nikko blue hydrangeas out of control...can i prune now?

kglvOctober 1, 2011

Hello all. We purchased a home last year with 5 yr old landscaping done by the previous owner. There is a row of 5 Nikko Blues up against the back side of the house. We LOVE them, the bright blue color, etc. But they are HUGE. They stick up past the window sills, and are so top heavy they fall over, taking up like 4' of patio (which we could definitely use back! :) Anyway, it's October 1st today. Am I going to regret it if we cut them back now? They have lost maybe half their leaves already and are looking pretty terrible. I'd like to cut them back to 1/2 to 2/3 their height, to avoid how overgrown they looked this year. I don't want to sacrifice all of next year's blooms, but I don't think I can make it through next summer without pruning them back. Thanks for any and all help!

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Unfortunately, you will have to sacrifice the blooms if you want to prune now. Hydrangeas like Nikko Blue bloom on old wood. Their flower buds develop starting in July-August so pruning now will remove the (now) invisible flower buds that will produce blooms in Spring 2012.

Some alternatives, none of which may be perfect....

If cutting them by a large amount (more than a third), you may want to do that in winter when the shrubs are really really dormant.

This option is called rejuvenation and you prune in thirds for 3 years only when the plant is dormant: cut the oldest 1/3 stems this year (prune them aaaalllll the way to the bottom); next year, prune the next 1/3; and on year 3, prune the last third. You could prune them this way -for example- every November for three years in a row (or do it every December, January, etc for three years in a row).

A variation of rejuvenation: leave the plants alone/unpruned now, let the shrubs bloom in Spring as usual, and then prune them in thirds as described on the next three Springs in a row. However, prune in thirds to the ground a few weeks after the bloomage show has started so you get to see & enjoy some of the show.

    Bookmark   October 1, 2011 at 12:51PM
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Are the flower buds at the very tips of the "old" wood (green, 2011 wood)? If I cut all the stems back by 1-2' but be sure to leave visible buds on the 2011 wood, will the plants still bloom in 2012? Thanks.

    Bookmark   October 3, 2011 at 1:10PM
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Yes, but some have flower buds further down. The remontant hydrangeas -if your prune their flower buds- will still generate blooms in 2012. The non-remontants ones will bloom again in Spring 2013. See this image of visible open buds for the sake of reference:

Here is a link that might be useful: Hydrangea flower buds

    Bookmark   October 3, 2011 at 7:34PM
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