How to prune an old leggy mophead to promote fullness/new growth?
I have a few 20 year old Mophead (look almost identical to pics of Nikko Blue) hydrangeas that have gotten leggy and thin. They each have a few old stems that send out new shoot and flowers every year and a couple of new stems, but they are much less full then they used to be. What should I be doing pruning and fertilizing wise to get them back to being dense? I also wouldn't mind controlling their size, even if that means cutting them down to the ground and missing a year of flowering. I'm ready to be drastic here!
- They don't get a ton of sun. Mostly shade until late afternoon.
- They bloom at the end of June here in Maryland. (Will probably be earlier this year since tulips are already starting to come up and forsythia has started to bloom).
- I usually wait until early spring when all frost chances are gone, and buds are starting to leaf out. Then I prune each stem down to right above the healthiest buds...usually the 2nd or 3rd bud down.
- I've been afraid to cut too many of the really old stems down to the ground, even when they aren't producing many buds.