Answer: Failure to thrive can be caused by insufficient sunlight, poorly draining soils, lack of sufficient water or simply immaturity. If you are treating both your trees equally, and the growing sites and conditions are duplicated, your tree may just be taking extra time to become established. I would wait until after the normal bloom period and then prune them both back. Pruning will encourage new shoots, which may produce a second flush of bloom later in the summer. Pruning might also wake the slower growing one up and force new growth. let's hope so!
Best wishes with your trees!
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