I would monitor the soil to make sure it is draining well and not starving the plants of oxygen and causing rotting. After a while, this constant amount of wetness can produce root rot. Since you have had two plants mysteriously affected, I would ask your Agriculture Extension Office to process a soil test (to look for mineral defficiencies or high levels of minerals/salts/etc). I would also send them samples of affected blooms/leaves in a sealed transparent plastic envelope for analysis. They should be able to detect problems with Pseudomonas solanacearum (bacterial wilt) abd Phytophthora root rot.

The shrub on the right appears as many hydrangeas do when they begin to go dormant but I do not know if that look is normal in early September where you live. I usually see that in November-December instead.

But purple leaves are also a sign of mineral problems, such as phosphorous/potassium/magnesium deficiencies. A good soil test can help detect magnesium deficiencies, phosphorous deficiencies or high levels of pottasium (sometimes associated with low levels of magnesium).

A finger test can be used to determine if the soil is not draining well and acting like a bath tub full of water instead. Insert a finger daily to a depth of 4" or so early in the morning and determine if the soil moisture cycles between periods of almost dry to moist to wet and back. If it stays wet for a day and you cannot find an explanation (for example, it recently rained) then investigate water draining issues further.

Here is a link with a better test if you are interested:

http://www.ehow.com/how_4543171_test-soil-drainage.html

Lastly, this coloring could be normal. For example, Preziosa, a cross of macrophylla and serrata types, does this leaf color change often late in the growing season. Plum Passion has purplish leaves too.

Luis

Hi Luis,

Thanks for the feedback. I have added a photo of t he roots this time as I could see how to add 2 photos. Re the soil test I will have a go at this. I have my own well water supply and have to get that tested annually. That always shows high iron content and slightly over borderline magnesium which my water filtration system handles, so I dont think that element is the issue but the volume of rain here over the past couple of years has been immense and severely affected most lawns in the area. These particular hydrangeas are located at the lower end of the garden so I am guessing this is the main issue. Even up to June the water oozed up when I walked on the lawn. I have recently installed a new land drain which should help going forward and we have had a dry summer. I will look to replant with new ones in the spring and see what happens.

Yikes, being clumsy myself, I would have used the services of a landscape company to reroute all the water elsewhere somehow, like you did with the land drain that you refer to.

Any time that you walk on the ground and water oozes up, that would not be good for hydrangeas. An oakleaf hydrangea, being extremely sensitive to wet soil, would have petered out in no time at all! Good luck with the land drain, allenj22.