Bonsai Development Series #25: Pruning exposed root pines – Bonsai Tonight

Some of my exposed root pines are close to seven years old. They have long sacrifice branches to help thicken the roots.

Although the fastest way to thicken the roots will be to let the tree grow freely all summer, I often prune this time of year to improve the branch structure. As an added benefit, pruning reduces the space each tree takes up which makes room for more trees!

In general, I want the sacrifice branches to grow quickly and I want the future primary branches (the branches that emerge from the trunk) to grow slowly. To accomplish this, I thin the sacrifice branches by removing all but the strongest shoots, and I decandle or remove overly vigorous primary branches. Here’s what this looks like.

Exposed root red pine with sacrifice branches

After pruning – 26″

As you can see from a close-up, I kept very little foliage where the future primary branches will develop.

Close-up showing the area where the primary branches will grow

Here’s the same process on an exposed root black pine in training.

Black pine

After pruning – 28″

I removed more of the sacrifice branches on this tree because many pointed downwards after pulling the trunk closer to vertical. By keeping the main sacrifice branch upright, the tree takes up less space.

Close-up showing the future primary branches

I keep different numbers of sacrifice branches depending on how a tree grew the previous season. Here’s an example of a tree with three small sacrifice branches.

Red pine with three sacrifice branches – 21″

I’ve always enjoyed this work as it’s quick and it provides a window into the future design of the tree. I do similar work on all of my five-to-ten year old pines this time of year, whether or not they are being trained in the exposed root style.

And unlike my refined pines, these younger trees will receive fertilizer throughout summer. While it’s common to stop fertilizing pines that have been decandled, internode length isn’t a major concern at this point so I make sure these trees get lots of fertilizer to keep them healthy and encourage rapid growth.