I have had my grape wisteria for four years and it still has not bloomed. What do you suggest?
Certified GKH Gardening Expert
These vines can be slow to bloom. However, you should check out a few possibilities. Is it getting enough light? Wisteria need a minimum of six hours of sunlight a day to bloom. What about fertilizer? Too much nitrogen can slow flower production, as it spawns heavier top growth. Try adding phosphorus instead. Finally, has it been pruned? Wisteria should not be pruned past mid summer, as they set flower buds in fall and bloom in spring. If none of these applies, and given the vine is not overly large, you could try to root prune the plant in July or early August. Dig straight down (with a straight-edged shovel) in a staggered or spread out circular pattern about a foot away from the plant. This should cut some roots (not all, because it is not a complete ring) and slow down the top growth. Often this encourages the plant to begin setting flower buds.