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Truth in Advertising Hydrangea macrophylla zone hardiness

My husband and I started a nursery and I'm working on the plant descriptions (have been for months!).


Currently, I'm struggling with realistic zone hardiness of Hydrangea macrophylla. My inclination is to give it Zone 7a maximum cold hardiness for reliable success. Some being more cold hardy in Zone 6, such as Dooley, Endless Summer, Lady in Red, Twist-n-Shout, and maybe a few others. My thinking is that zone 6 hardiness for other bigleaf hydrangea cultivars is only for advanced, dedicated, and determined gardeners.


However, on this fascinating forum, I'm seeing regular mention of not only zone 6, but of zones 5 and 4! I am having a hard time coming to terms with success in those zones, yet it seems that gardeners are more than willing to take the risk and eagerly struggling to get blooms in those cold zones. I love seeing such passion!


I understand that Endless Summer was discovered growing outside in Zone 4b, but is that realistic for my customers?


Please, dear Hydrangea lovers, give me your advice. Is it best as a retail nursery who wants to present accurate information (even at the risk of missing some sales) to play it safe and list zone 7 (sometimes 6) as the uppermost cold hardiness range for H. macrophylla? I want happy customers and I want new gardeners to be successful.


Or . . . should I write many many disclaimers (and even link back to this forum) about gardeners attempting growth and bloom in zones 6, 5, and 4?


Please send me your advice!


With much appreciation from Zone 8a,

Hillary

Comments (22)

  • 7 years ago

    I love that you want to be honest in your recommendation of macrophyllas..I've been messing with macs for over 20 years with LOTS of disappointment..I think Endless Summer promotion IS misleading..I love the reaction at a garden center when I tell strangers (if they seem approachable and I have time) "these hydrangeas aren't bud hardy in our zone"..then I say "how many do YOU see blooming when you're driving around?"..you can see the wheels turning..

    Cutting Edge Plants thanked nicholsworth Z6 Indianapolis
  • PRO
    7 years ago

    Thank you both for your replies! Sadly here in zone 8a near Atlanta, Georgia, flowering of macs is not a sure thing. That's why I'm jittery about listing colder zones and why I've sought input. Thank you both for your perspectives!

  • 7 years ago
    last modified: 7 years ago

    Oh, I would never say that Zone 8 is a sure thing. It wasn't when I lived in Atlanta and it does not here either. Sigh. :o( I have not kept records of when I get no blooms here but, I would estimate that in a 10 year long period, I may not get blooms in 2-3 of those. All it takes is a single cold weather event that drops the temps low enough.... and the flower buds are history so try not to use those zones as a way to guarantee bloomage or you will go crazy. The shrubs in protected locations fare better blooming-wise.

    The only good thing is that my growing season is long and reblooming varieties have not had issues where the new wood is unable to mature & bloom before winter strikes early. Meaning I get blooms from the new wood reliably. Of course, there was this drip irrigation incident that will not be mentioned... hee hee hee! ;0)

    Oakleaf hydrangeas also perform much better, blooming wise, than macs for me, although RS does the worst. If you want a suggestion, have the customers sprinkle several varieties... like macrophyllas with oakleaf & Annabelle-like hydrangeas. That way, if one gets zapped, other varieties can try to pick up the slack. PS - Annabelle flower buds develop from new wood but they were not immune to blooming issues to me.... the squirrels and deer eat them so it is possible to get a weird looking Annabelle with just a sprinkle of blooms or hardly any blooms in some years. Oh Lord. Ha!!!! ;o)

    Cutting Edge Plants thanked luis_pr
  • 7 years ago

    I have lived in a zone 8 climate my entire gardening life (40+ years) and never once have I experienced any loss of hydrangea flowers due to cold. Deer, yes - cold, no! We just do not get that cold in winter and I can't recall any late season heavy frosts.......heck, we only got a light frost a couple of times this winter and nothing below freezing since the end of January!! My macs seldom even go fully dormant, let alone lose any latent buds.

    But this is coming from a purely west coast perspective. The climate in the eastern half of the US is beyond my understanding ;-))

  • 7 years ago
    last modified: 7 years ago

    Oh, I love your PNW weather. The nearby ocean may help moderate your zone 8 weather. In my visits to Olympic National Park, Bellingham and Vancouver (very close to the sea all of them), I always noticed how nice the weather in WA was (well, it rained sometimes and that is fine with me)... regardless of when I visited but December visits tended to feel the coldest.

    Say, gardendal48... I do not remember. Are you now living in WA State? You mentioned once that you had recently moved from some place in Oregon. Are you still in Oregon?

  • 7 years ago

    Have never lived in Oregon. Traveled there often and also in SoCal (my sister lived there for years) so very familiar with the area but I have always lived in WA state. I did move about 10 years ago but just from the east side of Puget Sound (Seattle area) to the west side. I currently live on an island so yes, the marine influence is strong but it is pretty much anywhere immediately adjacent to the Sound.

    And I think the PNW weather is pretty spectacular, as long as you don't mind gray, wet winters :-) Hardly ever get any snow, very few severe cold snaps (barely even had a frost last winter!) and no hurricanes or tornadoes or rampaging storms. And no summer humidity. Combine what I consider excellent weather with one of the most scenic locations on earth and I would never consider moving anywhere else!!

    And boy, can we ever grow hydrangeas here!!

  • PRO
    7 years ago
    last modified: 7 years ago

    Thank y'all for the continued insight! Luis_pr, I love this quote, "so try not to use those zones as a way to guarantee bloomage or you will go crazy." So true and I think I was getting caught up in that even thought I know better! :)

  • 7 years ago

    I never see anyone in Pittsburgh use winter protection. I planted numerous Mac's last year. Both my Tuff Stuff lost only a few latent buds, my LAD had almost no die back. However, my Endless Summer and Pistachio had a lot of die back - only a handful of latent buds survived. It really seems to vary - my dad's Mac's, except his Tuff Stuff, all died to the ground (he lives 10-minutes away), but most of my neighbors seemed to have very little die back.

    Cutting Edge Plants thanked Jon
  • PRO
    7 years ago
    last modified: 7 years ago

    Thank you Jon for sending info from Pittsburgh. Am really getting good perspectives from different climates across the country. Tell me, by LAD is that Lady in Red?

  • 7 years ago

    Sorry - LA Dreamin'. I've heard its closely related to Endless Summer, as in an early reblooming cultivar, but it is quite different: richer rather than pastel flowers, shorter internodes, darkers and tougher leaves. Folks who said it is similar to ES said it might not do as well in Pittsburgh as some newer, slightly hardier cultivars. Other people say Macs are Macs and variety doesn't make much difference.

    I guess my point being that, in my eyes as a consumer, these plants do well and meet my expectations in Pittsburgh. Consequently, I would think they should meet a reasonable person's expectations in zone 8: maybe some risk for winter die-back, low risk that the plant will actually die.

    Cutting Edge Plants thanked Jon
  • 7 years ago

    I don't think there is a universal rule on how these things behave to some degree.....location, soil, cold temps but sheltered from wind, etc, etc ? really terrible analogy, but take a bottle of soap. My water and the experience with the soap may be a complete different experience with someone else using the same bottle with their water source.


    Hillary. I applaud your effort. My nursery will only sell annuals that are not impervious to current local viruses floating around - that are known to kill off said annuals or the continuation of spreading them. Where the local big big stores continue to sell them in droves for every black spring friday/mothers day.

    Cutting Edge Plants thanked a1an
  • PRO
    7 years ago

    a1an, Having taken a soap making class a few weeks ago, the chemistry of soap is a terrific analogy!

    In our write-ups I want to be as clear and honest as possible about macs, without discouraging anyone. What I write and present on our website will be an evolving beast, I'm sure! It will be interesting to see how my descriptions, advice, caveats, and coaching develops over time, as I learn how our customers behave.

    Thank you for taking your time to write yesterday.

  • 7 years ago
    last modified: 7 years ago


    Hi Hillary, I wish you the best in your new adventure love that you are taking into consideration the people in our neck of the woods ...

    Macs are a real lot of work ( Winter Protectiom)... I have done the bent to ground with great success... over the last 5 yrs ( without WP) getting old ....very few blooms starting to replace my ES....here are a few picture with Winter Pro ...that 3/4 yrs were you see Hundreds of blooms I now get maybe 1/2 dozen on each plant... I had about 10 ES i’m down to about four ... Too many Hys that bloom every year ...Just Saying

    Cutting Edge Plants thanked hyed
  • 7 years ago

    For starters, let us recall what USDA hardiness zones mean: average lowest low. This mean's what, early January usually? Far as hydrangeas go, this strictly refers to the WINTER danger of buds being killed during dormancy.

    Now here's why hardiness zones mean nothing once SPRING hits:

    If you think about the basic math concept of sine waves, insert global warming. You end up with more volatile weather patterns, because the "push and shove" of cold/warm air masses becomes greater. Now apply these concepts to hydrangea macrophylla, which like to grow in mild or stable climates. Not a good mix! Most macs can be root-hardy down to zone 4 but the above-ground results will always vary greatly. Buds are breaking dormancy in February, which is a death sentence in most cases, since you're basically hoping for zero late freezes between Feb and May - normally mathematically impossible! I can expect a sum of 90% above-ground dieback in borderline zone 7, simply because the number of freezes post-dormancy is ridiculous - usually between 1-2 dozen. These plants can put up with a little late freeze abuse, but repeated beat-downs does a number. You're faced with cutting bundles of dead stalks in May every year.

    Cutting Edge Plants thanked October_Gardens
  • 7 years ago

    Earl May (local chain nursery in Iowa) has the ES bloomstruck listed at zone 4. Biggest waste of $50.00. I’ve spoken with numerous others in my state/surrounding states and none have had good luck with blooms any subsequent season

    Cutting Edge Plants thanked Sara Titus
  • 7 years ago

    Funny these ES bloomstruck. I'm North of International Falls MN (The icebox of the nation they call themselves)...Zone 3. 2 ES's, planted in spring '15 and they grew some. Summer of '16 great foliage but no flowers. Winter of '16-'17 mild for us up here (but still LOTS of -22F (-29C) in Dec/Jan and -13F (-24C in Feb/March)...yes that's mild for us lol. Summer of '17 we had our first crop of bloomstruck and they were plentiful and gorgeous. We were awed.

    Winter of '17/'18 was brutally cold hitting -40F/C a few times. Here it is May 30, everything in the yard is "up" as expected. Except the ES. Stalks are light brown/tan and just in the last couple days a little greenery is coming at the very bottom of the plant. I'll be surprised if we even get decent foliage never mind flowers. Meanwhile we have Annabelle's at 3 different locations in yard for 20+ years. Never fail to blossom and are quite spectalular (with literally NO winter protection).

    Probably last summer with flowers was a fluke, winters are just so cold here. Regardless, if we don't get at least a few flowers on each bush this summer they will be coming out.

    I don't know why people with mild winters when temps rarely get below freezing have problems with ES. Unless the breed itself is very finicky. Anyway, reading several threads on the ES's seems a lot of folks everywhere have issues with these. As a long time retailer (not nursery plants) the last thing we ever wanted was an un happy customer. If you haven't grown them yourself and had success with them, I don't know that I would even bother offering them for sale if I were you.

  • 7 years ago

    "I don't know why people with mild winters when temps rarely get below freezing have problems with ES."

    They don't :-) ES grows like a weed here and reliably blooms all summer long.....just like any other bigleaf hydrangea. In fact, they can grow to about twice the size typically listed.

    I think the majority of difficulties with this plant are in colder areas that would require winter protection for any other mac. It is the current season flowering that is sparse or nonexistent.

  • 7 years ago

    ES also struggles with heat more than fradition Macs. I have grown about 6-7 ESs on the gulf coast and in North Texas and they always have wilted bad. Have a nantucket blue this year and it hardly even shows heat stress.

  • 7 years ago

    I've read other past threads re: KCB7b / ES/ wilt. For the recent participants in this thread, can anyone confirm or deny


    In the same bed where I have my Let's Dance, LD has not wilted but the Bloomstruck has shown leaf wilt a couple times already

  • 7 years ago

    Hillary, first off, good luck with your new business. Your website is beautiful and you are offering a very interesting mix of plants! Love it. I too write plant descriptions for our website/ catalog/ tags and it is not easy. Plants are not widgets or plastic trinkets the remain static. They change with the season, with age, with weather, soils and climate. As for hardiness, most plants, particularly coastal Japanese plants die (or fail to flower) in spring due to our continental climate and the wild temperature swings we get from Feb-May. So unfortunately, winter hardiness ratings do not tell the whole story. This is difficult to convey on a small plant tag or even in a catalog description. But with an online store, you do have space to tell the whole story.

    As for Hydrangea macrophylla, most are root hardy here in zone 5 and most will not flower. Newer breeding (ES & LD) has changed that, and we now get flowers in zone 5.

    Cutting Edge Plants thanked Tim Wood
  • 7 years ago

    a1an I can also say that I planted a couple of small bloomstruck last year and they did about the same as ES for me, than we were gone over the labor day weekend and they got absolutely fried while we were gone. They weren't in the best location. New house I thought they would have more shade than they did, but even so both bloomstruck last year and ES in years past have not handled heat well for me. Grumpy Gardener at southern living reports similar experiences with ES. My experiences are worse than his, but the Rolling plains of North Texas are hotter, dryer, windier, and the sun is more intense than you find in Alabama.


    https://www.southernliving.com/garden/grumpy-gardener/the-truth-about-endless-summer

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