Always wait till the plant has gone completely dormant, meaning that all the leaves have dropped. The plant uses the leaves to continue to store energy till then.

In in your area that will be somwhere around Thanksgiving time. typically when I do my final fall cleanup is when I winter protect.

Guyground,

Hypothetically speaking, lets say in a couple of days my area is expected to get a frost. Plant is still 100% awake (leaves are still the healthy green color). If I don't protect it, won't that kill the flower buds?

I've been reading that if you get a unusually early frost, instead of doing the full blown winter protection, you can lay burlap or some other kind of sheet over the shrub the night of the frost to protect it temporarily.

Once the frost conditions have cleared, take the cover off, let the plant continue to go dormant. once fully dormant, do the full winter protection?

Luis,

Cool. That was my initial thought as well. Thanks for the input.

Wait till full dormancy , all the leaves drop. Frost is ok. It will never get cold enough in November to kill buds.

OK, thank you guyground. Out of curiosity, what temperate kills flower buds on Hydrangeas?

Maybe below 20

Hey Luis,

You mentioned you didn't have good results with burlap? Can you elaborate?

I was using burlap to protect some gardenia bushes in winter but it did not help and the foliage always suffered so I stopped the practice.

The main reason people use burlap for early frosts is they want to squeeze out a little more time for their flowers. So they will place burlap overnight over the plant when early frost is predicted and remove it during day when the temp warms up getting a little more time for their blooms.

Using it in that manner is not part of a winterization strategy though, its a way to have blooms for just a little bit longer by offering some protection.

Macs failure to bloom due to cold damage is the result of three different factors:

1. Early fall frosts...before the plant is fully dormant.
2. Excessive and prolonged cold winter temps. Mid teens are not uncommon in my area from time to time but seldom last more than a night or two. And I have never provided any winter protection for my plants and they never fail to bloom. But were we to receive temps that hover around 20 and into the teens for more than a few days, I would.
3. Hydrangea macrophylla responds very rapidly to warm spells in winter and early springs by breaking dormancy and starting to push new growth. But these early warm periods can be followed by more cold weather and/or late frosts and that's when the damage can occur.

Out west, we have pretty mild winters and sometime no frost until December or January. And once March hits, temperatures creep gradually upwards with no late frosts or hard freezes. But the eastern half of the US does not have the same stability of temps (except for some beachside locations) so the early fall cold spell and the late winter/early spring thaws/warm spells followed by freezing weather are what cause the majority of the problems with flower bud damage.

Thank you GardenGal!

Boy does summer fly. Can't believe I'm figuring out how many kale plants I will need already