Vigor and dominance
Pinching spring growth to redistribute a tree's energy reserves.
Every time I look out my window these days, I notice new growth on a tree. This is the season when dormant buds swell and shoot out new leaves and stems, which means it’s my job to pluck them out.
I had a hard time wrapping my head around this when I was first learning about bonsai training. How do you…uh…grow a tree if you’re pinching out new growth? I bought this boxwood shrub from an online shop as training material to get some hands-on experience. Emphasis on the training; my first attempt at styling this tree left it a mangled mess. There’s a reason I’m not showing you the whole thing.
If you’re going to train a bonsai, the experts say, you need to understand apical dominance. There are far better descriptions of this from people who actually know what they’re doing, but basically, a tree has a finite amount of energy, or vigor, in garden speak. Apical dominance is a tree’s tendency to concentrate that energy towards growing upwards and outwards. That is, the top of the tree and its outermost branches tend to develop the most buds which grow the fastest, while lower and interior branches yield fewer buds and grow more slowly.
Pinching new growth redistributes a tree’s finite energy from where it wants to grow to where you want it to grow. If you pinch out shoots from the tip of the branch, it’s forced to rely on secondary branches to fork out and continue growing. Ideally, you’ll also encourage the tree to develop new buds in apically…submissive areas. This is crucial to the miniature proportions of a bonsai.
In a state of nature, it makes sense for a tree to direct all its growth upwards and outwards. There are only so many square feet of sunlight and lots of competition from other trees vying for space. As the expanding canopy shades out less vigorous branches underneath, the lower limbs of the tree die off. Slower-growing trees that can’t keep up either adapt to lower light conditions or starve.
Good for the state of nature, not so good in a bonsai pot, where a tree is freed from those nasty, brutish conditions and where thick, vigorous lower branches that fork and twist from the trunk contribute to a specimen’s sense of age.
When I was working on my spruce last weekend, I removed as many as half of the buds from the top parts of the tree and barely touched the lower and inner branches. Now there are fewer overall buds for the tree to direct its energy towards, which are more evenly distributed through its structure. The lower and interior buds will still grow the slowest, but they’ll receive a greater share of vigor and be more likely to thrive. Call it arboreal socialism, spurred on by a culling of the tree’s fattest, most privileged population.
Did I mention spruce tips taste delicious?
Tree reading
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