I recently received this question from a reader who would like to transplant their Bonsai. Read below to get some tips when transplanting your Bonsai.
Question: Can you take a dormant bonsai tree from a 6" deep pot and cut down roots to put it in a traditional shallow pot?
The short answer is no.
I would not recommend cutting back roots on your Bonsai when it is in dormancy. The best time to repot and cut back roots is in the Spring after new buds have sprouted.
During the winter or dormant season, your Bonsai is storing energy resources in the roots. As temperatures rise the roots of a Bonsai begin to become active. The energy stored in the roots will then slowly begin to move back up to the tree.
If you cut back the roots of a Bonsai when it is dormant you will remove the stored energy which the tree will need when it's time to come out of dormancy in the spring.
Once your Bonsai has sprouted new buds in the spring time, it will be a sign most of the energy has moved from the roots up to the branches of the tree.
This will be the best time to repot your Bonsai.
There are also a number of other factors to consider with regards to your question, the first of which is what type of tree are you repotting?
If your tree is a forgiving or hearty species such as a Ficus or Maples, it will be more forgiving to drastic root reduction. If your tree is more delicate such as a Black Pine will want to reduced the root ball in stages over a number of years.
In addition, some trees simply do better in deep pots. Bougainvillea are very hearty Bonsai, however they simply do much better in deeper pots.
Never cut back or repot your Bonsai when it is dormant.
After your Bonsai has sprouted new buds in the spring is the best time to cut back roots.
If you're working with a delicate species of Bonsai, you will want to cut back your root ball in stages over a number of years. This will make give your Bonsai more time to adapt to the smaller root ball.
Do research beforehand to see if the roots of your species of Bonsai will do better in deeper pots. Some species simply do better in deep pots.
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