How do you fertilize hydrangeas?
This year, I was trying to be a "really good" gardener, so, for the first time, I gave all my hydrangeas a handfull of slow release fertilizer. And, for the first time, I got virtually no blooms at all. My Endless Summers which have always bloomed non stop, bloomed once, and not again at all until just recently (I assume the osmocote has worn off by now). My blushing brides didn't bloom at all, except a very few early on. Also, the leaves on many of the plants developed black spots early on, but which have been replaced by nice green leaves since late summer.
I had virtually no blooms on my old fashioned ones either.
I know I have read that hydrangeas like commercial fertilizer, but this experience makes me question that wisdom. What is your experience?