Hello Terri
Since you are in a zone that is definitely not kind to this tropical tree, the only way you will see blooms is if you supplement both heat and light to extend the growing season. Even if you had a longer season the quality of your sunlight isn't enough to make the plumeria happy. You could see blooms if you acquired a plant that already has an inflo, but repeat blooming would be highly unlikely.
Having said that, there are plenty of successful northern growers.
@GordonHawk who is in Brooklyn may have some suggestions!
