One of the most enjoyable aspects of owning a bonsai tree is the artistic part — pruning and styling. Sure, it’s fun learning how to care for your bonsai, and understanding the fundamentals of watering and fertilizing are essential to its health. But let’s face it … getting your hands dirty and working on your tree is the real joy. In this article, we’ll go through a crash course in pruning juniper bonsai and learn what to do, and what not to do, with your tree.
Why Pruning Juniper Bonsai is Important
As it turns out, chopping branches and foliage off a tree isn’t just about creating a visually stunning bonsai. There are also some very practical reasons for pruning. For instance, we might prune to allow more light to reach deeper into the structure of the tree.
We can generally categorize the practice of pruning juniper bonsai into two buckets:
- Maintenance Pruning
- Structural Pruning
If you’re working on your first tree, you’ll probably be closer to the “maintenance” mode than the “structural” mode, so we’ll focus on maintenance in this article, and cover structural pruning in a future article.
Goals: maintains the aesthetics of the tree, promotes the strength of the tree, encourages new growth.
When: during the growing season, spring through early fall.
In maintenance pruning, we are essentially “thinning out” the foliage and selectively choosing what to keep and what to cut off.
When we start pruning juniper bonsai for this reason, we’re interested in removing the following types of foliage/branches:
- Foliage that has emerged from the crotch of a branch
- Foliage which has grown too long and extends beyond the silhouette of the tree
- Secondary and tertiary foliage/branches that are growing straight up, or straight down
Juniper Bonsai Pruning Techniques
Before we start cutting, let’s take a quick moment to understand where on the tree to cut. We don’t want to inadvertently weaken the tree while pruning it, so it’s important to understand where the tree gets its energy.
Junipers get their energy from their growing tips. Look at any juniper during the growing season and you’ll notice that the tips of the foliage have turned vibrant green. Greener than the rest of the plant. These are growing tips.
We don’t want to remove too many of these tips, as it will reduce the strength of the tree. Instead, we want to selectively find growing tips that have become too long, and trim back to the next set of growing tips, thus leaving plenty of tips on the branch to preserve its energy.
This foliage extends beyond the silhouette of the tree, so it should be removed. Notice that we’re only removing the longest portion of the foliage with our bonsai shears, and leaving plenty of growing tips on the branch.
We want to avoid “hedge pruning” bonsai, especially junipers. This method removes too many growing tips.
Don’t trim like this.
Pinching Juniper Foliage
It was once common place to “pinch” tender juniper foliage as it emerged. You may have heard of this method and asked yourself “should I pinch my juniper bonsai?”
On the surface, it seems like a reasonable way to clean up the silhouette of your tree. But many contemporary bonsai artists would say “No! Never pinch junipers!”
The most widely accepted way to prune your juniper is to allow the foliage to grow — to provide energy and strength to the tree. Then, if the foliage extends beyond the desired silhouette of the tree, we trim off the overgrowth with a pair of sharp shears, as shown previously in this article.
Maintaining Juniper Foliage
Consider a young juniper bonsai tree. Our goal is to create lateral branching on the tree.
To understand what lateral branching is, try this: hold out your hand, palm down, and spread your fingers apart. Now imagine your hand is a branch. You’ll notice that none of your fingers are pointing straight up or straight down. All of the branches are growing laterally.
Why is this important? Because lateral branching allows light to penetrate the tree and reach all of the foliage. We don’t want foliage die-back due to lack of sunlight.
Start at the base of the trunk and follow it up to the first branch. This is a primary branch.
Off of the primary branch, you’ll find many secondary branches. These may be young shoots, or they may be lignified (hardened) secondary branches. This is where we’ll begin our pruning.
If we’re going to create lateral branches, we probably don’t need secondary branches that emerge from the bottom of the primary branch and grow straight down. Those can be removed.
Additionally, if there are many branches which grow straight up from the primary branch, most of those can be removed as well.
Once this branch is thinned out, continue your way up the tree, repeating the process on each primary branch.
Maintaining your juniper bonsai is a fun way to get to know your bonsai and understand how it grows. By removing foliage to open your tree up to the sun and air, you’ll be helping to keep it healthy. But remember, there is a right and wrong way to cut juniper foliage. Be sure to leave plenty of bright green growing tips so that your tree remains strong and beautiful, and never hedge prune it.