How to Grow Japanese Honeysuckle in Cold Regions? A Full Analysis of Cultivation Experience
Japanese honeysuckle (Lonicera japonica) is a semi-evergreen climbing shrub. Its flowers are white when they first open and turn yellow after exposure to sunlight, hence its Chinese medicine name "Shuanghua" (double flower); it clears heat and detoxifies. Its vine is known in Chinese medicine as "Jinyinteng" (honeysuckle stem); besides having the effects of the double flower, it also clears heat from the meridians and stops pain in the meridians. Its flowers are fragrant with a sweet note and are a good material for scenting flower tea; using its leaves and flowers to make a tea drink can relieve summer heat and improve eyesight. In the south it is planted on a large scale as a medicinal plant, or widely cultivated in courtyards as vertical greening to scent and beautify the environment. Previously in the north it could only be grown in boxes or as bonsai, and had to overwinter indoors or in a cellar. According to the author's trial planting, it can also be grown in the open ground in cold regions. The key management points are as follows:
1. Planting: Japanese honeysuckle likes sun and also tolerates shade, and is not choosy about soil. With a plant spacing of 60 cm and a hole depth of 40-50 cm, mix farmyard manure with the soil from the hole, spread the roots out and plant, then water thoroughly.
2. Trellising: When the plant is 30 cm tall, set a pole 10 cm from the root and tie the plant to it; afterward, as the branches spread and grow deeper, guide and fix the vines upward. This prevents the branches from drooping and tangling chaotically and affecting growth. In the same year it can grow to 3-4 m, so the pole should be tall and the fixing should be firm, and wire or thin wooden sticks should be stretched horizontally on the pole so that the planted vines can be evenly fixed, which helps ventilation and light.
3. Pruning: When new shoots are 30 cm tall, pinch out the growing tips to encourage side branches; when side branches are 50 cm tall, pinch them again to encourage third-order branches. After late June, apart from topping overly vigorous shoots and thinning out diseased and weak branches, do not prune further, to ensure flower yield. Afterward, the vines and branches must be cut back every year to prevent the lower part from becoming bare; take care to control long overly vigorous shoots and cut out overly dense, overly old, and diseased and weak branches.
4. Fertilizing: Japanese honeysuckle grows rapidly and has a large amount of branches and leaves. Its flowers bloom from mid-June until the first freeze, consuming a lot of nutrients, so in autumn and early spring apply compost and stable manure around the roots, and after bud break and during flower picking frequently apply diluted liquid fertilizer.
5. Harvesting: Japanese honeysuckle has a long harvest period, and its flower clusters are numerous and long, up to 15 cm at most, but the whole cluster cannot be picked; instead, before 9 a.m. on a sunny day, gently pick the buds whose upper part has already swollen, turned white, and is about to open. Place them on a mat or in a basket, spread about 1 cm thick, in eight or nine layers. Do not turn them before they are dry, and even more do not touch them with your hands, otherwise they will turn black. If they cannot be dried in the sun on the same day or if it rains, move them indoors, but they must not be stored in a pile; sun them again on a sunny day or the next day.
6. Propagation: In spring, select vigorous 1-2 year old branches, take two nodes as one section, cut the lower end diagonally 1 cm below the node, and cut the upper end flat 1.5 cm above the node; all cuts must be smooth. Poke holes in the prepared bed soil with a wooden stick, insert the cuttings, water thoroughly, and cover with a plastic tunnel. In summer, you can also take vigorous one-year-old branches that have become semi-lignified and insert them in the same way as above, but provide moderate shade.
7. Wintering and cold protection: Japanese honeysuckle will not die from freezing. After taking it down in late autumn, if there are few vines, coil them up; if there are many, lay the vines flat on the ground, water thoroughly, and cover with about 15 cm of sawdust or other mulch, and it will overwinter safely. The next year on “May 1” remove the cold protection, put up a small plastic tunnel, and gradually uncover the film to harden them in non-scorching sunlight, windless conditions, or at night; after more than ten days, remove the tunnel and let them grow naturally.