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When Should I Cut Back My Hydrangeas?

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hydrageas growing in my yard A friend recently asked me when he should prune or cut back his hydrangeas that are growing in his landscape. Although I know a good deal about pruning, this answer required an explanation.

There are four basic types of Hydrangeas:

  1. Mophead
  2. Oakleaf
  3. PeeGee
  4. Annabelle
The first two types (Mophead, Oakleaf) produce buds on old wood, or stems that have been on the plant for more than a year. The best time to prune these varieties is after they are done blooming in the summer, but no later than the end of July since they set their buds for next year in August and September. You can also prune out dead and crossing branches in the fall. The older the wood that you remove, the fewer blooms produced the following summer. The other two varieties, PeeGee and Annabelle, produce buds on the new growth each year. These hardy plants can be pruned to the ground every fall and they will regrow each spring with new buds on the new wood. This drastic pruning can take its toll on these plants and they may become weaker with age. How do you tell which variety you have in your landscape? I suggest you click on this link. This website is a great resource, providing identification clues and descriptions to determine what type of hydrangeas you have in your landscape. Most spring flowering shrubs have already set the flower buds for next year. If a deciduous shrub that flowers in the spring is pruned in an effort to shape it, there is a good possibility that all the buds will be removed.

Pruning should accomplish one of two tasks – shaping or thinning. 

Personally, I am not a big fan of tightly pruned hedges or other bushes, either deciduous or evergreen. I will admit that I do shape a hedge of cotoneasters. I used to prune them with a hand pruner, but it would take way too long to trim 20-foot rows of bushes that were about 4 feet high and 3 feet wide. Many homeowners like the clean look of shaped shrubs, but I prefer a little wilder look. Thinning your shrubs and trees is the process of removing certain branches due to concerns such as crossing branches, broken branches, and branches growing in to the canopy or low hanging branches. This type of pruning can be done at any time of the year. Winter is a great time to prune to improve air flow, increase sunlight to the ground underneath the plant and remove limbs that may be growing in the wrong direction or are causing an obstruction. At least in winter you don’t need to worry about leaves. Getting back to the original question as to when to prune back a hydrangea, the answer depends on the type of hydrangea that is in your landscape. I would suggest determining the type of hydrangea he has so that the pruning is completed at the right time.