I transplanted a small trumpet vine from a stand of lush established plants over 5 years ago. It sends out long vines each spring and summer but has never once had a bloom on it.
Why Won’t My Trumpet Vine Bloom?
Certified GKH Gardening Expert
I would guess that the nitrogen to phosphorus ratio is off. The soil may have an abundance of nitrogen, which would result in nice, healthy green growth but little to no blooms. Without the right amount of phosphorus, it will not bloom well. Bone meal is a great way to add phosphorus. You may also be able to speed up flowering by pruning back the leaders to encourage more side shoots, where the flowers appear.