Winter’s Impact On Hydrangeas Part Two

Local Winter Temperature Chart 2017-2018

Table showing temps in winter 2017-2018

This is the second of two reports on winter’s impact on hydrangeas. A brief recap here. In my last post, I detailed how I went out in May to assess winter’s damage, fearing the worst. We had had a 2 week stretch of exceptionally cold winter weather which typically freezes the flowers buds that sleep in the stems of hydrangeas that bloom on old wood. You can get all the details on that report by going here.


Here’s what happened to my mountain hydrangeas, botanically known as hydrangea serrata. A little background here. Mountain hydrangeas are so called because they come from the mountains of Japan and Korea. The best part of that heritage is that they are better adapted to sustain cold climates and winter conditions. Which is just dandy for those of us who have to put up with Mother Nature’s challenges.

Unlike my bigleaf hydrangea macrophyllas, every single one of my mountain hydrangeas had flower buds on them, regardless of where they were sited. Some had a little tip dieback as shown in this photo, but none had total stem dieback.

Winter's impact on this hydrangea killed the main stem but not he side shootsPhoto of mountain hydrangea flowering below dead tip

Some hydrangeas can flower from side shoots when a tip dies back.


My first inspection tour was on May 3 (after one of the coldest Aprils on record) where my heart leapt when I saw signs of life on serrata stems. Then on June 3, those little “broccoli” heads were clearly there as seen in this photo below of Hydrangea serrata Tiny TuffStuff™:

Photo of hydrangea serrata Tiny TuffStuff™ showing "broccoli" 

Hydrangea serrata Tiny TuffStuff™ showing “broccoli”

I had a “mummy” on one tip of this hydrangea serrata TuffStuff™ (a mummy is a bud from last year that didn’t open and froze on the plant during winter). But now that the tip is dead, the growth hormones traveled down the stem. Ergo, this plant’s reblooming power is producing flowers all along the stem as shown in this next close up photo:

Photo of "mummy" on hydrangea serrata TuffStuff™

“Mummy” on Hydrangea Serrata TuffStuff™


But the best surprise of all is a relatively new acquisition, hydrangea serrata ‘Hallasan’, sometimes listed as ‘Spreading Beauty’. It is native to the Hallasan National Park in South Korea and is described as a dwarf ground cover. It could grow as much as thirty inches tall according to Corinne Mallet, a renowned French international hydrangea expert. But as a ground cover I would expect it to keep a much lower profile (more like 18 inches) as it trails along the ground putting out flowers along its stem. Look at the photo below to see how it looked on June 3 after its first winter in my icy zone 5 Connecticut garden:

Photo of hydrangea serrata 'Hallasan'

Hydrangea serrata ‘Hallasan’ displaying buds along stem


And it has just begun to flower as seen on July 3:

Photo of hydrangea serrata 'Hallasan’ flowering on July 3

Hydrangea serrata ‘Hallasan’ flowering July 3



This plant is pH sensitive so one can change the color of the flowers if desired. But I don’t need any more to do and since this plant is growing near the alkaline foundation of the house, it will most likely stay on the pink side which is just fine with me.

I am excited to use this small dependable hydrangea in other places, especially as a substitute for perennials. It is small enough to do a great job with no maintenance at all. But be warned that it is hard to find. You will have to use your search engine to seek it out but if we gardeners persist, the market may just respond and deliver for us.


My conclusions from this past winter’s experiences are two:

  •               First as discussed in part one of my report: reblooming hydrangeas are the better way to go if you have a choice and especially if you garden in zone 5 or colder or if you garden where you can have an unpredictable cold snap. Where the tips of my plants died back, if they have reblooming capability they produced flowers before the season ended. In some cases, those are the flowers I am seeing now. And if you don’t garden in a cold climate, magical rebloomers can give you continuous flowering. What’s not to like?
  •               Second, mountain hydrangeas (serratas) and especially the rebloomers are as close as you can get to a foolproof mophead/lacecap look-alike. That mountain heritage makes them tough as nails and now with a reblooming gene thrown into the mix, they are unstoppable. That is what is making Endless Summer® BloomStruck® such a winner: it is part serrata AND a rebloomer. This is what BloomStruck® looked like on July 2:
    Photo hydrangea macrophylla Endless Summer® BloomStruck® flowering July 2

    Hydrangea macrophylla Endless Summer® BloomStruck® flowering July 2 (CT)


    If you didn’t already know, Cape Cod has an annual Hydrangea Festival which runs this year from July 6-15. There are garden tours, lectures and presentations and an endless display of beautiful plants to enjoy. Go here for more information about it.

    I am honored this year to be a part of the festivities.For my small part, you can listen to me on the radio or speak with me in person.

    On Saturday morning, July 7, I will be a guest on IheartRadio with C.L.Fornari, The Garden Lady. C.L. hosts a weekly radio call in show. The program is called GardenLine and is broadcast every Saturday morning on WXTK – 95.1 FM, from 8:00 to 10:00 AM Eastern time. You can also hear GardenLine streamed on WXTK.

    As listed on my calendar, if you find yourself anywhere near Hyannis, on Sunday, July 8 at 1 p.m., come and meet me at Hyannis Country Garden Garden Center. I’ll be speaking about hydrangeas (what else??).

    Here is their contact information:

    380 West Main Street Hyannis, MA 02601
    1-508-775-8703 or
    In the meantime, enjoy your hydrangeas. Now is their time!

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