How to Grow Wintersweet (Chimonanthus praecox)? Detailed Growing Methods and Precautions
Wintersweet prefers a warm climate, is relatively cold-tolerant and drought-tolerant, and slightly shade-tolerant; it likes sunlight; it dislikes waterlogging. It is best planted in deep, loose, fertile and well-drained sandy loam; it grows poorly on heavy clay and alkaline soil. So how should wintersweet be grown properly?
Propagation Methods
Wintersweet is commonly propagated by seed, grafting, cuttings, division and other methods.
1. Seed propagation: use seedling raising and transplanting. Harvest the fruit in June-July, extract the seeds, and store them in moist sand for later use. Sow in March of the second year. Take out the seeds, rub off the waxy coating in water together with the sand, then sow. During the seedling stage, pay attention to weeding and fertilizing, and cultivate for 2 years before transplanting.
2. Grafting propagation: use seedlings or divided plants as rootstock; cut grafting and approach grafting are best. In mid-March to April, select thick and relatively long branches, remove the top shoot, and cut them into 6-7 cm long scions with 1-2 pairs of buds. For the rootstock, cut the seedling off 3-6 cm above the ground, perform cut grafting, apply mud slurry, and seal the rootstock and scion. After 3 years of cultivation, it becomes a plant.
3. Cutting propagation: summer softwood cuttings are best. Dip the cuttings in 1×10-4α-naphthaleneacetic acid for 1 min, then insert them in a shaded plastic film shed, where rooting is relatively easy.
4. Division propagation: in February-March, dig up the sucker shoots produced by the mother plant and plant them. For transplanting, open holes at a row spacing and plant spacing of about 1.3 m each, and plant 1 seedling per hole. Each year in early spring and autumn, carry out one intertillage and weeding and one topdressing, mainly with human and livestock manure water. To promote flowering, every year in March-April, cut the branches short and pinch off the growing tips.
Cultivation Methods
1. Plowing: plow after flowering, with a plowing depth of 20-25 cm, slightly shallower under the tree canopy to avoid damaging the roots.
2. Fertilizing: apply base fertilizer in spring after flowering in combination with plowing. Wintersweet likes fertilizer, but avoid applying concentrated fertilizer. Open ring-shaped or strip-shaped fertilizer trenches below the outer edge of the canopy, with a trench depth of 20-30 cm. For adult trees, apply 3000-5000 kg of high-quality decomposed farmyard manure per mu; for 1-2 year old young trees, the fertilization amount is 1/3-1/2 that of adult trees. Apply one topdressing at the time of flower bud differentiation in late June. Apply 20 kg of compound fertilizer per mu by broadcasting it below the outer edge of the canopy.
3. Watering: wintersweet is drought-tolerant, but water should also be supplemented in dry seasons. During the flower bud differentiation period in July, suitable soil moisture should be maintained. During the flowering period, the soil should remain moderately dry to reduce flower drop.
4. Shaping and pruning
① Shaping: the multi-stem form is commonly used. After planting, select and retain 3-4 robust branches distributed evenly around as the main stems (if there are no branches, leave 4-5 plump buds above the ground and prune heavily), cut and retain 3-5 nodes, and after sprouting use them as main stem extension shoots and side branches. Note that the main branches should not overlap or cross each other, and promptly remove the lower root suckers, sprouts, weak branches and dead branches.
② Bud removal: when wintersweet leaf buds have sprouted about 50 cm, remove the excess tender buds that are dense, inward-growing and close to the ground to reduce nutrient consumption. In the rainy season, promptly prune away the grown miscellaneous branches, useless branches, branches that disturb the tree shape, and branches that block wind and light.
③ Pre-flowering pruning: after wintersweet loses its leaves and before the flower buds swell, for some long branches, leave a pair of leaf buds above the flower buds and cut off the upper part without flower buds; cut off dead branches, diseased and pest-infested branches, overly weak branches, and dense, leggy non-flowering branches and root suckers not used for renewal, to save nutrients. When pruning before flowering, operate carefully and do not randomly cover or bump them, so as not to knock off the flower buds.
④ Supplementary pruning after flowering: after wintersweet flowers fade, supplementary pruning should be carried out in time. The main task is to thin out senescent branches, dead branches, overly dense branches and leggy branches, and retract weak main branches or branch groups, so as to rejuvenate branch vigor and tree vigor. However, for main branches that are too tall, too long or too strong, they can be retracted at a relatively large, moderately vigorous slanting branch, with a weak branch leading, to control branch height, branch length and branch vigor, and achieve the purpose of balancing branch vigor and tree vigor. Shorten one-year-old branches: cut the main branch extension shoots leaving 30-40 cm, leave 10-20 cm for other relatively strong branches, and leave 1 pair of buds or thin out weak branches. After weak branches are thinned out, new shoots can still grow from the base. In addition, after the flowers fade, promptly pinch off the residual flowers (when seeds are not wanted) to prevent fruiting from consuming nutrients, so that the branches will be thick and the flowers abundant the next year.
Pest and Disease Control
Wintersweet has relatively few pests and diseases. Occasionally, trunk-boring pests occur; combined with dormant-season pruning, the affected branches can be cut off together with the pests and burned.
Harvesting
Wintersweet fresh cut flowers are generally harvested when the flower buds first open, and after harvesting are placed in a cool place. After harvesting, they can be kept fresh for 30-50 d under refrigerated conditions at 0-2°C. When cutting branches, the lower cut of the branch should be slanted at 45°, and the upper cut should be flat and smooth.