How to grow Magnolia denudata? A detailed guide to the latest cultivation methods

Magnolia denudata, also known as magnolia, spring-welcoming flower and magnolia flower, is the white-flowered variety among magnolias. It is a deciduous tree of the genus Magnolia in the family Magnoliaceae, native to central China, and is now cultivated in Beijing and south of the Yellow River basin. The flowers are white, large and fragrant, opening before the leaves, with a flowering period of about 10 days. It has high ornamental value. Let us take a look below at how to grow Magnolia denudata!

Growth habits of Magnolia denudata

Magnolia denudata is native to Java, Indonesia, and is now widely planted in Southeast Asia. Cultivation is especially flourishing in Fujian, Guangdong, Guangxi, Yunnan and other provinces and regions of China, and it still grows wild in places such as Lushan, Huangshan, Emeishan and Jushishan. It is suitable for growing in a warm, humid climate and in fertile, loose soil. It likes light, is not tolerant of drought, and is not tolerant of waterlogging either; if the roots are submerged for 2-3 days, they die. It is relatively sensitive to toxic gases such as sulfur dioxide and chlorine, and has poor resistance.

Propagation methods of Magnolia denudata

1. Seed propagation

① Seed collection: usually in early to mid-September, when the fruit turns red and some split open to reveal red seeds, they can be harvested. After threshing, select plump, brightly colored seeds as seed.

② Seed treatment: soak the seeds in warm water at 50-60°C for 10 minutes, mix with fine sand and rub to remove the waxy layer, screen out the seeds, and store them in stratification with 3 times their volume of moist sand in a wind-sheltered, sun-facing pit, covered with grass to keep warm and moist. When about 50% of the seeds split open and show white in the following spring, take them out and sow. For autumn sowing, they can be sown as soon as collected. At this time, the fresh seeds should be soaked in warm water with plant ash added for 3-5 days, rubbed to remove [the waxy layer], watered frequently, and sown after the seeds split.

③ Seed sowing: the seedbed should be made into a high ridge 1.2 m wide and 30 cm high, with a path 30 cm wide. On the ridge, open furrows crosswise at a row spacing of 20 cm for drilling, with a sowing width of 5 cm and a furrow depth of 6 cm. After sowing, cover with 3 cm of soil and then with rice straw. Sow in early March, and full seedlings can be achieved in mid-to-late May. Autumn-sown seeds emerge in about a little over 1 month. After emergence, promptly remove the covering, insert branches for shade, and water frequently to maintain a moist environment. Strengthen management, remove weeds and apply topdressing, and after two years of cultivation they can be planted out.

2. Division propagation: in late winter and early spring, dig up old plants with tillers, keeping the roots, and plant them as they are dug.

3. Layering: in early spring, gently press the small branches of the mother tree near the ground into the soil without breaking them, cover firmly with soil and secure with crossed stakes, so that the branches grow young roots and new shoots at the ground. After one year they can be planted out.

4. Air layering: in late June, select young branches on the mother plant, cut away the bark at the branching point with a knife, pare it into a semicircular shape, wrap it with plastic film or a bamboo tube, fill it with moist fertile soil, and tie it tightly with rope outside so it does not move, keeping it moist. In late April of the following year, check that new roots have formed, then remove it and plant it out.

5. Cutting propagation: in summer and autumn, select 1-2 year old young shoots, cut them into 15-20 cm long cuttings, flatten the upper end, cut the lower end into a horseshoe shape, moisten them, then dip them in a powder composed of 500 ppm indolebutyric acid plus talc powder, and insert them obliquely into the seedbed, leaving 2 nodes at the lower end and exposing one node above the ground. Build a shade frame, keep the soil moist, and roots will form in about 1 month.

6. Grafting propagation: seedlings grown from seed need 7-8 years of cultivation before they bloom, while planted grafted seedlings need only 2-3 years to bloom. Commonly used grafting methods include “bud grafting” and “cut grafting”, both the same as for general flowering trees and shrubs.

Cultivation methods for Magnolia denudata

1. Transplant preparation: carry out deep plowing and soil preparation in autumn and winter, and make beds 1-1.5 m wide the following spring. During soil preparation, apply fertilizer and remove weeds to ensure vigorous growth of the seedlings after transplanting.

2. Transplant timing: the suitable time for transplanting is when the seedlings have grown 2-3 true leaves after emergence. 1-2 days before lifting the seedlings, if the weather is dry and the soil is compacted, water the seedlings to be transplanted thoroughly, once a day. When lifting the seedlings, so as not to damage the root system, if the soil is rather compacted, use a small shovel (2-3 cm wide) inserted into the soil at a 45° angle to help loosen the soil. Then lift the seedlings upward until the root system is completely lifted out of the soil surface.

3. Timely planting: the planting hole can be dug temporarily with a small shovel at the time of transplanting. Place the seedling upright, bury the root crown 1-2 cm into the soil, press the soil firm with your hands, and then water.

4. Light and temperature: it is suitable for growing in an environment with ample sunlight. Sufficient light can make the plant lush with branches and leaves, with more flowers and a stronger fragrance. It can endure short periods of low temperature down to -20°C. In the Zhengzhou area it can overwinter in the open field, and in the Beijing area it can generally also overwinter in the open field, but when the temperature is below -20°C, cold protection measures are needed. It is relatively sensitive to temperature, and high temperatures can make the flowering time earlier.

5. Watering and fertilizing: fertilizer can be applied 2 times a year, one is the wintering fertilizer, and the other is the post-bloom fertilizer. Thin, well-rotted human manure and urine are preferable; concentrated fertilizer should be avoided. Watering can be done as appropriate: water less on cloudy days and more in dry times. In spring, growth is vigorous and water demand is somewhat greater, so water thoroughly 2 times a month; in summer, a little more may be given. In autumn, reduce the amount of water; in winter, generally water lightly, but if the soil is too dry, water once.

6. Shaping and pruning: carry this out after the flowers fade and before the leaf buds sprout. Generally no pruning is done, because magnolia branches have poor callusing ability, so no major shaping or pruning is done. It is only necessary to cut out overly dense branches, water sprouts, crossing branches, dead branches and pest- or disease-damaged branches to cultivate a reasonable tree shape and make the form graceful. Directly applying a wound-healing and anti-decay membrane to cut and saw wounds can quickly form a tough soft film closely attached to the wood, protecting the growth of wound healing tissue, preventing infection by rot-causing pathogens, preventing soil and rainwater contamination, and preventing freezing and wound cracking.

7. Flowering control: if you want magnolia to bloom at New Year's Day or the Spring Festival, move potted magnolia 40-50 days in advance into a low-temperature greenhouse to gradually break dormancy, then after 25-30 days place it in a high-temperature greenhouse, maintain air humidity above 60%, and spray flower-strengthening agent. It will then bloom at the desired time, which can promote strong flower buds, plump petals, vivid flower color, rich fragrance and a longer flowering period. How to make potted Magnolia denudata have large flowers, more blooms, fragrant flowers and vivid color, and also a long flowering period, the key is to strengthen the flowering-period management of potted Magnolia denudata.

8. Pest and disease control: the main insect pests of Magnolia denudata are aphids and scale insects. In the management process, in addition to paying attention to controlling yellowing disease and root rot, anthracnose should also be controlled. For scale insect damage, spray with 0.3% to 0.4% sour vinegar solution, or remove them by hand. Aphids damage tender buds and flower buds; they can be killed with sumithion, or sprayed with a 500-fold solution of washing powder, or a cotton swab dipped in washing powder solution can be used to wipe off the pests, after which the branches and leaves should be rinsed with clean water. If disease is found, promptly remove diseased plants and leaves, and at the same time spray the leaves with a 500-fold to 800-fold aqueous solution of 50% carbendazim, or use an 800-fold to 1000-fold solution of 70% thiophanate for control.