For the last few years, I’ve taken a simple approach to refining a dwarf wisteria (Millettia japonica ‘Microphylla’). In May or June, I reduce long shoots that extend beyond the desired silhouette. The process looks like this.
Dwarf wisteria
New shoot
After reducing the shoot
After cutting back to 2-3 leaves per branch
This approach is good for balancing vigor among strong and weak branches, but it does little to promote ramification. I also find that small interior branches can die off during the growing season due to lack of light.
As an alternative to this approach, I’ve tried cutting larger branches in spring (see “A dwarf wisteria bonsai” for an example). This approach is good for preserving interior growth, but because it’s hard to see the branch structure when the tree is in leaf, it’s hard to identify the best places to cut.
This year, after cutting back to 2-3 three leaves, it was clear that the foliage was still too dense to allow light into the tree’s interior. Not wanting to thin the tree by removing larger branches, I thought I’d try reducing the leaf size by cutting all of the leaves in half. The idea is to preserve as much fine growth as possible while letting light into the tree’s interior. Here’s what this looks like.
Millettia foliage
After pruning leaves
Leaf pruning half complete
After leaf pruning – 13″
I haven’t tried this approach before so I’m curious to see how the tree responds. In the meantime, I plan to let the tree grow freely until fall at which point I plan to prune and possibly wire some errant branches.