Wait until the end of this month and then remove any woody stems that do not show any buds or leaf growth right down at the base of the plant.

Have patience. Wait until the end of May if located in the south or wait until the end of June if located in the north/in July if near Canada. I just had a long sleeper mac that woke up this week in my z8/Tx, several weeks after the one nearby; very lightly scratch the base of each stem to confirm the live status and see if you "see green"; prune from top to bottom in tiny increments (1/4"? 1/2"?) until you "see green" or get to the bottom.

I'm not sure what zone I am in. I'm in NYC

For NYC, the average date of last frost is the 3rd-4th weeks of April and the forecast through the 17th looks favorable (no frost). Wait to prune until the end of June. In your USDA Zone 6b, I would protect the ends of those stems from frost/freezing temperatures to encourage reliable spring blooms unless this variety reblooms.

Thank all

The previous advice was provided by someone who is very unlikely to have had a successful experience growing bigleaf hydrangeas, especially old wood bloomers. Cutting back each spring is highly unlikely to generate many, if any, flowers. That is just the way these plants grow and pruning of any kind - other than deadheading - should be approached with a degree of caution. Or one might never see these plants flowering.

WAIT to cut back until after your last frost date and then only remove woody stems that have not produced any leaves and cut back those that have partially leafed out back to where new growth is emerging. Otherwise, NO pruning at all!!

Depending upon where you live in NYC, your growing zone is 7a or 7b. You can google US growing zones to see where you fall. I found a site that shows NYC, treevitalize.com

debra

I would be very surprised if any of the canes that look very dead produce any blooms. You have too much growth from the ground for leaves to emerge now from the canes. But, it won't hurt to leave the dead looking canes. They'll eventually be overgrown with new growth and break off on their own.

It is never a good idea to leave dead wood in place over the growing season. It can harbor disease pathogens and insect problems.

I did, indeed, prune the dead branches. I will update when the results are in. Thank you all

We're dealing with a hydrangea. There's no wood. There's no threat of something falling off and killing something, I doubt it would even kill an ant, Almost everyone leaves the old canes on. Look around your neighborhood. I do it all the time because it's unnecessary to cut them out. It doesn't hurt the plant.

LOL!! There most certainly IS wood! Hydrangeas are shrubs - woody plants that have a permanent above ground framework. While not much risk of any limbs falling, leaving any deadwood in place is not a great idea for both looks and plant health.. Not everyone leaves old canes intact. They make the plant crowded and congested and can host disease and insect issues. Any dead wood - unproductive stems - on hydrangeas should be removed annually

The old stems from the previous year aren't wood. They're like straw. I can pull them off with no cutting. And technically not everyone leaves them on, but almost everyone does. They fall off on their own over the summer. And I've never had a problem leaving them on. I almost always do. You're making a mountain out of mole hill.

" The old stems from the previous year aren't wood "

Sorry but that is just wrong!! They most certainly are woody and stating otherwise is a reflection of a major lack of botanical understanding. Hydrangeas are caning shrubs, constantly generating new stems from the root crown. If you do not remove the dead or nonviable ones, you will wind up with a big congested mess! Routine garden maintenance is rarely considered as slight as a mole hill but it is far less than a mountain!!

UPDATE Last month I asked if I should prune the dead branches off of my hydrangea. There was a number of opposing answers. I opted to prune the dead branches. I think I made the right call, as evidenced in attached picture. I do, however wish the blooms were the deep blue that I so love. Thanks for all the advice.

You made the right choice......some of the responses were just wrong :-)

The blue color on mophead hydrangeas is a function of soil chemistry - an acidic soil pH and available aluminum. Although it will not make an appreciable difference this season, dosing your plant with aluminum sulfate (aka hydrangea 'bluing') should provide the right conditions. Just follow the label directions.