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Hydrangea confusion

Posted: November 14, 2024 at 10:11 am   /   by   /   comments (0)

Since I’ve started hosting a small radio call-in show for gardeners looking for help with their outdoor spaces, the phone lines have been jammed from the moment the show starts until the final credits. The radio show has taught me a few things, including that no matter how much is on the Internet, people still want to hear it from an expert.

This is in part because there are so many conflicting posts and blogs all on the same subject, which leads me into today’s article. I have been flooded with callers asking about hydrangeas and when to prune them. Online, there are so many different answers that I can see why there is confusion. So here is the deal with your hydrangeas and what to do at this time of the year.

There are three types of hydrangeas in Canada and they all need a little different attention. This is where homeowners get mixed messages, so let’s set the record straight.

Hydrangea macrophylla is also called the “Big leaf” hydrangea and anyone who has purchased one of the Endless summer cultivars has one of these hydrangeas. Most of the pink, mauve and blue varieties are macrophylla, but there are some white ones as well. Often they have big mop-head flowers, although there is more of the lacy-macrophylla in the garden centres now. Macrophylla blooms on old wood which means the the branches they grow all summer long are the ones that bloom the following year. If you prune these in the fall, you often prune off the flowers before they bloom. This hydrangea is pruned in the spring, after it blooms and you only trim off the spent flowers down to the pair of leaves.

Hydrangea arborescens is called the Smooth hydrangea and it includes the Annabelle cultivars. These hydrangeas have creamy flower heads that appear in the fall on top of that season’s growth. In Canada, these hydrangeas are either pruned to the ground or down to six inches in mid to late November because the stems die off in our cold winters. Annabelle hydrangeas have been reported to grow in zones 2 and 3 because they die back to the soil every fall.

The final group of hydrangeas is the Paniculata family. Also known as the grandifloras or the peegees, these hydrangeas need more sunlight than the other two shade-loving varieties. This type of hydrangea can handle pruning at any time of the year with the exception of summer when they are in bloom. What is nice about the paniculata hydrangea is their ability to be shaped into a tree-form making them more versatile than the other varieties. Look for favourites like Limelight which can get up to 10 feet tall in our climate.

Hopefully this has cleared up the hydrangea-confusion and if you want to get some personalized help, my radio show is now online through the station’s website cjbq.com.

carson@carsonarthur.com

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