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To prune, or not to prune: That's the question for hydrangeas

To prune, or not to prune: That's the question for hydrangeas


I find it reassuring that my garden is awakening after its winter slumber, yawning in daffodil and tulip sprouts and plump lilac buds. After being cooped up indoors, first by winter and now by a contagious virus, gardeners are eager to get outdoors and set to work.

Many gardeners dread pruning in spring, especially when it comes to hydrangeas. Pruning at the wrong time of year will lop off a season’s worth of beautiful blooms. Most hydrangeas don’t need pruning. A quick haircut to remove spent blooms and broken or damaged stems is enough.

But sometimes a hard pruning is necessary to revive, shape up or rein in an older shrub. Two springs ago, I drastically pruned a trio of “Limelight” hydrangeas that had grown far out of bounds – so big that they threatened to swallow one side of the patio and so tall that its massive blooms loomed level with the garden house roof.

I cut them down by more than one-third, and honestly, I was apprehensive that I’d gone too far. But panicles can take a hard pruning and “Limelights” are especially vigorous and responded with strong stems and loads of cone-shaped blooms.

Figuring out what kind of hydrangeas you have will save you from making a pruning mistake. Panicle hydrangeas like “Limelight,” “Little Quick Fire,” “Bobo,” “Pinky Winky” and ““Vanilla Strawberry” produce cone-shaped, large flowers in shades of white, green and pink. Flowers mature to a beautiful dusty pink. You’ll never see blue flowers on a panicle hydrangea, and you can’t turn them blue with application of a soil acidifier.

Panicle hydrangeas bloom in the fall on new wood that grows during the current season. That’s why you can prune them in late winter and early spring. Always prune just above leaf joints.

Smooth hydrangeas (H. arborescens) bloom on new wood, as well. Varieties like “Incrediball,” “Invincibelle Spirit,” “Invincibelle Ruby” and “Annabelle” have large, round flowers in shades of white and pink.

These hydrangeas bloom on new wood earlier in the season than panicles, but like panicles won’t ever produce blue blooms. Prune these in late winter and early spring. Experts recommend cutting down no lower than 18 to 24 inches to maintain strong stems. If you do make a mistake, chances are the shrub will recover just fine.

All other hydrangeas, including oakleafs and so-called mopheads that can turn blue or pink, bloom on old wood. Prune after blooming and into fall. Pruning may not be necessary at all except to remove damaged or dead stems. Old wood varieties will grow in Zone 5, but may not be as cold hardy. If your old wood hydrangea loses its buds to freezing before it hardens off, you may not see blooms because the buds already formed were killed, according to the National Garden Bureau.

2020 David Austin Roses


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