Flowering this week at JLBG is the little known, woody, vining Hydrangea ampla. Originally discovered in Sichuan, China, it has recently been discovered and collected in Northern Vietnam, often under the name Hydrangea megalocarpa, which is almost certainly the same plant. Our specimen, from an Ozzie Johnson/Scott McMahon collection, has thrived with no damage since 2010. Before the genus Hydrangea was recently reunited, this belonged to the genus, Schizophragma.
Since this post is about hydrangeas, may I ask a question about my Limelight hydrangeas (Hydrangea paniculata)? I think I saw in one of your videos that the best way to prune them is to cut them back very hard in early March (I’m in Raleigh, NC). Mine are planted under windows, so I definitely don’t want them getting too tall.
I’m wondering if I haven’t been pruning aggressively enough, because the blooms seem to be getting smaller each year. Would cutting them all the way back to the ground produce larger flowers, or is there a better approach for keeping them compact while maximizing bloom size??
Hydrangea paniculata should never need a cutback if it’s planted in the correct location. This is a large plant that shrub to 8′ tall x 12′ wide that should never be planted under a window. They will reflower if cut to the ground, but the stems will be long and weak, and have trouble supporting the flowers. A selection like Hydrangea arborescens ‘Wee White’ would be a much better choice.