To keep a bonsai tree small, you must strategically and methodically restrict its nutrient intake and root growth. These actions yield results that defy the misconception that bonsai trees are, genetically, dwarf plants. In fact, when planted in the ground, they have the potential to reach over 100 feet. So, how do you stop that from happening?
Root Confinement
Naturally, a bonsai’s roots would grow and disperse deep into the ground in search of as much water and nutrients as the soil has to offer. The more it finds, the bigger it grows. This is why, to keep a bonsai tree small, it is deliberately planted in a shallow pot.
Planting a bonsai in a shallow pot minimises the volume of water and nutrients it can absorb at one time. Not starving it, but essentially placing it on a diet. Despite this, the roots will continue to grow. Therefore, it is essential to remove the tree from the pot and prune the roots every few years. This eliminates the thick anchor roots that provide the most nutrients, and allows feeder roots to grow. These smaller, finer roots keep the tree healthy, but do not absorb the volume of energy needed for drastic vertical growth.
Strategic Pruning
Trees have a biological trait that is extremely helpful for pruning, named apical dominance. This term refers to the tree’s ability to send most of its growth energy to its highest point. In nature, this function exists to help it outcompete other trees for sunlight due to vertical growth.
So, to prevent a bonsai from growing upwards, the new buds at the tips of the branches are consistently pinched or cut off. This process forces the tree to redirect its energy to the lower branches, resulting in smaller, delicate branches instead of a single thick one.
Learn more about correct pruning techniques in this article!
Controlled Stress
In certain species, to keep the leaves of a bonsai tree small, they are periodically defoliated. This process refers to the removal of most or all of the leaves of the tree in the summer. This is so that the timing of their regrowth falls in autumn and winter.
During autumn and winter, the bonsai receives less sunlight, and therefore, the new leaves are significantly smaller than those they have replaced. This happens because the number of cells in each leaf is reduced, effectively creating a proportionate miniature.
Thoughtful Wiring
Wiring a bonsai tree not only serves to shape it the way you like. Wiring that creates horizontal and downward-facing branches can actually help to keep a bonsai tree small. It essentially creates a speed bump, which disrupts and slows the vertical flow of sap and growth hormones. The absence of sap and hormones encourages the tree to grow shorter, denser back buds, closer to the trunk, rather than growing taller.
Read our article to discover more about wiring bonsai trees.
Need Advice About Keeping a Bonsai Tree Small?
Bonsai2U is a UK-leading specialist in bonsai trees. We supply a range of species at various levels of expertise, and offer advice and product packages for their ongoing care. So, please get in touch if you need advice on keeping your bonsai tree small. Our experts are happy to help.
