They should be root hardy but you may experience a lot of dieback - even back to the soil line - if you didn't provide some sort of protection. If that happens, yes, early blooms (and 'spring' is a VERY optimistic bloom time for hydrangeas anywhere other than in very warm southern zones - bigleaf hydrangeas are typically mid to late summer bloomers in northern gardens) will be lost. Depending on their siting and how well established and your summer weather, it may be possible these will produce flowers from growth produced during the season, but there is no guarantee. They need to produce enough new growth to accomplish that and a sufficiently long and warm growing season and that is often difficult to achieve if they have been cut back hard by cold.

The bottom line is that even remontant hydrangeas (those that bloom on both old and new growth) need winter protection of the stems and buds to ensure they are not damaged by winter cold or experience complete, above ground dieback.

You could also be on the lookout for and try the new Invincibelle Hydrangea. It is a pink (only) form of Annabelle that will be introduced in 2010 :o( It can be grown in colder zones than yours so this cold should not bother it. The problem -for now- is that it is not for sale, yet. Also, I am not sure how true vendor claims will turn out to be, it may be expensive & difficult to find at first. It only blooms pink but it is supposed to be good to Zone 3 and it reblooms!

Other alternatives are the regular Annabelle (Zone 4) and Paniculatas (Zone 4 but these have original blooms in white only, not blue or pink). From the paniculatas, you could investigate PeeGee, Limelight, Pinky Winky, Pink Diamond, Tardiva, etc. All these are Very Hardy in Zone 5.

PS - Winter here has not been abnormally cold but it has been moving the temperatures all over the map so I am afraid it may similarly affect my hydrangeas. Last time this happened, I had zero dieback but flower buds got killed and I had a total of just two blooms from all the hydrangeas. TWO! Grrrrrrr...... Oh well.... Cannot fight Mother Nature.... Some of my camellias are blooming nicely but some are also getting bud drop and, that happened the year I got just two hydrangea blooms. I need to add some hydrangea rebloomers like ES around here but I am out of space until my newly planted trees get big enough to shade more of the garden.

Thanks, Gardengal and Luis!

I surely just HOPE that the ES will not die back too much - I believe that this location that I have is protected enough and it does seem to have a bit of a microclimate going on there (as you stated in another post). The thick layer of snow right now is actually providing good insulation for the roots, but the stems... sigh... I guess I just have to hope for the best!

Luis, I read somewhere before that Dirr was hoping to develop a pink Annabelle, so it is actually coming true then!? How amazing! It will look great next to my original Annabelles!!! Thanks for the great news!

P.S. Luis, I already have Limelight, Quick Fire, Pink Diamond, Pinky Winky, and Snow Mountain... :-) I just wished that I had the Pacific NW climate so that I could grow many more macrophyllas!!! Sigh...

That is right, I remember now. You still have Pinky Winky? I thought you were going to replace it (or was it move?).

Go here for info about the reblooming pink Annabelle: http://plant-quest.blogspot.com/

It is being introduced by Proven Choices (or is it Proven Winners?) and the breeder is Dr. Thomas Ranney of NCSU

Thanks for the link, luis! I would love to have this pink Annabelle in my yard!!! That said, there is something very special about the pure white snowballs of the original Annabelle, so I cannot decide which is more exciting - the new Incrediball or this Invincible Annabelle? If I had the space, I would love to get both! :-)

Anyway, Luis, you are right, I almost moved/gave up my Pinky Winky because it did not perform that well last year. However, I decided to give it one more chance, so it is still with me... what I had to do though (and it was painful to do so) was to give my Little Lamb away. I really did not have the space for it and it also looked out of place (with its droopy look) in my flower bed. I gave it to a colleague who is an avid gardener, so at least I knew that it went to a good home :-) Then that space was replaced by roses, which looked much better in the same spot.

I can't wait to see how these new arrangements will turn out in my flower beds this spring! :-)

It seems like all regulars suffering from the winter blues syndrome and wants to vent....:-)
Let me chime in as well.
It looks like we have an abnormaly cold winter this year, but I think we all were simply spoiled by previous abnormaly warm winters and forgot how to define our zones.
In my case (z6b) it's 0 to -5F and we had only two nights (so far) down to -2, while the vast majority of 'cold' nights was in low single digits and day temps rarely broke down below 10F. So, technicaly this winter still fits in 6b definition and so far I have no reason to worry about upcoming summer blooms. Yes, I know that H.aspera villosa and Little Honey most likely will not bloom, but rest should be OK.
As far as my experience tells me, bread-and-butter macs and most of serratas could take -5/7F (-20C) for a short period of time if they are completely dormant and not in a wind exposed locations.
Freeze-and-thaw (actualy in reverse order, thaw-and-freeze) cycles in spring are a major killer of flower buds that start breaking dormancy.
Therefore, while living all my hydrangeas unprotected for a whole winter I use some burlap wraping in spring if forecast says that below 0 is coming.

Ment to say, 'if below 0C is coming'

George, you got it! Yes, we are suffering from the winter blues!!! LOL!

I agree that we did have a few warmer winters in recent years, but still, when you compare the average temps, this winter has definitely been below average...

Anyway, I guess in a few months' time, we will have the answer as to how our dear macs have taken these big swings in temperatures, even to the limits of our USDA zones!

If my ES won't flower this summer, I will definitely not be kicking myself as to why I did not use burlap etc to protect them this winter. I have made the decision that all my plants need to be hardy enough for me NOT to have to baby them. This includes wrapping them with burlap. If they won't do well, then all I can do is to shrug my shoulders and say, "c'est la vie"! :-)

That is what I did with my gardenias, ostrich. It was a hassle to protect and unprotect. Specially when many persons kept saying to not protect in this zone. C'est la vie.

Now my temps are back up again in the 70s and 60s. Here we go againnnnnn

Hi everyone! Nice to see hydrangea enthusiasm on this cold winter day. I've been concerned about the beds since my region dealt with a nasty ice storm early December. We had virtualy no snow cover at the time, and I know that probably was the kiss of death for many of my flowers. I worry mostly about the roses and hydrangeas, though the PG varieties should be fine. We have fabulous snow cover now, but I fear the damage was done a while ago. =(

Here's hoping we all get lucky this spring and summer, and that somehow our plants didn't notice the bad weather. =D

Well, mehearty, guess what? We had PLENTY of snow here, so I am hoping that my plants were protected from the very low temperatures that we have had! However, I am expecting a lot of die back with my poor Endless Summer... so I am not anticipating a good show of blooms this summer... sigh... anyway, I will just continue to hope...

So, the snow is really melting away here, FINALLY! Trusting my luck though, we will probably have some severely cold temperatures coming here soon, with NO snow protection on the ground! LOL! Oh well, we shall see.... isn't it fun living up north, where we are so harsh and unfriendly to our poor macrophyllas!? LOL!

Oh Ostrich, you might be in for a great spring. Last year we had a ton of snow, and as the last of it was melting, I saw tiny green leaves emerging from ES under the snow! She was all smashed flat from the weight but rebounded like a champ. I probably got at least 50 flowers on her last summer. Snow is a very good thing. It's the best winter protection in the world. There's a chance you might be in flower central this summer. I'll look forward to your pics!