How do I get my hydrangeas to bloom?
I mistakenly pruned the old growth back not knowing these were the old fashioned kind.
Suggested Project Book
http://homeguides.sfgate.com/hydrangeas-bloom-after-being-cut-62711.html
Looks like you will have to wait until next year. Because they do indeed bloom from the last year's growth, there is nothing that will make them bloom this year. Sorry.