How to Grow Osmanthus Well? A Complete Guide to Care Techniques

Osmanthus is one of China's ten traditional famous flowers, an excellent landscape tree that combines greening, beautification and fragrance, with both ornamental and practical value. Bonsai made from osmanthus stays evergreen in all four seasons, with abundant flowers and a fragrant scent, offering high ornamental value. With proper management it can grow luxuriant branches and leaves, bloom continuously, and produce abundant, fragrant flowers. Let's take a look below at how to grow osmanthus well!

How to Grow Osmanthus Well?

1. Timely watering: For potted osmanthus soil, follow the principle of not watering until dry, and watering thoroughly when you do, but spray the leaves with clean water once a day. After Qingming Festival, move the osmanthus outdoors and water it thoroughly once. 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.

2. Reasonable fertilizing: Osmanthus is grown mainly for its flowers, so it should be given sufficient fertilizer. When new shoots emerge, apply nitrogen fertilizer 1 to 2 times; before flower bud differentiation and flowering, mainly apply phosphorus fertilizer. Before fertilizing, the potting soil should be slightly dry, and it is best to loosen the soil first to aid fertilizer absorption. On the day after fertilizing, water once.

3. Repotting and soil changing: Osmanthus should be repotted and have its soil changed once every 2 to 3 years. Cut off some old roots and dead roots, place a layer of river sand or vermiculite at the bottom of the pot to improve aeration and drainage, and place decomposed cake fertilizer as a base fertilizer. The soil must be pressed firm when filling. The soil ratio is not very strict; usually garden soil, composted manure and river sand can each make up 1/3 of the mix.

4. Pruning and shaping: Osmanthus shaping generally adopts a combination of bending and pruning, and is best done after autumn. For plants with a very poor shape, the entire top branches can be cut off at the 2/3 or 3/4 point. Plants with overly dense branches should be thinned out. After flowering, water sprouts, dead branches, diseased and pest-infested branches, and dense weak branches should also be cut off.

5. Wintering management: For osmanthus in winter, the room temperature should be kept at 0 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, when sufficient sunlight is even more necessary. The following year, after Grain Rain, arrange for the potted osmanthus to be moved out of the room. After moving out, first place them together in a wind-sheltered, sunny spot outdoors so they gradually adapt to the outdoor environment.

6. Disease control: Common diseases of osmanthus include leaf spot, sooty mold, algal leaf spot, root rot and iron deficiency. 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, care should be taken to keep the soil loose and breathable, and avoid water accumulation.

7. Pest control: Common pests of osmanthus include sawflies, whiteflies, mites, white peach scale and yellow nettle caterpillars. Sawflies, whiteflies and mites can be killed by spraying 40% dimethoate 1500 to 3000 times solution. For white peach scale, besides manual brushing off, during the first and second instar nymph stages it can be killed by spraying 40% omethoate 1000 times solution or 40% fenitrothion 500 times solution.

What Varieties of Osmanthus Trees Are There?

1. Four Seasons Osmanthus varieties: Four Seasons Osmanthus is a clumping shrub with a low tree form, short and dense branches, and a rounded spherical crown. New leaves are dark red, while mature leaves are green or yellow-green. The leaves are elliptic to broadly ovate, and the angle between the main vein and side veins is very large, nearly perpendicular. It blooms in batches from September each year to the following March, and its floral fragrance is not as rich as that of Silver Osmanthus, Golden Osmanthus or Orange Osmanthus. Common varieties include Large-leaf Four Seasons Osmanthus and Small-leaf Four Seasons Osmanthus. Varieties that bloom in all four seasons include Yueyuegui, Rixianggui, Daye Fodingzhu and Chiyesijigui.

2. Orange Osmanthus variety group: Orange Osmanthus is dioecious, with a rounded spherical crown, light gray bark, relatively smooth, and sparse lenticels. Leaves are leathery, long elliptic or elliptic, with a relatively smooth leaf surface, revolute margins, entire margins, occasionally sparse teeth at the apex, a broad cuneate base, and an obtuse or shortly pointed apex. There are 8 to 10 pairs of side veins, the reticulate veins are obvious on both sides, and the petiole is 8 to 10 mm long. The flower color is orange-red, the corolla is slightly incurved, the fragrance is light, and the flowering period is from late September to early October. Varieties include Dahua Dangui, Chidangui, Zhusha Dangui and Kuanyehong.

3. Golden Osmanthus variety group: Golden Osmanthus has a rounded spherical crown, a strong tree vigor, and upright, very dense branches. The bark is gray, the lenticels are round or elliptic, and the spring shoots are relatively thick. The leaves are dark green, elliptic, with an uneven leaf surface and slightly wavy margins. The flower color is yellow, with a strong fragrance, and it does not set fruit. It blooms in autumn, with flowers ranging from lemon yellow to pale golden yellow. Varieties include Dahua Jingui, Dayehuang, Huangchuan Jingui, Wanjingui, Yuanye Jingui, Xianning Wangui, Qiugui, Yuanbian Jingui, Liuye Sugui, Jinshigui and Boye Jingui.

4. Silver Osmanthus variety group: Silver Osmanthus has a rounded spherical crown, spreading large branches, and dense branches and leaves. The bark is light gray, with many large lenticels shaped like snowflakes, very obvious. The leaves are green or dark green, long elliptic or elliptic, relatively broad and thick, with a relatively flat leaf surface. It blooms in early to mid-September, with flowers from creamy yellow to lemon yellow, a rich fragrance, and no fruit after flowering. It blooms in autumn. Varieties include Kuanyezi Yingui, Liuye Yingui, Yingye Yingui, Zi Yingui, Jiulonggui, Zao Yingui, Wan Yingui, Baijie, Chunbai Yingui and Qingshan Yingui.

What Should You Do If an Osmanthus Tree Does Not Bloom?

1. Moving indoors too early

[Cause] When the temperature is above 10°C, osmanthus moved indoors too early cannot get sufficient dormancy, causing it to sprout and unfold leaves too early, consuming a large amount of nutrients. Combined with insufficient light and a weakened plant, this affects flowering.

[Solution] Ensure low-temperature winter dormancy. The wintering temperature for potted osmanthus is 3 to 5°C. Above 3°C, it does not need to be moved indoors; keep it at natural temperature. Below 3°C, move it indoors. After moving indoors, let it dormant at low temperature, so that it can grow vigorously the next year with abundant flowers and leaves.

2. Moving outdoors too early

[Cause] After the osmanthus tree is moved outdoors in spring, wind and sun dry out the leaf tips, and even if new buds grow again, it is not easy for it to bloom.

[Solution] When moving it outdoors in spring, it should be moved out on a cloudy day or rainy day. Never move it outdoors on a hot sunny day and expose it to sudden sunlight. It should be allowed to gradually adapt to the outdoor environment.

3. Insufficient nutrients

[Cause] Osmanthus likes fertilizer. Some potted osmanthus are not repotted or given new soil for several years, resulting in insufficient nutrition. The root system becomes root-bound and cannot spread, affecting flowering.

[Solution] If the potting soil has been used too long, it should be replaced. Replace the potting soil once every 1 to 2 years. When repotting, a small amount of hoof pieces can be applied at the bottom of the pot as base fertilizer.

4. Insufficient light

[Cause] Osmanthus needs more than 10 hours of light; otherwise the leaves are not luxuriant, which affects flower bud formation and prevents flowering.

[Solution] Ensure long-day conditions. There should be more than 10 hours of sunlight per day to meet its sunlight needs.

5. Overwatering

[Cause] This causes root rot and leaf drop, affecting flowering.

[Solution] Water reasonably. The water content should be kept at 30%; in hot summer, a water content of 60% is suitable. Do not let it become too dry or too wet.

6. Too much nitrogen fertilizer

[Cause] Too much nitrogen fertilizer makes osmanthus branches and leaves grow excessively, affecting flowering.

[Solution] Nitrogen fertilizer should not be excessive, and should be applied together with phosphorus and potassium fertilizers. Osmanthus needs a lot of phosphorus and potassium fertilizer, so root-outside topdressing can be used, spraying leaves with 0.1 to 0.2% monopotassium phosphate.

7. Oil fume pollution

[Cause] Osmanthus is not tolerant of smoke, dust and oil stains. If leaves are polluted by smoke, dust and oil stains for a long time, growth is poor, and leaves may even fall off, affecting flowering.

[Solution] Prevent pollution. You can gently wipe the leaves with fine gauze to keep the leaf surface clean, wiping once every 15 days to facilitate photosynthesis and make the plant grow robustly.

8. Lack of pruning

[Cause] Osmanthus has a developed root system and strong sprouting ability. If it is not pruned moderately, the branches and leaves become too dense, affecting flowering.

[Solution] Prune appropriately. Before moving it outdoors, cut off diseased and weak branches and overly dense branches, and shorten them appropriately according to the plant shape, so as to improve ventilation and light penetration and promote flowering.