here is a photo of the other vine that gets a bit more shade from an unruly olive tree.

and here is a close up of the leaves --- they seem to sprout and then after about a week shrivel up (but the leaf is still pliable, it's not crunchy) and then fall off.
Is this from over-watering? My husband does give them a lot of water because he is babying some new trees nearby.

Should I be feeding them, or ignoring them? We have a neighbor who appears to ignore their vine and it blooms and grows profusely only a few blocks away. But it's a well-established vine; probably a good 15 yrs old.

Hi,
Overwatering is definitely an issue with passionflower vines. They prefer well drained soil with sunshine. 'Lavender Lady' is also prone to a virus that causes discoloration to the leaves, but is usually not a cause of serious damage. Spider-mites cause a more "crunchy" looking leaf with discoloration and damage. Probably overwatering is the problem. It roots easily from cuttings, so if you need to reestablish your vines elsewhere, you can start some new plants. They are big butterfly and bee attractants, it's a vigorous and free flowering passionflower and new plants will pop up nearby.

Thank you, morningloree. That's what I was beginning to think, too. It's very hard to get out of the "everything green needs lots of water" mentality. I'll make sure the rest of the family knows to leave them alone!

For this winter, is there anything specific I can do since we won't really be watering?

Do the leaves that are on it look correct? They seem awfully dark to me when they emerge -- almost a green/black. I've started to notice tendrils just in the past week again, now that I've let up on the water.

I really appreciate the time and help, thank you!!

This passionflower naturally has dark green leaves with some reddish pink ribbing on some leaves and stems. For winter, mulching around the base, occasional water. Does not need a lot of fertilization, grows well in sandy, loamy soil. Will not fruit readily, maybe the occasional fruit, most fruits are empty. For temperatures below 35-40, maybe some leaf loss, but returns in spring. In Zone 9b faithfully returns with only mulch at base. Roots easily from cuttings, if you are concerned about overwintering, you can root a few cuttings for insurance.

Okay! I'll put some mulch on the base. I've never done a rooting, I'll look into that.
The soil is most certainly not sandy or loamy -- it is thick, clayish, black soil that has an awful lot of organic material in it, (we've been here a year and there was a lot of rotting stuff in the planter beds -- including worms!).
I'll hold my breath this winter during the rainy season and see what happens.
I appreciate your helpfulness, thank you!