HOW far to prune.back the old flowers on Hydrangeas?
How far back should you prune back last years flowers on Hydranges plant. And the best time?
Ramsey County Minnesota
Thank you for writing.
You do not say what kind of hydrangeas you have and that can make a difference.
In general, the plant blooms on new, not old wood. Prune now and cut off dead blooms through the season.
Here is some good information from our colleagues in Anoka. https://www.anokamastergardeners.org/blog/2016/4/6/hydrangeas
This is a newspaper article for Minnesota. https://www.startribune.com/hydrangea-helper/62585782/
One final tip. You can, within the laws of physics, choose how pink or blue the plant is. It is not complicated. https://www.bhg.com/gardening/trees-shrubs-vines/shrubs/how-to-get-blue-hydrangeas/