The best time to plant osmanthus trees

The sweet-scented osmanthus tree prefers warm climatic conditions. The average temperature in the suitable growing areas ranges from 14 to 28°C, and the optimal growth temperature is 15 to 28°C. In the areas of China south of the Qinling Mountains and the Huai River, it can safely spend the winter outdoors. Although the osmanthus tree is not very cold-resistant, it still has better cold resistance than other evergreen broad-leaved tree species. Let’s learn about the best time to cultivate osmanthus trees.

1. Planting

Osmanthus fruits mature in April and May and can be harvested when the color of the skin changes from green to purple-black. The seeds need to go through a ripening period and usually need to be stored in sand for about half a year. After harvesting, water should be sprinkled on the pile to ferment, the pulp should be removed, the seeds should be allowed to dry naturally in a cool place, and then mixed with sand for storage.

The seeds stored in sand can be sown in autumn or spring. Before sowing, you need to prepare the land and apply enough base fertilizer. You can also sow in an indoor seedbed. When sowing, be sure to place the hilum on its side to avoid bending of the radicle and young stem, which would affect the growth of the seedling.

2. Grafting

The commonly used rootstocks for osmanthus grafting include Ligustrum lucidum, Ligustrum microphylla, etc. Before budding in spring, cut the rootstock and take 1 to 2 year old sturdy branches of osmanthus, 10 to 12 cm long, and make sure the cut surface is flat. Make a longitudinal cut about 2 to 3 cm deep on one side of the rootstock, insert the scion into the incision, make sure the cambium layers are aligned, tie it tightly with a plastic bag, and bury it in the soil for cultivation.

3. Cuttings

Before budding in spring, select healthy one-year-old branches, cut them into 5 to 10 cm long, keep 2 to 3 green leaves on the top, and cut off the lower leaves. Insert into river sand or loess seedbed, keep the row spacing at 3×20 cm, water or spray water in time after cutting, and shade, maintain the temperature at 20 to 25℃, and the relative humidity at 85 to 90%. It can be transplanted after rooting for about 2 months.

4. Layering

There are two methods for osmanthus layering: low pressure and high pressure. The low-pressure method is to select 1 to 2-year-old branches of low-stem mother trees from spring to early summer, cut or ring-bark them, and then press them into the soil to fix them. The high-pressure method is to select 1 to 2 year old sturdy branches from the mother tree in spring, girdling them, smear the wound with culture medium, tie them tightly with plastic bags from top to bottom, and cut them off from the mother plant for maintenance after roots grow in autumn.

5. Key points for planting potted osmanthus trees

Choosing a pot: It is best to use a deep round or square pot for osmanthus. The diameter of the pot mouth should be comparable to the diameter of the osmanthus branches and leaves, so as to facilitate the development of the root system. Purple clay pots or glazed pottery pots are best. The purple or ochre pot body forms a sharp contrast with the color of the flowers and leaves, enhancing the ornamental effect.

Soil: Osmanthus likes fertilizer, so fertile, loose, well-drained sandy loam should be used. The culture soil is usually prepared by mixing garden soil, compost and river sand in a ratio of 1:1:1 and then disinfected.

Cultivation: Osmanthus fragrans is suitable for planting in early spring or autumn. Before potting, place river sand or vermiculite at the bottom of the pot to facilitate ventilation and drainage, then cover it with peat soil or fine mud, filling the soil to near the edge of the pot. The soil surface should be 2 to 3 cm lower than the edge of the pot. After planting, water it thoroughly and move it to a shaded place for about 10 days to allow it to adapt to the new environment.

Watering: Follow the principle of "don't water unless the soil is dry, and water thoroughly when you do." Water every 3 to 4 days in spring and autumn, every day in summer, and every 7 to 10 days in winter. Make sure the water temperature is close to the soil temperature to avoid sudden cold or hot weather.

Fertilization: Osmanthus bonsai requires sufficient fertilizer . Apply nitrogen fertilizer when the shoots are growing, and apply phosphorus fertilizer when the flower buds are differentiating and before flowering. Let the soil in the pot dry slightly before fertilizing, and water it once the next day after fertilizing. When using fertilizers, the concentration should not be too high.

Pruning: Perform shaping and pruning in autumn, cut off overly strong branches, thin out overly dense branches, remove diseased and weak branches, concentrate nutrients, and promote flowering.

Repotting: Repot and change the soil every 2 to 3 years. The new pot should be larger. Cut off the old and dead roots, replace the soil with new one, and place decomposed cake fertilizer at the bottom of the pot as base fertilizer.

Disease prevention and control: Common diseases of osmanthus include leaf spot, sooty mold, etc. Appropriate prevention and control measures should be taken according to the disease situation.

Pest control: Common pests of osmanthus include sawflies, whiteflies, etc., which can be sprayed with pesticides of appropriate concentrations.

The above is an introduction to some cultivation points of osmanthus trees. You can formulate appropriate planting plans and maintenance management points based on the specific situation of the osmanthus trees and local climatic conditions.