I usually start thinking about pruning and partially defoliating Korean hornbeam in May. It’s around this time of year that the spring growth hardens off and shades out the interior branches which makes it a good time to prune.

Dense foliage on a Korean hornbeam – May 12, 2021

For the last few years, I partially defoliated this tree by removing most of the leaves from the outer branches. As a result, the tree has become less and less vigorous in spring.

Since the new growth was modest this year, I decided to keep more foliage than usual so I reduced new shoots to two leaves and only removed the largest leaves from crowded areas. The idea is that by preserving more foliage the tree doesn’t need to dip into its reserves as much this summer which should make the plant stronger through summer and fall.

After cutback – 18″

As trees mature, the work we do to maintain them may change along the way. Now that this tree only produces a modest amount of growth in spring, I don’t need to do as much work to keep new growth in check during the growing season.

I’ll decide how much to prune through summer and fall based on how much the tree grows in the coming months.