Please remember I am not an experience Gardner but when do I need to start?
I intend to be very radical this year as my garden is very overgrown so silver/grey plant is spreading like wild fire
I have a hyderanger I pruned drastically last year that has come back on abundance but not a bloom on it
I have lavender and holly that I had not intended to touch
And finally lilac and some other bush/shrubs
Leave the hydrangea until the Spring, we prune ours back really hard at Easter then the sap is rising and it springs into life. It's a mass of flowers at the moment.
what's this silver-grey plant you mention, is it a shrub?
We cut back other shrubs any time, we are pruning the dogwood now.