What To Do With A Too Big Hydrangea

What To Do With A Too Big Hydrangea

“My hydrangea’s too big,” we hear our customers say. “How can I prune it?” Before we answer such a question, it’s important to know what kind of hydrangeas our clients have. Are they are blue lace caps or mopheads (Hydrangea macrophylla or H. serrata)? Or do they grow the pink or white smooth hydrangeas (Hydrangea arborescens) such as the Annabelle or Invincibelle Spirit? Perhaps our customers are growing the white panicle hydrangeas (H. paniculata) or the native oakleaf (Hydrangea quercifolia). All of these plants respond differently to pruning, so knowing which variety is being grown is important.

Before we get to specifics, and the all-important photos, it’s important to say this: it’s usually folly to try and control a plant’s size with pruning. First of all, you’re fighting the plant’s genetics, which are telling it to be a particular height, width and shape. Secondly, pruning always stimulates growth. So in cutting a plant back significantly, you might think that you’re making it smaller but the plant will quickly try and replace the growth that it’s lost. So the bottom line is that if a hydrangea is too large for the location where it has been growing, the best thing would be to move it and plant a smaller variety in that spot.

Additionally, if you prune down a blue lacecap or mophead, they will not only replace their height in one summer, but you’ll have very few flowers the following summer, no matter when you prune the shrub back.

The hydrangea in this photo was pruned back in the spring. You can see how few flowers are on the shrub, even though it’s grown to be just as tall as it was the previous year.
This is a Nikko Blue Hydrangea that was cut back to about 3 feet tall “neaten it up and make it shorter” in a fall cleanup. By early July of the following summer, it has grown to be six feet tall and eight feet wide again, with very few flowers. It was a shame too, because this shrub is out in the open where there is no reason to try and make it smaller!
These lacecap hydrangeas are above the window sills, but that allows the flowers to be seen from inside the house as well as outside. If this homeowner wanted shorter shrubs here, they can plant “Tuff Stuff” and move these to a different location.

The smooth hydrangeas, such as Annabelle, Incrediball, or Invinceabelle Spirit will still flower if they are cut back, but repeatedly pruning them down results in weaker stems that may bend over so that the flowers end up on the ground. Again, if these plants are too large for their location, transplant them elsewhere and put in a Wee White or Mini-Mauvette because these varieties will stay shorter.

If a smooth hydrangea is getting too close to a path or driveway, the stems that are closest to those areas can be cut at ground level to reduce the mass on that side. But cutting them back to try and make them shorter doesn’t work well.

Panicle hydrangeas such as Lime Light, Pinky Winky, Fire Light and so on can grow quite large. They will still flower if they are hard-pruned, but this often results in fast re-growth and larger flowers that weight the stems down. There are alternatives to trying to make a plant shorter, however. With panicle hydrangeas it’s often better to turn larger plants into small trees.

Here is a Pinky Winky Hydrangea that has grown to be about eight feet tall. Instead of fighting that size, it has been pruned from the ground up to expose five upright trunks so that now it’s growing as a small tree.
Lime Light is a plant that can grow ten to sixteen feet tall over time. This plant is about eight feet tall and wide right now, and it’s in the front of a shade garden. Instead of trying to make it smaller, the gardener will start to turn this into a small tree that has shade plants placed underneath. To prune in that manner, you start by removing all side branches on the bottom quarter of the plant the first year. The next year you can remove a few more, while letting the top continue to grow taller.
If you need a shorter panicle hydrangea, try Bobo, which grows to 4 or 5 feet tall and wide.

Panicle type hydrangeas that stay shorter include Bobo, Little Quick Fire, and Fire Light Tidbit. Little Lime is a medium-sized shrub (around 5 to 6 feet tall and wide).

Fall is a great time to move any Hydrangeas that are growing in the wrong spot. Dig them in early September and place the plants where they can be the size that their genetics are telling them to grow. Once moved, the only pruning you’ll have to do is to remove dead canes on the mopheads and lacecaps, and cut off dead wood and crossed/rubbing branches on the other varieties. When a plant is growing in the right place, you can prune to improve appearance and give up on trying to control the shrub’s size.

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