OK @tarev and @Kaktus I am just wondering which succulents that you might consider to work well with the temperatures in the 90+ F range and the high humidity that
we often get in Houston, TX or in Indonesia, or even in San Joaquin Valley CA

I am curious to hear what recommendations people may have on this subject. I did adjust the subject line to indicate what the thread is about, with the hopes of drawing in more eyes and more participation. I hope that's okay, Will.

Also, I think maybe @purpleinopp may have some useful suggestions for you. Anyone else with experience, please speak up!

Don't know where to start, not really to share experiences, but more on sharing observations and experiments that I've done so far.
I started playing with succulents only in the past 2 years, but quite familiar in growing plants like flowers or fruits, etc.
In Indonesia everything can grow well, the main difference will be high land and low land, they will have around 10 degree celcius difference. Since you mentioned 90+F, then it will be the low land like Jakarta where I live.

Most of the succulents like Echinopsis, opuntias, euphorbias, aloes, sanse, agave, gymnos, adeniums etc. can grow pretty well in here. ( need to match on the zoning below), surprisingly Huernias growing well also.

So far I failed in almost all succulents that have thick/watery leaves like echeverias, sedums and crassulas, types of haworthias with thick skin can grow well, but not for haworthia with thinner skin.

I classified the place for keeping my succulents into 5 areas:
A. Shady, bright, no direct sunlight at all
B. Hot and bright , no direct sunlight
C. Hot and bright , 2 hours of morning direct sunlight
D. Hot and bright , 4 to 5 hours of direct sunlight
E. Hot and bright , 4 to 5 hours of screened direct sunlight ( with plastic and/or mosquito net)

Last year I grew everything in zone A and they did not performed well, this year I moved everything to zone B to E, every now and then I move them within the zones to find the correct spot for them, it seems like zone B and C works best for most of the succulents.

Personally I like to have plants that have different stressed color like brown and purple, so I like to explore the stress level of the plant to get the color that I want, I may kill some of them along the way, but since I only focus on cheap succulents ( I have set up the maximum price per cactus that I purchased), then those are still within my budget.

Since there are no winters in here, I think we will enjoy a long growing season, but the trade-off is our succulents are very difficult to flower, so far mammilarias prolifera, haworthia, stapelia gigantia, huernias, aloes, persian carpets, dorstenia can easily bloom, the rest are quite difficult. Some of the plants grow very fast, I don't know it is normal or not, I'll share some details later to you to see whether it is normal growth or not.

July and August will be the hottest months of the year, and I have started to see some sun burn indication on the plants in my zone C to E.

On top of the climate / sunlight limitation that I mentioned earlier, I think the watering regime, soil fertility may contribute to the growth. And I also believe that I can slowly train some of the plants that currently can not survive, to make them accustomed to our weather.

I am still experimenting on what can grow well and what can not, at a latter stage then I will try to train some plants that I failed before, also as a preparation for me when I bring some plants from other country directly to Indonesia.
They are in my shopping cart now, possibly I will get them this month to test my growing skill :
- haworthia truncatta
- Aloe Christmas
- Haworthia tesselata
- Gasteria Fuji mini


I will share some photos later to give a better picture on what is all about

Will, I think the big trouble you face with trying to learn from people who either live in the tropics or know people growing succulents in the tropics, is what Kaktus already mentions: they have no winters, their plants do not also have to be cold hardy in addition to heat and humidity hardy, which yours have to be because Houston gets just enough of a winter to make that a big deal.

I think Tarev already made a good point in the other thread where this was discussed: you need to have a fast draining and drying mix, and you need to be careful with pot size - overpotting in a humid hot climate on plants that really do not like humidity much, is a killer. Also like Tarev mentioned you need to consider the humidity of the air the plants are exposed to, this is an issue in hot humidity and cold humidity, generally speaking providing good air flow will help, stagnant air is a killer. That is why I would recommend against using plastic sheeting as any kind of sun screen, Kaktus, mosquito netting or actual shade cloth that provides shade but allows plenty of air flow is a much better way of protecting plants from sunlight.

One place to go look for succulents that can take high humidity and heat is to check out what the Thai nurseries are growing and selling, those are good indicators of what easily grows in those conditions, but never forget to ask yourself what the cold hardiness of the plant is, if you do not you may solve your summer heat and humidity issue but only to end up with plants that croak at the first signs of 40F or below nights.

I have little experience with the Echeverias etc, simply because they pretty much tend to be annuals here unless you bring them inside in summer and provide them some alternative source of bright light - you can grow them inside without that but they become etiolated incredibly fast. f you leave them out they tend to croak when it gets hot and dry no matter what you do (leave dry, water, etc.). I have recently read that it is possible to grow Aeoniums here outside as long as you bring them in full shade in summer and essentially do not water them or very very little. I might try some starting this fall and see if I can get them through next summer.

sharing some pictures to show the growth...

The echinopsis is the fastest growth in my collection, pls ignore the dying bearpaw, it is there just to show the size of the pot, you may also zoom and see the beatiful purple color on the baby echinopsis



And below are the favorite color changing of miha, looks like someone paint it purple overnight. Another one is progressing, last month still looks like Anisitsii, now it looks like miha


And I try to keep my expectation low on these 5 miha ( I bought 7, 2 not in the picture), they are seed grown from variegated parents ( 2 have Pink Diamond bloodline) and 3 with aurora bloodline ( the picture of the parents below), Some people said that there are some incidents that extreme environment may trigger the mihas that have variegated gen to show their variegation, crossing fingers I hope this can happen
But this to show that the hot weather in here can trigger the color changes


with the hot weather in here, I think can easily make persian carpet and euphorbia Decaryi change color from green to brown or vice versa in 4 days.

Thank you for the mention, Baja. The weather here is similar to Houston, from what I see on weather reports.

Succulent plants I've had for a long time and are hardy enough to have been outside for years and remain "evergreen", at least when protected from direct rain in a mini garden (see mini garden forum for pics of the entire gardens over the yrs.) An especially hard winter could be a disaster if my only copies of any of these are outside @ the time. And since they've stayed alive for years, they must at least tolerate humidity, dew, and nighttime lows well above 70 for months:
Jade Plant (Crassula ovata)
Ghost Plant (XGraptosedum 'Ghosty')
Silver Squill (Ledebouria socialis)
Living Stones (Lithops)
Striped Inch Plant (Callisia gentlei var. elegans)
Sedeveria (XSedeveria Sorrento™) (and probably other/most Sedeverias)
Sedum (Sedum kimnachii)
Graptosedum (XGraptosedum)
Prickly Pears (Opuntia)

Other hardy plants that I use as part of the ground landscaping. Most of these go dormant over winter, losing the above-ground parts and re-growing from the roots in spring, and I bring at least a few of each inside for winter as backup. Never know which winter is going to be the unusually rough one:
Florist Kalanchoe (Kalanchoe blossfeldiana)
Scarlet Kleinia (Kleinia fulgens)
Devil's Backbone (Euphorbia tithymaloides)
Shrubby Stonecrop (Sedum dendroideum subsp. praealtum)

Plants that I've always brought inside for winter, outside for summer, and have had for years, that grow well:
Lavender Steps (Senecio crassissimus)
Tiger Tooth Aloe (Aloe juvenna)
Pencil Tree (Euphorbia tirucalli)
Christmas Cactus (Schlumbergera truncata)
All Kalanchoes I've had except hildebrandtii and tomentosa, which are in the next category below.
3-4 species of Rhipsalis, including I think baccifera & teres, but they never bloom.
Red Log (Peperomia verticillata)
Blue Senecio (Curio talinoides)
Euphorbia (Euphorbia hypericifolia Diamond Frost®) (I noticed in 1 spot where I put a cutting that it has survived in the ground for the past few yrs, but it is the only one of a larger group that did not survive.)
Wingpod Purslane (Portulaca umbraticola)
Aloe Vera (Aloe vera)
Fianarantsoa Aloe (Aloe bellatula)
Haworthiopsis attenuata var. radula
Gasteria 'Little Warty'
Crown of Thorns (Euphorbia milii)
Various Echeverias.

Plants that I've always brought inside for winter, outside for summer, and have had for years, that are more just stayin' alive but don't seem to grow much. Most of this group has not been repotted for years & these plants are still in old store-bought soil of some type, likely "palm" soil but I don't remember for each pot by now:
Easter Cactus (Hatiora gaertneri)
Starfish Cactus (Ceropegia grandiflora)
Flapjacks (Kalanchoe luciae)
Trailing Jade (Kleinia petraea)
Watch Chain Plant (Crassula muscosa) (Occasional cutting in mini garden will survive, but they tend to die over summer.)
Lifesaver Plant (Ceropegia zebrina subsp. zebrina)
Baby Burro's Tail (Sedum burrito)
Golden Sedum (Sedum adolphi)
Jelly Bean (Sedum x rubrotinctum)
Baby Sunrose (Mesembryanthemum cordifolium 'Variegata')
Aeoniums (Aeonium)
Arizona Ruby Rainbow Hedgehog Cactus (Echinocereus rigidissimus subsp. rubispinus) (Starting to wonder if I should find a spot for this to stay outside all year...?)
Echeveria (Echeveria runyonii 'Topsy Turvy')

As far as soil goes, one mini garden has store-bought, "palm" soil, I think. The other has ground dirt.

I've moved most of my non-mini-garden plants over the past few yrs to unglazed clay pots with ground dirt. Not just any dirt, like out in a mowed area, but the better dirt where flower beds are, and from under a brush pile where we put yard trimmings that have leaves until the leaves disappear, then burn the big limbs and let the small twigs slowly decompose. Pretty good dirt under there, and I can replace it as often as I want for free.

It's usually upsetting to some people when I say things like this about ground dirt, but please know, I'm not recommending, just saying what I do. You'll have to do your own experiments to see what works best for you. As a long time serial overwaterer of plants in general, this has helped me tremendously, especially for succulents that bake-dry almost daily. Some might not be growing much, but staying alive is a great step in the right direction after killing so many succulents when I first started buying them and trying to keep them alive in the "store soil" in the original pot or after any kind of repot.

I keep saying "dirt" but I mean gardened-soil. For those who are also outdoor gardeners, you'll know what I mean by the difference between the lifeless stuff baking in the sun in which grass is struggling to grow, vs. the much darker, improved "soil" in a cultivated spot where gardening/mulching/composting has been occurring for at least a few yrs. I have a LOT of potted plants, but this is only because they can't stay alive in the ground outside. If all plants could do that, I'd have maybe a couple hanging pots & that would be all. My true love is ground gardening, but unfortunately or otherwise, I've also fallen in love with so many plants that can't survive out there all year. If you have even a glancing interest in soil microbiology or think you might if you had more plain-language info, this talk by Dr. Elaine Ingham is, IMVHO, the gold standard for a good place to start: https://www.youtube.com/watch?...

Each of our growing areas have such micro climates. My area for one goes into a long hot and very dry condition for 6 to 7 months. Late Fall to early Spring is our rainy mild winter period. But that being said, Jan and Feb tests a lot of the endurance of my succulents from cold overnights.

So far on my side, succulents under the Crassula group handles the extremes of our weather here.

Echeverias do quite well here provided I move them in part sun/shade when the long hot amd dry days are here.

Sempervivums sadly does not grow so well here. They can easily get pan fried by our heat, or bolt quickly. They quickly go dormant once temps goes into the high 90's. Our summers are dry, zero rainfall so humidity is just so lousy. Oftentimes, I maybe able to grow them from Fall to early Spring..beyond that they get fried.

Haworthias and Gasterias do well here outdoors year round, but must be positioned in part sun/shade. Morning sun is best. Thankfully my garden has natural cover from the canopy of city trees..but that being said, when temps exceed 95F into triple digits, even the most drought tolerant plant needs to be given good watering at a timely interval. This year has been so dry..so hot, that I even have to move some succulents under the garden umbrella.

Adeniums, Plumerias, Yucca, Beaucarnea recurvata, Cycads endures our triple digit dry weather here very well, provided I also step up watering. Plumerias and Adeniums though are quite cold sensitive, so got to be mindful of overnight temps. Adeniums typically go dormant during the winter season..so when outdoor temps starts to go below 50F it is time for indoor safekeeping. But I still position them by our south facing window, and watering reduced less to none as winter ensues.

There are many types Plumerias, and some needs more humidity and moisture. It has been trial and error for me to find out which cultivar likes my area. I have to admit I got lazy briging it in and out during its winter dormancy period here, plus it got too tall to move, so I just made sure the media is gritty and porous enough and have positioned it in the sunniest side of our garden, so it can get all the sun and heat it loves. Winter is always a critical time so it may suffer from some black tip issues. I just prune those off and allow it to naturally air dry.

Sedums and Senecios can tolerate our conditions here, but they languish during the hot and dry days.

Cooler and dry weather seems to be the preference of most succulents. Less stressful for them heat-wise. By cooler temps, that is in the range of 65F to 85F.

A lot of times, it will require trial and error to find out which succulent will thrive here..each season, every year is different now. So go to be ready to reposition them and adjust watering as needed. For the most part, new plants that I try out, I feel more comfortable when I see their origin is from South Africa. Those varieties ably adjusts and grows well here in my area. I also try not to get new plants in summer. It will be to late for them to adjust to our extreme heat here. Ideally, I try to get cuttings or if I find new ones, I prefer to do that in Spring to allow time for the plants to acclimate.

Aeoniums goes ratty and dormant here during the summer months. They bounce back towards Fall. So I have learned to chop and get cuttings towards Fall.

Euphorbias handles the dry weather here nicely but may get heat stressed so I try to position them in part sun/shade. Always with a gritty, porous media. I also try to bring all the euphorbias indoors during winter. Sometimes I push the envelope as far as I can. If it continues to be dry and cool outdoors down to 40F, I may let them stay outside a bit longer. If some I cannot bring indoors during winter, then I will just position them as close to the house as possible. That way they get some heat being released by the house or some protection from the cold air depending where it blows. It will be in Mother Nature's hands to water them if the rain comes in winter.

At most 30F is still tolerable to most succulents as long as they get to stay dry or dry out as fast as it can.

At 20F range, expect poor to no survival for most succulents.

I grew up for 28 years in a tropical.country and at that time I was more accustomed with tropical.plants. Anyways, now that I know which are succulents or needs better handling as succulents, when I used to visit back home, I try to educate my friends to use gritty material for succulents. The standard soil used there is loam soil, very rich and really good for many tropical.plants. Lately flash flood/excessive rainfall has been occuring and I was told at one time some areas in my home city was flooded for a month. The only inground plant that survived surprisingly were Sansevierias. So the last time I went home, most gardens have Sans as their plant of choice.

It was my mistake here to not consider the temp. I almost killed one container full of Sans, leaving them outdoors in the rain. I forgot to consider winter temps...ooops, so many of them rotted, but I was able to salvage some and it took almost a year to revive them. That was a hard lesson for me...so consider watering and the ambient temperature.

Hope that helps when anyone chooses whichever succulent you want to grow. Good luck!