I have three hydrangea plants alongside other flower plants, few weeks back i noticed the leaves on them were all wet mushy and gone all purple and now they seem to be dying. Anybody know what could be the cause? I think there could be possible two reasons, one night the temp was down to 0 degrees so maybe due to frost? but few doors away one of my neighbors hydrangeas are doing fine although they are alot bigger than mins, I only planted mine last summer. The other reason could be I used seaweed fertiliser on all of the flower plants including these. Any ideas?