Waaay back in November, DH and I were putting the garden to bed. I asked DH to cover the hyds with black garbage bags and weight the bags with stones or bricks. DH decided that it would do a thing to protect the hyds (7 of them, 6 of which were planted only last summer). Will they live? Will Nikko Blue, covered in buds, survive the freeze we are in for?
Tell me my hyds won't die
If they're not covered and you're in for cold weather, it's not too late, you could put something over them now (people who live in climates closer to yours can provide better advice than I could on what's the best thing to cover them with). Or if you don't have anything to cover them with, they'll still probably survive, but you could lose next year's flowers if the buds freeze (this is why people in zone 5 often have trouble with hydrangeas, the buds freeze off over the winter and then they don't get any flowers the next year). I'm pretty sure Nikko Blue blooms on old wood so its flowers are at risk if your temps are going to be colder than normal. You didn't mention what your other cultivars are--if they bloom on old wood they're in the same boat but if they're ones like Endless Summer that can bloom on new wood then the flower buds freezing doesn't matter because they can make more in the spring.
Zone 8b, Heat Zone 9, Southeast, TX
I have in ground 3 hydrangeas which blooms on old wood. Temps. have dipped down to 20, 30 degs. I covered my buds with a sheet and then placed a plastic leaf bag over the sheet to keep the sheet dry. I remove this covering during the day when my temps get around 40, 50, 60.
I hope I have flowers in May. If not, I plan to dig them up from the ground and plant in big pots so that I can overwinter them in my greenhouse.
I purchased a potted Endless Summer in 2006 which blooms on new wood. It is still in my greenhouse.
Our Texas weather swings from one extreme to another in a very short time span. Most of my plants are in big pots and overwinter in greenhouse.
I hope the lady in NJ has blooms but I would not bet money on it. I've read that plastic against your plant leaves damages it considerably. Endless Summer blooms on new wood. This hybrid may be your best bet to prevent having no blooms at all.
Best of luck to you and your hydrangeas.
I tried protecting my macrophyll's here but never got any better results. Most of the buds dieback and I get a flower or two. I only buy panniculata's now.
I think the macrophylla's, even the ones that bloom on old wood are usually OK in zone 6. I used to live in zone 6, and although I didn't grow hydrangeas many of my neighbors did and theirs generally bloomed fine, I think it's when you get to zone 5 that you start to have real problems. (I lived there before the days of reblooming cultivars like Endless Summer so it was all the old kind that bloomed on old wood). I'm not sure if they protected them or not, I don't remember seeing stuff over the plants in the winter so I don't think they did.
As far as the plastic against the leaves--that is a problem in warmer zones where you're trying to protect evergreen plants from frost, but in a colder climate hydrangeas will have lost their leaves by this point in the year so I don't know if it's a big deal or not, seems to me I remember some other people from colder climates talking about using plastic successfully to protect their hydrangeas (although putting straw or some other sort of insulating material in there will provide better protection).
Sudie--if you're in zone 8b, your hydrangeas shouldn't need protection in the winter at all, and you definitely shouldn't need to put them in a greenhouse. I don't think I've ever heard about anyone in zone 7 and warmer having problems with buds freezing, those complaints are common in zone 5 and definitely can happen in zone 6, but in zone 8b your hydrangeas should have no problem handling your coldest weather.
Thanks to all. 1 paniculata, 1 Forever & Ever Radiant Red (should bloom on new wood), Nikko (which bloomed on new wood last year; apparently there's a sport of Nikko going around the northeast that blooms on new wood and I may have gotten one, even though it was labeled Nikko Blue), the rest macrophyllas- Preciosa, Blue Bird, Amethyst, and I am blanking on names already. If I lose anything, I will be philosophical, and replace with remontant types or paniculatas that I like (the one I have is Lime Light).
Other question now that some experts are here- over on the roses forum there's a thread about adding Epsom salts around the bushes come March. Do hyds like that too? I knew pelargoniums like a lot of magnesium, never knew about roses, now I wonder if a lot of plants like the extra boost on a schedule. Does anyone know? If this should be a new thread, LMK and I'll start it.
Your paniculata and the Forever and Ever should be just fine as well as Nikko if it blooms on new wood; the other macrophylla's may lose their flowers. But unless the temps are getting much colder than the typical lows for your zone, you may not lose all the flowers and I think the plants themselves will survive (especially the paniculata--it's hardy to either zone 3 or 4).
Sorry don't know anything about the epsom salts.