Hydrangea pruning isn’t rocket science, so don’t stress

If you’re like the millions of homeowners who grow hydrangeas, I bet you’ve spent at least a little time recently looking at one in your yard and wondering how you’re supposed to prune it.

People are so unsure about how to prune the popular shrubs — probably because they’ve falsely convinced that great tragedy awaits if they do it incorrectly — that questions on the topic remain the most frequently asked garden topic.

But it doesn’t have to be complicated or scary. In fact, the most difficult part of pruning hydrangeas is figuring out what kind you have. Once you have that part figured out, the rest is easy.

There are only two kinds of hydrangeas that should be pruned in spring as a matter of course: smooth hydrangeas and panicle hydrangeas. These types bloom on growth produced in the current year rather than on buds set the previous year.

Smooth hydrangeas (Hydrangea arborescens) are native to our region and are known for the most commonly planted variety, Annabelle. They typically produce large ball-shaped flowers that are white, although some varieties are pink and still others have flatter, lacecap flowers. They are never a shade of blue.

There are three approaches to pruning established smooth hydrangeas, and all work. The first is to prune them quite hard, taking down all stems to 6 to 8 inches long. Another option is to cut the stems back to about one-third of the plant’s size, typically 12 to 18 inches long. The final method, one used by Mt. Cuba native plant center,  is to cut a quarter to a third of the stems back all the way to the ground and simply remove old flowers from other stems.

Harder cut backs will result in fewer, larger flowers, and more moderate pruning will produce more flowers that are smaller. More drastic pruning can also lead to weaker stems that are prone to flopping and, if done for many consecutive years, can lead to general weakening of the plant.

The only other kind of hydrangeas that should be pruned in spring are panicle hydrangeas (H. paniculata), such as Limelight, Pee Gee and Vanilla Strawberry. These produce slightly pointed white flowers that often turn pink in autumn.

There is a good deal of latitude in how panicle hydrangeas can be pruned, but the result is the same as in smooth hydrangeas: more severe pruning produces fewer, bigger flowers, often on weaker stems, while more moderate pruning creates more, smaller flowers.

A good balance is to cut the plant back by about one-third and remove any dead or crossing branches that rub on each other as well as wispy growth. Prune to just above a bud, aiming for branching that will grow outward rather than into the center the shrub.

The best hydrangea pruning advice, other than to keep the pruners away from other varieties, is not to stress about it. If you mess it up, or even forget all together, your hydrangea will survive and you’ll have another chance to prune again the next year.