Basically, birch trees do pretty well on their own: the pioneer plants are robust survivors and don't need pruning to feel good. It is often different with the garden owner: you may want to limit the size of the tree because otherwise it takes up too much space or light. Here you can find out in which season the tree pruning is most appropriate.
A birch is best pruned in late fall
Birch pruning at the right time
Anyone who decides to cut a birch tree in the garden or a bonsai plant on the balcony should not proceed haphazardly. The right time determines the success of your project, while a wrong moment can possibly weaken the tree. Preferably choose frost-free days in late autumn. In this phase, the leaves have already been shed and the flow of sap is no longer pushing at full speed into the outermost treetops.
In contrast, it is not advisable to prune the birch when your spirits are in full swing in spring. Since the tree is pumping the water into the tips with all its strength during this time, it can drip intensively when cut. To avoid damage, cutting outside of the recommended season should only be done by experienced gardeners.