Detailed Guide to Propagating Osmanthus by Softwood Cuttings
Osmanthus (Osmanthus fragrans) is an evergreen tree of the family Oleaceae, with dense green foliage and a graceful form; when it blooms, its fragrance is rich and carries for miles. It is not only enjoyed for its flowers but can also be eaten and used to extract essential oil, giving it high ornamental and economic value. Because osmanthus produces few seeds and they are difficult to obtain, it is mostly propagated by cuttings; among these methods, softwood cutting propagation is easy to source material for...
Osmanthus (Osmanthus fragrans) is an evergreen tree of the family Oleaceae, with dense green foliage and a graceful form; when it blooms, its fragrance is rich and carries for miles. It is not only enjoyed for its flowers but can also be eaten and used to extract essential oil, giving it high ornamental and economic value. Because osmanthus produces few seeds and they are difficult to obtain, it is mostly propagated by cuttings; among these methods, softwood cutting propagation is easy to source material for, simple to perform, and gives a high survival rate. The key technical points are introduced below:
1. Cutting time. It is best carried out in two periods: from mid-May to mid-July and from mid-September to mid-October. At these times the new shoots have stopped growing, the branches contain more nutrients, their meristematic tissue has a stronger capacity for cell division, and the temperature is suitable, so the cuttings root and survive easily after planting.
2. Cutting bed preparation. It is best to choose light loamy farmland, plow it deeply, and make a bed. The bed should be 120 cm wide and 25 cm high, with ditches 40 cm wide; the soil must be finely broken up, the bed surface flat, and the ditches unobstructed. Above the cutting bed, build a plastic-film arch tunnel 50 cm above the bed surface, and above that build a shade shed 1.8 m above the bed surface with a light transmittance of 30%.
3. Collection of cuttings. Choose vigorous, pest- and disease-free superior plants as mother trees for cutting collection. Cut the current-year, semi-lignified softwood shoots from the upper outer part of the plant as cuttings. The collected shoots should be graded and tied into small bundles, with the bases wrapped in moist toilet paper and brought indoors for processing.
4. Cutting treatment. Cut the cuttings to 8-10 cm long, keeping 2 leaves on the upper part with half of each leaf cut off. Cut the top end flat and the base into a slanted cut, tie them into small bundles, then soak the basal 3 cm in a solution of 5 parts per 100,000 naphthaleneacetic acid (NAA) or 1 part per 10,000 No. 1 ABT rooting powder; after 1 hour, remove them and they are ready for planting.
5. Cutting operation. Cuttings should be planted in separate beds (sections) according to diameter class. At a spacing of 5 x 10 cm, first make holes in the cutting bed with a wooden peg of the same thickness as the cuttings, then insert 2/3 of each cutting into the hole and press the soil firmly around the cutting. Finally, water the cutting bed thoroughly with a 1:10,000 carbendazim solution to disinfect the soil and supply water to maintain moisture.
6. Management after cutting
Watering and shading. When there are no water droplets inside the tunnel film and the bed is dry, spray water to maintain moisture. The high-level shade shed should be covered early and uncovered late; the relative humidity inside the film tunnel should be kept above 85%, and the air temperature controlled between 18°C and 28°C. If the temperature is too high and the humidity too low, this can be adjusted by removing the covers and increasing spraying. If the temperature is too low and the humidity too high, this can be controlled by sealing the tunnel film and reducing spraying.
Spraying and loosening the soil. Along with watering, spray a 1:2,000 carbendazim solution once every 7 days to prevent the cuttings from being infected by pathogens and causing bark rot. Frequently carry out shallow inter-row cultivation of the cutting medium to maintain the permeability of the bed soil and prevent the young roots of the cuttings from rotting due to lack of oxygen.
Bud removal and fertilization. The sprouts at the base of the cuttings must be removed promptly to reduce nutrient consumption. Along with watering, spray a 0.2% urea or potassium dihydrogen phosphate solution once every 10 days to promote root and new shoot growth of the cuttings.
Removing the shed and transplanting. For summer-planted cuttings, the shade shed can be removed in October, and the young plants can be transplanted to an open-field nursery the following spring. For autumn-planted cuttings, the shade shed can be removed the following spring, and they can be transplanted to an open-field nursery in early summer. Both summer- and autumn-planted cuttings can remain in the bed for one year; in the winter of the following year, when the plants are 30-50 cm tall, they can be lifted from the nursery and planted in their permanent position.
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