Pruning Hydrangea

Yesterday my husband and I drove by a new store that recently opened.  He commented on the plantings from last year; “looks like they have a bunch of dead shrubs.”  I take a quick look and identify them as hydrangea with last year’s dried blooms not yet trimmed away.  I inform him that we have the same in our yard.  

Left:  My Hydrangea bed on April 26.

I like the look of the dried flowers that have survived above the snow line and given me pleasure all winter.  But I guess it is time to give them a good pruning.   It is a question that is frequently asked and most gardeners have an answer for what they do with theirs and are happy to advise.  Many of us, including me, do as we were told many years ago.   
I was surprised to learn last year from a nursery employee that hydrangeas are quite happy without much pruning.  Each type of hydrangea has its own pruning instructions.  For us in the north, we do not have to worry about Hydrangea macrophylla (mophead) or Hydrangea quercifolia (oak-leaf) since they are hardy only to zone 5. Here is what you need to know about the rest.

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In my zone 3 yard the Hydrangea arborescens 'Annabelle' starts with green buds in early July that quickly bloom to a cream color and by September turn another shade of green before drying to a brown that lasts through the  winter.   

• ​Hydrangea arborescens ‘Annabelle’ is the most popular of these hydrangea; other cultivars include ‘Incrediball’ and ‘Invincibelle Spirit’.  These all flower on new wood and are hardy to zone 3.  According to the Missouri Botanical Garden it is native to the eastern United States.  This plant can be pruned anywhere from last year’s blooms to the ground and will grow again to produce flowers this year.  You probably want to prune out any broken stems and last year’s blooms and then it is your choice how close to the ground you want to go.  Last year I pruned some within inches of the ground and others only under last year’s flowers.  The result was the same no matter how much I pruned.  I have noticed that when I do not prune the next year's blooms are smaller.

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Left:  Hydrangea paniculata 'Tardiva' blooms in August, turns to a pink in the fall. 
Right:  Hydrangea paniculata 'Limelight' at the Minnesota Landscape Arboretum in June with last year's dried blooms. 

• Hydrangea paniculate are hardy to zone 3 and native to China and Japan.  Many new cultivars have come out from this type with names such as ‘Pee Gee’, ‘Limelight’, and ‘Pinky Winky’.  These require no pruning, although you may want to trim out last year’s blooms and any old stems.  I noticed at the Minnesota Landscape Arborteum last June that they did not even prune off the old blooms.  These hydrangeas can also be pruned close to the ground if you want to renew your plant.  

​So try not to stress about where to prune hydrangea.  Those that are hardy in our area are forgiving in their needs.  They can be pruned in the fall through spring depending on your choice and what you appreciate in this plant.   What other plant provides interest in three seasons from July to the next April?