What's This

[muddygirl]

What's this, and how bad is it? I'm not seeing anything with a quick Google search :/ appreciate some help...

[applestar]

I suppose hydrangea experts might be able to tell at a glance what you are talking about, but it might help them to help you to provide a bit more detail like where you live, what weather and climate you are experiencing now, how old this plant is, etc.

[rainbowgardener]

A farther back picture with more context might help.

The bottom picture looks like branches coming from the base of the hydrangea, with buds on them.

[imafan26]

It might be a canker.

[luis_pr]

Yeah, it does look like canker. Basically, a dead section of the bark or the whole stem. Caused by bacteria or some fungus. Will infect the whole shrub so you may want to try cutting the stem all the way to the ground and if it returns, you will have to extract the plant, roots and all, and dispose in the trash (not in a compost pile). May have entered in that location when the stem had an injury (pruning can also let the bacteria "in" if the bacteria is around already) and-or if the plant is "weak" due to moisture issues/etc (hard to tell 'after the fact' how this bacteria got inside the stem of course).