Q: I’m having trouble with my hydrangea trees. The branches sag too much. This past spring I pruned them down to practically nothing.They continue to grow massive flowers, causing branches to sag and break. Any ideas how to maintain a nice shape?
A: PeeGee hydrangea, Hydrangea panniculata ‘Grandiflora’, is often seen trained to be a small tree. It can be spectacular when blooming in early August.
The best time to prune is December-February.
If yours is overgrown and unpruned, follow these steps:
1. Decide how tall you want your bush/tree to be when it blooms. Typical heights are 8′ – 10′. Since you’ll get 3′ of new growth each year, cut the height of the bush down to three feet below where you want the top to be.
2. Once everything is cleared away, select one to three of the most vertical trunks and remove all other vertical stems except them. These will be the trunk(s) of the new tree.
3. On each small limb coming from the trunk(s) make a cut just beyond the first pair of buds. New growth coming from those buds will leaf out and flower in August.
4. Each winter thereafter, remove sprouts at the base of the tree. Cut back small limbs on your main trunk(s) to the first pair of buds. Your hydrangea will remain about the same size and will flower reliably.
5. Don’t fertilize much. Once in spring is enough.
This guy’s three videos seem to make a lot of sense: