Well, you're at the 8/9 boundary, same as me, but your climate's significantly different. I don't think the quadrangularis will survive your winters. As I understand it, it's quite frost sensitive. I wouldn't know from experience, as I've never tried to grow it. Alata may do well for you if you provide shelter for it in the winter, in the form of mulch and cover plants to protect it from the cold. I planted one out this past fall, and the growth tips got froze pretty badly but the plant as a whole pulled through fine. Actinia is rated for 9 and warmer, from what I see online, but supposedly can withstand light freezes without much damage.

If my thinking is correct, all three have evolved in warm, humid environments, so your exceedingly dry climate might prove tough for them. It's possible they could lose water through respiration faster than their roots can take it up. One danger with passiflora is that many of them can't stand wet soil, so over-watering could cause root rot. You'll have to find some sort of balance there, between keeping them hydrated and not drowned.

You might well have better luck with incarnata and caerulea. Both will make it through your winters fine, and handle my (humid) Texas heat without flinching. My native incarnata in particular seems drought resistant, as it sends its roots much deeper than my other two, non-local incarnata plants.

You might try those 'mister' things- Surely you have seen them 'round Vegas. Extremely fine mist meant to cool the area more than water anything.. Place one a few feet above each plant & put them on a timer.. Tune it so they don't wilt so much during the day in that blast-furnace heat you guys have down there.

And good luck with that quad this winter- Hopefully you can keep it alive.

My suggestion is to take some cuttings as soon as it's large enough, and invest in a large pot. A quad isn't something I'd fancy investing all that time into growing only to lose it to the weather.

Thanks, all sounds like good advice. Will try to keep them alive.

Keeping fingers crossed.
Kmarie