How to Grow the Latest Wintersweet? A Detailed Guide to Cultivation Methods
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 well?
Propagation Methods
Wintersweet is commonly propagated by seed, grafting, cuttings, division and other methods.
1. Seed propagation: raise seedlings and then transplant. Harvest the fruit in June-July, remove 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 transplant after 2 years of cultivation.
2. Grafting propagation: use seedlings or division-propagated plants as rootstock, with cut grafting and approach grafting being best. In mid-March to April, select thick and relatively long branches, remove the terminal shoot, and cut them into 6-7cm long scions with 1-2 pairs of buds. For the rootstock, cut the seedling off 3-6cm above the ground, perform cut grafting, apply mud slurry, and seal the rootstock and scion together. After 3 years of cultivation, it becomes a plant.
3. Cutting propagation: softwood cuttings in summer are preferable. After dipping the cuttings in 1×10-4α-naphthaleneacetic acid for 1min, insert them in a shaded plastic film tunnel, where they root relatively easily.
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 1.3m each, and plant 1 seedling per hole. Each year in early spring and autumn, carry out one intertillage and weeding plus one topdressing, mainly with human and livestock manure water. To promote flowering, every year in March-April, shorten the branches and pinch out the growing tips.
Cultivation Methods
1. Plowing: plow after flowering, to a depth of 20-25cm, slightly shallower under the canopy to avoid damaging the roots.
2. Fertilizing: in spring after flowering, apply base fertilizer together 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, 20-30cm deep. For mature trees, apply 3000-5000kg of high-quality decomposed farmyard manure per mu; for 1-2 year old young trees, the fertilizer amount is 1/3-1/2 that of mature trees. Apply one topdressing at flower bud differentiation in late June. Apply 20kg of compound fertilizer per mu as topdressing, broadcast below the outer edge of the canopy.
3. Watering: wintersweet is drought-tolerant, but water should also be supplemented in dry seasons. In July, during the flower bud differentiation period, 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 keep 3-4 robust branches evenly distributed in all directions as the main trunks (if there are no branches, leave 4-5 plump buds on the ground and prune heavily), cut back to leave 3-5 nodes, and after sprouting use them as trunk extension shoots and side branches. Take care that the main branches do not overlap or cross each other, and promptly remove root suckers, sprouting shoots, weak branches and dead branches from the lower part.
② Bud removal: when wintersweet leaf buds have sprouted about 50cm, remove the excess tender buds that are dense, inward-facing and close to the ground, to reduce nutrient consumption. In the rainy season, promptly cut away the miscellaneous branches, useless branches, branches that disrupt 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-damaged 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; do not cover or bump randomly, so as not to knock off the flower buds.
④ Supplementary pruning after flowering: after wintersweet flowers fade, supplementary pruning should be done promptly. The main task is to thin out aged branches, dead branches, overly dense branches and leggy branches, and to cut back declining main branches or branch groups, so as to rejuvenate the branch vigor and tree vigor. However, for main branches that are too high, too long or too strong, cut back to a relatively large, moderate, slanting branch, letting a weak branch take the lead, to control branch height, branch length and branch vigor, and achieve balanced branch vigor and tree vigor. Shorten one-year-old branches: cut the main branch extension shoots back to leave 30-40cm, leave 10-20cm on other relatively strong branches, and leave 1 pair of buds on weak branches or thin them out. After weak branches are thinned out, new shoots can still grow from the base. In addition, after the flowers fade, promptly pinch off the faded flowers (when seeds are not wanted), to prevent fruiting from consuming nutrients, so that next year the branches will be thick and the flowers abundant.
Pest and Disease Control
Wintersweet has relatively few pests and diseases. Occasionally trunk-boring pests occur; during dormant pruning, cut off the affected branches together with the pests and burn them.
Harvesting
Wintersweet fresh cut flowers are generally harvested when the flower buds first open, and placed in a cool place after harvesting. After harvesting, they can be kept fresh for 30-50d under refrigeration at 0-2℃. When cutting branches, the lower cut should be slanted at 45°, the upper cut level, and the cuts smooth.