How to care for and manage potted white magnolia (Michelia alba) in winter so it survives the cold safely

White magnolia (Michelia alba) is a famous fragrant flowering tree species, often used in South China as a shade tree and street tree; its fragrant flowers can be used to scent flower tea.

Winter management

White magnolia is not tolerant of low temperatures, so it must be moved into a greenhouse before the first frost. The indoor temperature should be kept at 10-12°C, watered once every 7-10 days, and no fertilizer should be applied. Before taking it out of the greenhouse (before the buds sprout), control watering, even to the point of making the soil extremely dry, to encourage the growth of new shoots. Special attention should be paid to not watering excessively, otherwise the leaves will turn red or even drop, leading to the death of the whole plant.

Key points for routine care of white magnolia

White magnolia is mostly propagated by the approach grafting method.

The rootstock can be purple magnolia (also known as Mubí or Xinyí) or champaca (Michelia champaca). Purple magnolia is propagated by layering or division. Champaca is propagated by seed. Purple magnolia has strong cold resistance, so white magnolia cultivated in the north mostly uses purple magnolia as the rootstock. The best time for approach grafting is from late June to early to mid-July.

For the scion, use branches from the previous year. After grafting, bind with plastic film strips and seal with mud. After 40 days it will have healed and can be separated from the mother tree to form a separate plant.

White magnolia is rather delicate and difficult to manage. It likes light and does not tolerate shade; it likes a warm, humid, well-ventilated environment and requires well-drained, slightly acidic sandy loam. It fears cold, so in the north it must overwinter in a greenhouse, and the temperature must not be lower than 12°C. In the greenhouse, water must not be excessive; do not water until it is dry, and when dry, water thoroughly. If the leaves turn red, it means the roots are suffering from too much water. If the leaves wrinkle in winter, it indicates frost damage. In winter, the water used for white magnolia must not be too cold; it is best to use water stored in the greenhouse, and water with plain water only, with no need for fertilizer. After Grain Rain, white magnolia should be moved out of the greenhouse; the bottom of the pot must not sit directly on the ground and should be propped up on something to allow air circulation. In places where air humidity is particularly low, shade must be provided at midday during the hot summer, otherwise the flowers and leaves are at risk of being scorched by the sun.

White magnolia likes rich fertilizer during the peak growing season. Apply fertilizer once every 2-3 days. At this time, watering or fertilizing should be done in the morning and evening, avoiding the high midday heat.

Every 1-2 years, repot white magnolia once in spring when it is taken out of the greenhouse. When repotting, apart from removing a very small amount of old, decayed roots, generally do not prune off other fibrous roots.