Has anyone here tried this and is it effective...have been told it will protect for a couple degrees (celcius) of frost.
Antitranspirant foliar spray
I believe one grower in Southern California did -- Jack of Kimi's Plumerias. I think it got down to 26 at his place, and he sustained some damage. Whether or not the damage was lessened is still undetermined, I think. If I'm not mistaken, these products are expensive, and they are usually used by large commercial growers with cash crops. This is his site: http://www.socalplumeriacare.com/Avoiding-Frost-Damage.htm