I have a patch of soil facing southwest. I have tried to grow hydrangeas without success. 2 metres away are photinias doing beautifully. I tried to test the pH; however, got no reading. The soil in that patch is clay like but 2 metres away it is beautiful.
Soil for Hydrangeas
Certified GKH Gardening Expert
Hydrangea require a rich, well-draining soil and clay soil doesn't exactly fit that bill. You could try amending the clay soil where you are trying to grow hydrangeas. The following articles will instruct you on how to do so: