When should my bonsai be re-potted?
Early spring is the best time to re-pot your bonsai tree. March or April are good for most Bonsai trees.
During winter your Bonsai is dormant, and the tree will “rest” until Spring. Junipers, of course, are evergreens and don’t lose their leaves like deciduous tree types, but they do still go dormant. During the growing season, severe root pruning and transplanting can be stressful for your plant. Ultimately, pruning your bonsai trees roots should be done just before the growing season begins because that is when your cut root ends will begin to repair themselves.
Pruning your roots too early while they are dormant may lead to the roots not healing and being more susceptible to root rot and other diseases.
Why should I re-pot my bonsai?
A Bonsai tree lives in a very small world. Its entire world is which is bound by the dimensions of a small bonsai pot can become root-bound pretty quickly. As a Bonsai tree grows, the root system takes the place of what used to be soil. (That’s right, it “used” it).
A bonsai cannot thrive if it doesn’t have a proportionate amount of soil. As new roots are produced, older roots become ineffective and should be pruned off. Bonsai soil is the course by design to increase drainage. Replacing the soil is a quick way to fix a bonsai plant’s balance of pH and built up salts and chemicals.
Pruning and combing the roots of a Bonsai doesn’t mean cutting off the roots. The purpose is to prune out the ineffective old ones and the new ones if they’ve become too long.
A root system moves water and nutrients up to the top of the tree through a process called transpiration. Kind of like photosynthesis in reverse. Nearly all of the water that is absorbed by a root system is taken in through the tiny root hairs at the tips of the roots.
The larger roots are generally useless and can be cut away. A Bonsai tree has to be balanced between the roots that support the tree and photosynthesis. Small amounts of foliage, like a lot of bonsai trees, are designed to have, which means less photosynthesis that can support the roots. Therefore, you need fewer roots and vice versa.
What kind of soil do I need to use?
Use a potting medium specifically blended for bonsai. They are well worth the money. They are balanced and mixed to make sure that your bonsai is well-drained. Get one that has been “double sifted” which means the big chunks of stuff have been sifted out and the very small particles too. The dust from peat moss for example can choke out tender new root growth.