It is possible that drift of Round Up or other insecticides could have caused problems. Without someone to describe what happened to the leaves as they died, it is hard to verify this was a cause though. Just as bad is lack of water in the middle of summer. Depending on conditions, things could go bad in the period of a week or slightly more.

Lack of water can make the plant abort the blooms first. You can see changes in them turning brown and such. The leaves go next and they brown out from the edges inwards. Initially, some leaves may turn yellow and fall as moisture is lacking but, if the lack of soil moisture is bad enough, they will brown out instead.

As long as there is some green left in the stems or leaves, they will recover. I have one that lost all leaves, stayed dried out thru the Fall and Winter and leafed out in the Spring.

Maintain 3-4" of mulch and water the soil with 1g of water (newly planted shrub; use more water for established larger ones) early in the mornings. Water when a finger inserted into the soil to a depth of 4" feels dry or almost dry.

If part of the shrub is affected onn the same side as the lawn, there could have been chemicals used there but, determining if that happened is hard and requires observing the area around the plant for things that do not look normal, smell out of place, installing cameras, calling Detective Columbo, etc LOL!

I have been looking after this small hydrangea for 3 years as a cutting and it has been doing very nicely without flowers. The new leaves are healthy but as they get bigger the larger ones and some of the small ones are going black around the edges and creeping inwards. I have taken off the bad leaves hoping this would make it come alive again. After all this time I don't want to lose it. it was a cutting from a friends garden and it was bit in half by a squirrel which I managed to save into 2 plants. The top half produced a very tiny flower this year but has since died I think. I have re-potted them but the one that is left is the bottom half of the plant that was bit by the squirrel. I felt the soil but it seems too wet. I thought the leaves drooped when it was dry. There is new foliage coming up bright green. Must keep it going. Any advice.

Need pictures, please,

Many thanks for your replies. We establsihed that someone had chucked Round Up over the garden. Lawn is still recovering. I kept hyrdrangea well watered and the good news is that she is starting to recover with new shoots. I think whatever it was killed the blooms and flowers. I think I managed to remove affected soil etc before any further damage occurred.
Edit to add that this area of garden is fairly shady and rear south facing garden is subject to far more sun. Lawn and foliage everywhere else is normal.

This post was edited by Edythe01 on Sun, Aug 17, 14 at 8:35

This was how it looked when I returned home from work. It was in good health (as all other plants in garden) when I left. All plants had been watered regularly. All were healthy (and still are - with the exception of this one) I had to attend conference for a couple of days - and we think the person attacked the plant soon after. Blue flowers are on same shrub and were not hit by the Round Up or whatever was used. I think I did the right thing by clearing out the soil and stripping off the dead foliage. The affected part of the shrub is now showing new shoots as per photo posted earlier! I am hopeful of full recovery - but wonder if there is anything else I should do to help its recovery.