Spring flowers of fothergilla.Q: How far back can I trim 'Mt. Airy' fothergilla? When? And how can you prevent them from sending off suckers? I really don't want to remove them. I just need to know how to keep them under control.
A: You shouldn't have to give fothergilla any more than one bit of attention per year. You can sever any suckers and prune it at the same time -- ideally right after the plant finishes blooming in April.
For the young suckers creeping out from the perimeter, just take a shovel and cut through them. Most of the time, they'll be rooted, which means you can transplant them or give them away, if you want.
Cut them when young and they'll come out easily. The other option is to prune them off with loppers at ground level if you can't shovel through them.
Then use shears, pruners or loppers to reduce the size of the plant by up one-third. I prefer pruners and loppers. They give a more natural look than shears.
With that game plan, you should have no trouble keeping 'Mt. Airy' to a nice size of about 5 feet tall and 4 to 5 feet around, which is the size I keep mine. I spend about 5 minutes all year on maintenance of it.
Fothergilla hardly ever run into any bug or disease problems (no spraying), they're drought-tough once established (no watering) and they get along fine in reasonably decent soil (no fertilizing). So I definitely wouldn't recommend getting rid of them.