Hello. In this case, if the buds are still viable, so you can take into consideration applying a copper-containing solution to the wound (break), using a brush (e.g. – one sachet of Bordeaux mixture is dissolved in a small amount of water (0.5 liters) to form a paste). Copper has a bactericidal, fungicidal effect and helps wounds heal quickly. Later, if the plant can withstand its own weight, to stimulate rapid wound healing, you can consider using products that are specially formulated for this purpose, such as . If you think it is necessary, you can also bandage the broken area with materials suitable for this purpose (e.g. ).
Additionally, for improving the quality of the soil, stimulating the expansion of the roots and supporting a vigorous growth, it is recommended to regularly apply a fertilizer such as , by watering at the roots, according to the instructions in the product description.
The future development of the plant cannot be accurately predicted. If the magnolia does not start growing in spring, it is recommended to remove it and plant a healthy seedling, preferably in autumn, under optimal conditions for this operation (Ornamental trees and shrubs - Planting guide).