Pruning leaf growth?

slyefox1(6)July 23, 2012

We have about 20 Endless Summer hydrangeas near our pool that have had a huge burst of leaf growth in the past 2-3 weeks. The plants have all shot up several long stems with the biggest leaves I have ever seen on them (think 10" dinner plate) that are now 1/3 to 1/2 taller than the rest of the bush (main bushes are about 42"). This new growth is burying the blooms that previously set and flowered so you can barely see them. There is absolutely no sign of flower buds on this new growth, just many more giant leaves. We are not fertilizing them at all, but the weather here has been very warm and sunny for the past month. Can anyone advise whether we can prune off the heights of these new shoots (like 12-15") to keep them from over growing and stop them from smothering the blooms we do have? If we lightly prune this runner growth now, will the plants send out the correct shoots to make fall blossoms? Or by pruning those long runners are we cutting off the second round of blooms that ES hydrangeas give us in September?

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springwood_gardens(6B Pittsburgh)

Growth bursts are normal, especially after periods of increased or heavy rains (had flooding rains here!). I don't think pruning off a foot would hurt anything for the sake of tidying up appearances. After all, that current height is almost the maximum height ES supposedly reaches.

I think the main thing you need to consider is next year's size and bloomage, and the overall structure of the plant in future years. These large stems/leaves aren't unusual; mine do the exact same thing as what you describe. The huge leaves nourish the plant and give it energy to continue growing. Unfortunately ES can't seem to both grow taller and bloom profusely at the same time without exceptional conditions.

BUT, these new tall shoots will harden and provide structural stability with a lot of extra blooms up top next year, *if* these stems live through the winter. (Remember, it's those current year's stems whose blooms flop to the ground). However, even if the top 2' dies back, you still have some nice 2' tall hard stems that will help prevent future bloom flop.

Now, these new stems may or may not produce a set of blooms before fall; they would just have to "decide" to stop growing taller first. You could try another dose of fertilizer (on a test plant or two since you have 20), but this would FINAL time of year you'd want to do this, as the plants need time to wind down before winter hits.

Lastly, I think back through all the reviews about ES over the years, and the prime scenario is a harmonious balance between blooms on new and old growth, and it seems like your plants are definitely getting there.

    Bookmark   July 23, 2012 at 12:07PM
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