Hard to believe we are past mid-July – already! NOW is the time to deal with the last bit of mid-season hydrangea care for July, ideally by August 1.
JULY HYDRANGEA CARE: PINCH PRUNE
Hydrangea care in July involves “pinch pruning” any of your hydrangeas that flower on old wood. What’s the science behind this? Old wood flowering hydrangeas (big leaf, mountain, climbing, and oak leaf) set their flower buds under two conditions: short day length (after June 21 in the northern hemisphere) and when night temperatures are consistently below 60 degrees. From that science we get our general rule of thumb: not to prune/cut these plants after about August 1 unless you’re prepared to risk cutting off next season’s flowers. But wait – someone said I’m not supposed to cut them at all! Yes and no.
Why then should you think about cutting them now? Simply stated, if you cut some of your newly grown stems now before August 1, you can accomplish two objectives: first, you stimulate that stem to branch into two more stems, optimally giving you a chance at two flowers at the tip next year instead of one. Mother Nature needs to give us a benign winter, of course. Second, you get a better view of this season’s flowers which are somewhat obscured by the newly produced stems.
HOW TO PINCH PRUNE
Here’s what you do. Step back and assess which of your plants have enough new growth on them that is hiding this year’s flowers and decide which stems you would like to cut. Make those cuts just above the place on the stem where the leaves meet it and where you see the growth of new stems emerging from it.
If you can’t decide which stems to cut, first go after the ones that may have leaf spots on them. You should be destroying those anyway as the spores of the fungus that causes those spots will continually plague your plant and reinfect it. I discuss insects and diseases in my book to give you a heads-up on what to look for and what to do.
When you cut these stems, you are forcing the growth hormones from the stem that you cut. Those hormones help the stem branch into those two new stems which will now grow out to form flowers at their tips. The plant does that on the short day length and consistently cool nights that come after August 1. In some parts of the country, however, those night temps won’t consistently be at 60 degrees or lower so you have a little wiggle room. But don’t wait too long. The weather is something over which you have little control.
If you are into making more plants, you can take the stems that you cut and propagate them. Voila! Free plants for a little work. Hydrangeas propagate very easily and my book has an entire chapter covering this.
PINCH PRUNING FOR THE FIRST TIME
If you haven’t pinch pruned before, treat this as an experiment. Don’t cut all the new growth stems — just a few and see what happens this year and next.
It’s up to you. If the winter weather cooperates, your pinch pruning will be a wild success and you’ll be awash in flowers next year. And you will have learned another new pruning skill.
HYDRANGEA CARE: TIDY UP YOUR OLD WOOD BLOOMERS
This pruning session can also be used to look for any dead, diseased, or damaged stems that won’t make it through the winter. Get rid of them now and stimulate your plant to make new stems before this season closes.
HYDRANGEA CARE: FERTILIZING, ROUND TWO
Your second chore is to fertilize your rebloomers one last time. The plants that need this are any reblooming big leaf hydrangeas, as well as your reblooming woodland babies. Your plants have been using enormous energy to push out that first flush of flowers and you want to give them all the help you can to keep the show going. Remember to use rose fertilizer or a granular fertilizer formulated for trees and shrubs.
If the product is organic, you should be all set. If you use a non-organic product, scan the ingredients label and avoid anything that lists imidacloprid. That is a chemical that is toxic to pollinators and should be avoided at all costs.
If you haven’t fertilized your non-reblooming plants this season and you’re unhappy with their performance, now is the time to do that. You’ll give the plant what it needs to thrive through the end of summer. Plus you’ll strengthen it to make it through the winter to perform at its best next year. Long term thinking is called for here.
If you can’t get to these chores by about August 1 (in cold climates), do your best to pinch-prune and fertilize as close to that date as possible. Global warming has pushed against that August 1 guideline. Keep in mind the science-based ground rule of needing nights consistently below 60 degrees. By paying attention to your local weather forecast and acting accordingly you may get some wiggle room to get these things done.
Warm climate gardeners have more leeway with the August guideline. Old wood bloomers need at least 6 weeks of nights below 60 degrees to form their flowers. So don’t wait too long as that weather window will close before you know it.
MY HYDRANGEA POSTS ON OTHER SITES
If you want to learn about hydrangea myth busting, CLICK HERE to read my latest post for Coast of Maine. I write a monthly post for them on a variety of gardening topics which may be of interest to you.
And lastly, if you’re interested in reading about why hydrangeas don’t bloom, CLICK HERE to read a post I just did for the National Garden Bureau about that. A lot of gardeners seem to be enjoying it.
Here’s to blooming hydrangeas, not a myth but a reality!
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