Hydrangeas are not evergreen bushes. Because they are deciduous, the stems go dormant and loose all greenery in the Fall months.

Your winter weather is apparently too cold for the dormant stems and flower buds to survive. As a result, all growth in Spring originates from the base or crown. You then have to wait for new flower buds to develop, usually by June-ish.

In order to keep last year's stems alive and get blooms earlier, you have to winter protect the stems (the flower buds are located near the end of the stems). Search the forum for examples of overwintering techniques so the stems will leaf out and bloom after winter is over.

This post was edited by luis_pr on Mon, May 20, 13 at 13:06

Pickin Daisies,
I live outside Columbus, Ohio in true Zone 5. I have found the best way for me to overwinter hydrangeas (which I just did 2 days ago) is the following:
Step 1: See accompanying pictures. Clip off ONLY THE OLD FLOWER HEADS down to about 1 inch ABOVE (toward the end of the stem) the top-most pair of buds. In some cases, there will be a large bud at the END of the branch. LEAVE IT, do not prune those stems at all.
Step 2: Take some twine and tie about a third of the branches together tightly into a bundle. This is an easier job to do for 2 people than one. Use a bowtie like you would on a shoelace so it is easy to just pull an end the next spring to untie it.
Step 3: Take each bundle that is tied together, and gently, but forcefully bend it so the tips, and as much of the stems as possible are on the ground without breaking the stems at the base. It may take quite a force to do this, but it will happen without them breaking if you bend from the top of the branches downward toward the ground. Then, use something HEAVY and put it on the ends of the branches to hold them against the ground. While my photo shows to use firewood, this works best when it is split so there is a flat side. Otherwise, the spring in the branches will roll the log right off the end of the hydrangea stems. It always takes me several pieces of wood per bundle of stems to hold them down firmly. Trial and error will show you how much weight is needed.
Step 4: Then cover with some type of mulch. I have plenty of chopped up leaves (I use a lawnmower with a bag attachment to get my leaves off the grass and property each year -- they make GREAT mulch!) which I use then to cover the stems and wood to a depth of about 6 inches.

The reason this method works best for me, is that the ground provides extra warmth from below, and the leaves and wood on top provide insulation from the intense cold above. I do this for all my macrophylla and serrata type Hydrangeas (other types usually bloom on new wood only) usually in December in my area before the temps go below about 15 degrees, but certainly after they go completely dormant. I then leave them covered like this until well into spring (after the 20 degree temps overnight are gone), which for me is usually the latter part of April to first of May.
If you follow this plan, I guarantee you that your buds will survive, and you will have LOTS of flowers much earlier in the year (my Endless Summer and serrata cultivars are in bloom by early June). You will see the difference immediately when you uncover the plants in the spring (DON'T RUSH THE UNCOVERING, as you can uncover too early and get a hard spring freeze that will surely kill the buds you protected all winter!).
Good luck!

I am looking forward to my first winter and mop head Hydrangeas. Each bush is currently under 15 inches tall as I started them from cuttings. I predict next year they will be 30 to 45 inches tall then I can bend them down in hopes of protection of buds. My variety flowers on old wood so I am concerned to protect them this winter 2018/2019. My question today is...if the stems are bent to the ground like you show, will the bend downward contort the bush to stay in that position when you want the spring and summer bush to survive later on? After untying the bushes seems like they will want to flatten out and stay down at least some. My bushes are expected to reach 5 to 6 ft in mature height so it is going to be very interesting how they will survive in zone 5 or 6. I keep looking for helpful information as to what will help me out in the years to come to protect these from winter kill.

It sounds like your Hydrangeas are not winter hardy enough for your climate. You got two options. First one is winter protect them and you will have to do this the rest of the bushes life. https://plantaddicts.com/winter-protection-of-hydrangeas/ Other option is to replace them with more hardy varieties. Paniculatas are the hardiest variety.

For this year they are small enough so that you can surround them with a ring of wire fencing that is taller than the hydrangeas and fill it with mulch, leaves, straw or other insulating material. If you wrap the wire (including over the top) with landscape fabric or row cover, it will help keep the leaves/mulch from packing down low enough to expose the buds, but you can also just keep a bag of dry material to add as needed.