Q.Hydrangeas leaves wilting
I have had a number of hydrangea plants in my back garden for about 5yrs all doing extreamly well on the other side of fence where they are planted is a tree which has got bigger every year , all of a sudden this year one hydrangea started wilting then dieing of eventually went brown and whole thing died then it happened to the one next to it then the next one and niw the 4th one has the same ive always watered well and fed on accasion I don’t know if they all have a disease can i save my other hydrangeas thankyou , i live southeast London
Your plant may have either received too much water or not enough. Your Hydrangea may have suffered some root rot or die off of roots.
When this happens the plant cannot take up moisture.
Dig down into the soil to check how much moisture is in the soil.
I don't see any evidence of disease on the leaves such as Grey Mold.
https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/growing-hydrangeas-hydrangea-care-guide.htm
https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/drooping-hydrangea-plants.htm