Planting and Caring for Magnolia
Magnolia grows comparatively well even after being transplanted.
When the tree is being transplanted the rootlets may be damaged because of the long, principal roots. Therefore, it is a good idea to cut, in the spring of the previous year, the long roots of a tree which is to be transplanted so that it will be able to strike many rootlets before being transplanted.
The tree must be transplanted into fairly fertile soil with a moderate amount of moisture and a lot of humus and in places that are not exposed to strong light for long. After the tree has been transplanted its branches should be thinned out, depending on the condition of the roots. In the case of a magnolia which used to grow in the mountains, it is a good idea to cut the tree’s crown and improve it after it has been transplanted.
A magnolia should be shaped and pruned well. In order to grow magnolia to look like a cluster, the central leader must be cut, leaving some 15-20 centimetres so that it grows 3 or 4 principal branches; the following year these principal branches must again be cut to a height of 20-30 centimetres so that 2 or 3 secondary branches are produced for each principal branch.
Magnolia has few twigs because it is not able to produce many buds. Therefore, only dry or decaying branches and other unnecessary branches should be cut. Old or weak trees bear few flowers and are ugly; therefore, they should be improved. If one wants to grow a magnolia in a pot, all that is needed is bud grafting, root grafting or shoot grafting on 2- or 3-year old trees prior to transplanting them into nursery beds and growing them there for a year before potting them. In natural conditions the physiological dormancy of magnolia finishes towards the end of December; in about 40 days after it issues its buds again the tree begins to bloom. Therefore, if one wants to control the period of flowering, it should be done in conformity with this. That is to say, the tree should be put to dormancy in natural conditions and then 14 placed in a greenhouse some 50 to 60 days before it is due to bloom.
Based on: FLPH - Magnolia Sieboldii, Korea's National Flower