We have a small garden with pre-existed hydrangeas (left from previous owner) - unfortunately, I have no idea what variety they are. All I can say it's 5 feet tall, and last year there was no blooming, so this year I decided to give them a boost. Pruned the old branches last autumn according to guidelines and considering feeding them. So I have a question - which fertilizer do you use for hydrangeas? And why? Also when it's better to apply (through the season or at spring + late autumn only)?