No worries, I did the same thing my first year too. Do you have a picture of them? FWIW I just left mine and they came through fine.

SCG

The fertilizer (slow release) shouldn't have hurt your hydrangeas.

When you say horrible what does that mean? Are they dead or look close to death? Did you keep them watered religiously for their first year in the ground?

Certainly watered them constantly. They just look unhealhy. The flowers shortly after planting turned to these brown globs. The leaves are still green and look good, not as full though.

Too much water.

The plant its self looks healthy . I would just leave them in the ground and let them continue to settle in .

Looks good to me too - first year? What do you see as wrong? Flowers will fade so you either leave them on or cut them off.

It is the first year. They havent increased in size, which I thought Limelights are fast growers. What flowers were there never faded to the green and then dark rose. They just all turned to that brown color. Also the leaves are not as thick as they once were. If it doesn't look like anything to worry about then, I will revisit next year. Hope they come up good, strong and healthy.

The first year it should just be putting down roots - don't be concerned about a lot of top growth the first year - just that it is green and healthy looking. Once it is established, watch out! My biggest one is 4 years old and is over 8 feet tall and at least that wide. I started with a one gallon sized plant.

Not sure Limelight fades to dark rose - at least I have not noticed mine doing that - maybe a light green.

Here is my biggest one about a month ago.

As the old saying goes .
First year sleep
Second year creep
Third year leap
I try to keep that in mind when I am waiting for a plant to mature.When we were all buying limelights a few years ago here on garden web alot of us noticed they shocked easily during transplanting from a pot to the ground. More so than most hydrangeas but they always seem to rebound really well.

Did you water them from the top or at the roots? It looks like you sprinkled heavily from the top in very humid weather, maybe even watering around noon. Top watering may seem natural, like rain but if the sun is shining, you are cooking the flowers which hold a lot more water than the leaves and are more tender than the leaves. They don't get a chance to dry out so the water heats up...a lot.