Hi Trace,
I grow bougainvillea in a container, which I got last year. My area is inland, very dry, very hot and what I find is my bougainvillea loves being watered early in the morning. I do not water at the height of the heat and hot sun. It will be its second year with me, so I am hoping my plant has acclimated already to my surroundings and hopefully in time it will try to make those lovely bracts. Plants do need to get established as mentioned already by others above. I do wish I have better humidity conditions here, but such is our location. So even if my bougainvillea is drought tolerant, it really appreciates the watering it gets. I just do an interval, like every two days, and it will also depend on what our temps are like, if it is only up to the high 80's I can do every 3 days, but if it is forecast to be several days of high 90's and higher, I have to do the watering at least every other day. Otherwise the leaves will dry out so fast.
I also grow succulents and other drought tolerant plants but all of them are in containers. As the season change, I move the containers, the more sun loving ones more exposed to the sun, and the less tolerant succulents, are towards the shade. What makes my plants survive especially during our heat waves, is the extra shadow from the canopy of the city trees. If not for that, it will be really hard to grow the plants, succulents or otherwise. If you think about it, in true desert-like areas, there are not much plants there. They just cannot stand the intense heat of the sun, and lack of moisture. I deep water the containers sometimes once a week or in those extremely long heat wave, I find I have to do a mid-week watering. Come fall and winter time, I hardly water, that is the time we have rain here.
I do not know your exact planting conditions, nor what type of soil you have there in your area. You may have to find ways to shade your plants, and maybe add misters around to help with the moisture needs. Drought tolerant plants still need to be deeply watered too especially during the very warm days, but do it early in the morning if you can, or early evening, or whatever is your city's regulation about watering.
Also when heat is so intense, most plants do shutdown, they try to conserve their moisture, so often times the growth of the plant is smaller, and they start dropping some leaves as it redirects moisture to other parts of the plant.
