How to grow potted Dan Gui (Osmanthus fragrans 'Dangui')? A detailed guide to cultivation methods
Dan Gui is a type of osmanthus tree, an evergreen tree of the genus Osmanthus in the family Oleaceae, native to southwestern China. Through long-term artificial cultivation, natural hybridization and artificial selection, a rich and diverse range of cultivars has formed. It is now widely cultivated in various regions and commonly used as a landscape tree species. Let's take a look together at the cultivation methods for potted Dan Gui!
Reasonable watering
For potted Dan Gui, the soil should follow the principle of not watering until dry, and watering thoroughly when you do. However, spray the leaves with clean water once a day, evenly moistening all branches and leaves, until water droplets begin to drip down, to keep the leaves moist and wash away dust clinging to the leaves. After Qingming Festival, move the Dan Gui outdoors and give it one thorough watering. In summer, water in the morning and evening; in winter, water around noon, so that the water temperature is close to the soil temperature and does not cause sudden cold or heat. Be careful not to let water accumulate. In winter, simply keep the potting soil moist.
Timely fertilization
When Dan Gui sprouts new shoots, apply nitrogen fertilizer 1 to 2 times to promote branch and leaf growth; before flower bud differentiation and flowering, mainly apply phosphorus fertilizer. After moving the Dan Gui outdoors in spring, begin watering with diluted decomposed soybean cake, sesame paste, fish waste water, etc., once every half month, then once a week from the end of May until before flowering, gradually increasing the fertilizer concentration. From July to August, apply a 0.5% potassium dihydrogen phosphate solution as a top dressing once every half month. After flowering, apply a light fertilizer solution once to avoid triggering autumn shoots. In winter, apply more organic fertilizer and phosphorus-potassium fertilizer. Before fertilizing, the potting soil should be slightly dry, and it is best to loosen the soil first to facilitate fertilizer absorption; water once the next day.
Choosing and repotting pots
For Dan Gui, flower pots made of purple clay ceramic or glazed ceramic are best, and colors such as purple or ochre are preferable, as they create a sharp contrast with the colors of the flowers and leaves and enhance the ornamental effect. Potted Dan Gui should be repotted and have its soil changed once every 2 to 3 years; trim away some old roots and dead roots, and use a bamboo stick to remove part of the old soil. The soil mix ratio for potted Dan Gui is not very strict; generally, garden soil, composted manure and river sand can be mixed in equal thirds. After planting in spring, water thoroughly, then move to a shaded place for about 10 days to let it "adapt to the pot." Do not fertilize during this adaptation period; only after it resumes growth and grows new leaves may you water and fertilize.
Shaping and pruning
For Dan Gui, the best shapes are curved-trunk, slanting-trunk or flowing styles. Shaping generally uses a combination of wiring and pruning; the main trunk can be wired into a curved or slanting form. This is best done in autumn. For plants that grow very tall with very bare lower branches and a poor tree shape, cut off all the top branches at 2/3 or 3/4 of the height. For plants that are "top-heavy," cut away the overly dense upper branches and keep only the smaller lower branches. For plants with overly dense branches, thin them out. After flowering, do another round of pruning, cutting off leggy branches, dead branches, diseased and pest-infested branches, and dense weak branches.
Overwintering management
The room temperature should be kept at O to 5°C, and relative humidity at 50 to 80%. In winter, a cold room should have good light; especially before the buds begin to sprout in early spring, plenty of sunlight is required. The following spring, in North China, move potted Dan Gui outdoors after Grain Rain (around Awakening of Insects in the Yellow River-Huai River basin). After moving outdoors, first place them together in a wind-sheltered, sunny spot, then later spread them out in rows so they gradually adapt to the outdoor environment.
Pest and disease control
Common diseases of Dan Gui include leaf spot, sooty mold, algal leaf spot, root rot, and iron deficiency, and control should be targeted to the disease condition. Leaf spot, sooty mold and algal leaf spot can be controlled by spraying 0.5 Bordeaux mixture or 5% carbendazim 500 to 1000 times solution. For root rot, keep the soil loose and breathable and avoid water accumulation; if root rot is caused by fungi, irrigate the roots with 200 to 300 times solution of amobam. Common pests of Dan Gui include sawflies, whiteflies, mites, long white scale insects, and yellow-spotted moths. Sawflies, whiteflies and mites can be killed by spraying 40% dimethoate 1500 to 3000 times solution. For long white scale insects, besides manual brushing off, during the first and second instar nymph stages, spray 40% omethoate 1000 times solution or 40% fenitrothion 500 times solution.