Advice on pruning hydrangeas

Beckie Fox

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hydrangeas

Even experienced gardeners may hesitate before picking up secateurs to prune their hydrangeas. Some types are pruned now, some later, some rarely — which is which?

The timing of pruning depends on the species. Those that bloom on new wood, such as smooth or mountain hydrangea (H. arborescens) and panicle hydrangea (H. paniculata), are pruned early. Oakleaf; climbing; and bigleaf, hortensia, lacecap, mophead (different common names used for H. macrophylla) bloom on old wood and are generally pruned minimally — if at all — after they bloom. For more details on pruning hydrangea, see “Pruning on Your Mind” and “Bountiful Midsummer Flowers: Hardy Hydrangeas“.

Invincibelle Spirit hydrangea
Invincibelle Spirit, a mountain hydrangea, blooms on new wood and is pruned in early spring.

During a warm sunny day this week, I cut back our half dozen ‘Annabelle’ hydrangeas to about 18 inches (45 cm) above ground; some gardeners go as low as ground level. Each year, I try to remember to prune them in late winter (or very early spring, depending on your perspective), when the leaf buds are just beginning to swell but before they open. However, sometimes I get busy with other tasks and they go unpruned, or they’re pruned a bit later. No great harm is done, although I end up with fewer, smaller flower heads. 

Hummingbirds on the move

If you’d like to keep abreast of this year’s hummingbird migration, here’s a neat map you can bookmark to follow their movement across North America.

Hummingbirds tend to return to the same area — even the same feeder or garden — as the year before, so you’d best be prepared for them. Here’s a list of their favourite flowers and other tips. You’ll want to have a healthy meal ready to welcome them home.

Sowing peas

St. Patrick’s Day is near, which may mean green beer and soda bread for some, but for many gardeners, March 17 is considered the traditional day to sow peas. This makes sense because the soil is usually thawed and days are cool, but superstition aside, there are other factors to consider before sowing

Healthy gardeners

A recent BBC article reports on research that attributes gardening as a factor in the longevity of the world’s centenarians. Other research shows gardening may also lower the risk of dementia, reduce stress and help lower blood pressure. But we all knew that, didn’t we?

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2 thoughts on “Advice on pruning hydrangeas”

  1. Hi there I have Nikko Blue 4 of them about 15 years old in my front garden. The last few years they have been sparse with flowers they are in good draining soil and get lots of water as needed. I have not cut out or pruned anything as I’m not sure what to prune which branches are second year growth. I’m in Oakville and local Hort says to cot right back to ground any advice? Thank you.

    Reply
    • I found this on the Toronto Master Gardener website: “The best time to prune Nikko Blue hydrangea is after the flowers are ending in Sept or Oct. Nikko Blues bloom on old wood unlike many other hydrangeas. Cut off the blooms just below the bloom. Look down the stem and find a new set of buds starting up. Make a straight cut half an inch above the bud. Stand back and check the shape of the hydrangea periodically and adjust where you are cutting to suit the site and shape of plant you want.

      If your Nikko Blue is in a cold or windy location, you might want to only cut off the flowers in the fall and then prune just above the buds in the spring after you see how much winter kill there is. If rain is forecasted for the next three days, it’s advised that you not prune until after then as water-borne bacteria could get in to the plant.”

      Reply

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