Q.cutting back oakleaf hydrangea
One oakleaf hydrangea seems to be dead, perhaps from winterkill – no new growth, though stems seem still flexible and green. Another planted nearby has new growth, but older stems in the same condition as the apparently dead shrub. Should the older non-growing stems be cut back? Any chance that new growth will begin from the roots of the “dead” one?
The soil is clay beneath several inches of amended soil and mulch, in a half-shaded location in zone 7.
Certified GKH Gardening Expert
They are fully hardy in your area. Winter will not affect them in that way. Can you include photos? Fungal issues are common over winter, but I won't be able to confirm anything without some photos.
In the meantimes, this article will give you more information on the care of these: https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/care-for-oakleaf-hydrangea.htm
My oakleaf hydrangeas suffered some winter dieback also. Roses suffered the same fate. For me, in Michigan, I think this was a fluke of late autumn/early winter weather. Fall was unusually warm and plants didn't get the signal to shut down for winter, a process that takes up to 6 weeks. Then mid-December had two nights with lows in the teens. This combination is what I believe led to dieback. Don't rule out new growth from the plant just yet. For winter protection, it is important to water shrubs and trees thoroughly in late fall if the weather has been dry. Plants that go into winter dry will suffer more winter injury than a well-hydrated one. Good luck with your oakleaf hydrangea.
