Hello,

I need a little more information to make a diagnosis.   Could you take a couple of closer in pictures of the leaves that are out as well as the stems?  Do you know what type of hydrangea it is, and are the other two the same and are they planted near this one?  Do you water, fertilize, or prune your plants, and if so, how?  What side of the house is it on/how much sun does it get?  Finally, did you notice anything strange or different about the leaves on this plant the last year it did leaf out and bloom well?

It could be anything from a root problem from overwatering to a disease to dying off because of many years of lower than ideal rainfall.  If you send in the above information I'll try to pin it down for you.  Thanks!

You have clearly been taking good care of your plants and have them in good growing conditions in your yard as far as sun exposure goes, so I'm going to bypass all the usual suspects and go through a list of other possibilities.  (I don't think adding that amount of lime should have hurt them if they were already healthy even though it may have happened at the same time as the problem showed up.)

Sometimes this sort of thing can be caused by herbicide damage, perhaps volatilizing and drifting over from a neighbor's, but if all the surrounding plants look fine, that seems unlikely unless it hit at a time when only your hydrangea had growth on it.  That could have happened a couple of years ago and the plant struggled on for a while but isn't winning the battle.  If that's what happened, you could dig this one up and put another hydrangea in its place.

It looks like winter cold damage, but we didn't have any really cold weather this year (or last year either if I remember correctly) so that shouldn't be it.  We have had some hot and especially dry weather recently, though.  The leaves on the old wood on my hydrangeas look kind of puckered and weird this year (very similar to the leaves on your close-up picture) and I have put it down to drought and heat as they were leafing out despite watering them.  I think I've seen a few other Hydrangea questions go by this year (answered by other Master Gardeners) that show similar leaf problems so an environmental problem seems likely.  A lot of older area conifers have been dying due to prolonged drought, so it's likely other woody plants are also being affected even though the damage may not be visible for several years.  Here's some information from the University of Massachusetts on symptoms of long-term drought in shrubs.  If this is what happened, I wouldn't replace it with another hydrangea without changing your watering routine or it will just happen again.  You could go with a type of plant that is more forgiving of drought.

One difference I see is that there doesn't seem to be any new growth coming up from the crown in your pictures.  When you pruned last year did the canes still seem to be alive (a little green just below the outer surface)?  You can try cutting several back and checking or you can scrape away the outer surface to see if there is still some green there.  If there isn't, those canes are dead and can be cut all the way back (make sure to disinfect your clippers afterwards).  There's a possibility that your plant is suffering from root rot, which actually can take hold in drought-stressed plants as well as plants that get too much water without good drainage.  If you look in this link from University of Connecticut and scroll down a little they have a picture of a plant with root rot that looks somewhat similar to your pictures.  If you find that most of the old canes on your plant are indeed dead and there is no new growth coming up from the crown, I'd suggest going ahead and digging it up.  When you do, take a good look at the roots and see if you can see either the white mycelia mats or black rhizomorphs of Armillaria root rot or if the roots are discolored and limp or mushy.  If you think that's what the problem is, don't put in another plant that is susceptible.  Here's  list of Armillaria resistant and susceptible plants to help you choose.  And here's one for Phytophthora.

The only other possibility I can think of is that another plant or tree has grown up over the years to the point that it is competing with your hydrangea for water or nutrients, but I don't see anything like that in the pictures. 

Regardless, I think this plant is probably done for.  Keep a very close eye on your other hydrangeas, especially the one that is nearby and if you see any signs of trouble on the leaves or flowers that could be an indication of a disease.  If they continue to look good, it was most likely some sort of environmental problem with that particular spot that stressed the plant which then died from that or made it susceptible to a fungal problem.  Sorry I can't be more definite with an answer!