sure gritty is not a good soil to be do watering experiments on Adeniums in the cold.

Well, just general Adeniums hate the cold. We all know that ;) Mine have survived New Oregon (NW Arkansas) where it rains for 4 days at a time, and/or dumps 10 inches overnight. If it looks too wet and too cold, then they come in.

They've tolerated overly extensive rains during growing season, and no rot, but some unhappiness over the 5th day of down pours in midsummer.

One good soaking in 40f in any soil is a no no I use turface only and have no problems I water and feed ever week but all mine are in greenhouse and never go below 60f. I tried gritty mix and I can see no differents

roger

I think that it is great to push the limits as an experiment, but when we know the optimal growing temps of the Adeniums. Why be surprised that they do not survive in 40F and while receiving frequent watering? It is surely away to lose any specimen that you may truly like.

@rcharles I am not tempted to repeat that experiment with an Adenium. But I know with many succulents that are prone to root rot in the cold and wet that pumice alone helps more of them to survive in that condition. Many of my Euphorbias rot quickly in gritty mix if they get continuous rain in Winter. The same Euphorbias seem to survive if left in pumice. Adeniums are just too sensitive and probably there is not a way to win that battle using soil, but I think pumice would still stand a better chance of letting the plant survive an accidental watering in the cold.

Yes, westes. I should have spoke of you initial question what was of the H. Pumice. I use the H. Pumice and actually prefer it over the Turface. I used to use the Turface, but when repotting plants I found that it would work it's way to the bottom of the pots over time through watering and I did not like the result. The Pumice with it's surface area and shape does not allow it to become closely knitted together. The air spaces between each particle is larger. I think with the Gritty mix if it has any fibre in the mix which mine does it would allow it to hold moisture too long in cold/wet conditions.

I was thinking that you where going to use your Adeniums and I know I would hate to lose any of mine.

Stupid question (and may be region specific), but where do you buy pumice ?

I find my Horticulture Pumice at either one of the Nurseries close by (they bring it in if I buy 5 bags) or one of the Local Farm and Feed stores which carries garden supplies.

And being in the center land/heart land/upper south, I've never seen it for sale locally...and shipping is insane (because of weight) at amazon. But, I'll keep my eyes open.

I can't find it locally either, so I started buying from General Pumice Products after reading recommendations on the C&S board. It's pricey but very well screened so not a lot of fines or dust. Shipping is free and they sometimes have holiday promo codes.

@dbarron, I buy my pumice as a stall drying product named "Quick Dry". Very often you will find that pet stores or farm animal supply stores will carry 50 pound bags of various materials to help dry out stalls. You have to inspect the label to know if a particular product is 100% pumice.

Ah hah, just like I buy floor dry product for gritty mix at Auto Zone. Good hint, I'll check the farm suppliers!

I think that it is called Diatomite. Good call, westes. I have had this sitting in my garage for when I was using it in my Hoya mix. Never bothered to check it out. I guess w H. Pumice available to me here. Thanks.

@rcharles_gw Diatomite is similar but I think a major difference is diatomite will crumble into a powder and lose structure. A good pumice is really a strong rock that does not degrade easily and helps maintain structure of the soil. I would look for pumice if you can find it.

The product that I get sold as Horticulture Pumice is quite different in that it is very hard and slightly larger particles size than that of the Diatomite sold here. A difference between the Raw Diatomite and/or the Calcined Diatomite.

westes Zone 9a California SF Bay

Where did you purchased " Quick Dry" ?

I like to try out on my plants

@Kawagoe I bought Quick Dry from An-Jan Pet Supply. You can find other stores at the manufacturer's site:

http://www.ohkruse.com/stores/

But note that the reseller I buy from is not on Kruse's store list, so apparently they distribute to a larger set of retailers.

I will stop by AnJan today. Thanks

@Kawagoe(Home of SF 49ers Santa Clara CA) Just seeing this old thread. AnJan's pumice supplier changed they pumice that they use for Quick Dry. It used to be 10% fines. Now it is more like 60% fines and totally useless for gardening. I asked the manufacturer about this and they insisted they made no change. I actually believe they received a different product from their pumice mine supplier and they were totally unaware of it, and have no quality control for particle size.

@dbarron How far are you from Idaho? One of the best pumice mines in the country is in Idaho and they have a WIDE selection of carefully screened pumice. Expect to pay about $25 per 50-pound bag of pumice, and about $30 to ship it. While it is not cheap, the fact that they screen and wash the pumice saves you extraordinary amounts of time. You can experiment with particles ranging from sand size (#7), to 1/8 inch (#8), to more traditional gritty mix material that is 3/16" to 1/4". I like to experiment with sand size particles in soil for plants that like a moister well-drained soil, like Aeonium. I use larger particles for normal succulents. I have even been experimenting with using huge 3/8" pure pumice with some caudex plants and Euphorbia.