Answer: Trumpet vine blooms on the new growth of the season, so pruning it during summer will prevent it from blooming. If you need to control its size, trim it back very short in late winter or early spring. As it grows you can pinch the growing tips to encourage it to grow denser rather than taller, but ultimately it is a very large vine. Also, do not overfertilize it. An excess of nitrogen fertilizer will encouragevegetative growth at the expense of blooms. Finally, it will grow and bloom best in full sun; if it is in a shady location it would not bloom that much regardless. I hope this helps you troubleshoot.
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