Hmm, I think I've seen your question before?

Anyway, star jasmine vines (we're talking trachelospermum jasminoides here, aka star jasmine, not jasminum nitidum?) often drop lower leaves as they get older, but I'm betting that the spray from the sprinklers isn't doing them much good, especially in a high humidity environment. It's hard to tell if you're watering correctly without more info on the size of the vines, the soil, etc., but generally they're better off with deeper waterings every couple of days than a daily light soak with a sprinkler. Any chance you can move the sprinklers or switch to drip irrigation?

It's not easy moving soil ph that much, but if your soil is very compact, that may be a problem right there -- particularly if they just got dropped in a small hole right from their nursery containers. If they're really looking sad, you may have to dig 'em up and replant in a hole at least twice as wide and deep as the original container or the size of the rootball, and dig a few cubic feet of peat moss or sharp sand or perlite into the soil to lighten it up. Hope this helps!

Jim

Even a lawn doesn't need daily five minute sprinklings but better twice a week for a lot longer. You want deep watering, not light sprinklings.