I don't have the problem you have with pH,
@grhancock. I would think that with highly alkaline water, you would need to acidify it to get it into the neutral to slightly acidic range. I do not know your location and thus your climate (you can add that information on your profile so that it will be seen when you post), but like you, I root plumeria year 'round. Dormancy certainly will make rooting October through January tricky. Most people root their cuttings in the spring and summer, when active growth is taking place.
If you are in a very dry climate (low humidity), I think that you will benefit by misting your plants often. These are tropical trees and do best with high humidity.
