Answer: Trumpet vines flower on new growth so pruning them back each spring will encourage lots of new flowering growth. They need sunshine and warmth in order to perform well - sometimes weather doesn't cooperate. And, they can sometimes take 3-4 years to establish before they will flower, which may be what's happening with your new trumpet vines. I would simply keep them well watered this summer, prune them back next spring and lightly feed in the spring with a 5-10-10 to promote flowering. Best wishes with your trumpet vines.
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