How do you grow osmanthus so it thrives? A detailed guide to the latest care methods

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

How do you grow osmanthus so it thrives?

1. Water at the right time: For osmanthus, follow the principle of not watering until the soil is dry, and watering thoroughly when you do, but spray the leaves with clean water once a day. After Qingming Festival, move the osmanthus to the open air and water it thoroughly once. In summer, water in the morning and evening; in winter, water around midday so the water temperature is close to the soil temperature and there is no sudden cold or heat. Be careful not to let water accumulate.

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

3. Repot and change the soil: Every 2-3 years, osmanthus should be repotted and given fresh soil. Trim away some old roots and dead roots, line the bottom of the pot with a layer of river sand or vermiculite to improve aeration and drainage, and place decomposed cake fertilizer as a base fertilizer. Be sure to press the added soil down firmly. The soil mix ratio is not very strict; usually garden soil, composted manure and river sand can be mixed at 1/3 each.

4. Pruning and shaping: Osmanthus is generally shaped by a combination of bending and pruning, preferably done in autumn. For plants with a very poor shape, cut off all the top branches at 2/3 or 3/4 of the height. For plants with overly dense branches, thin them out. After flowering, also cut off leggy branches, dead branches, diseased and pest-damaged branches, and dense weak branches.

5. Winter management: For overwintering osmanthus, the room temperature should be kept at 0-5°C and relative humidity at 50-80%. A cold room in winter should have good light; especially before the buds begin to swell in early spring, even more sunlight is required. The following year, after Grain Rain, arrange for potted osmanthus to be moved outdoors. After moving out, first place them together in a sheltered, sunny spot outdoors so they gradually adapt to the outdoor environment.

6. Disease control: Common osmanthus diseases include leaf spot, sooty mold, algal leaf spot, root rot and iron deficiency. For leaf spot, sooty mold and algal leaf spot, spray 0.5 Bordeaux mixture or 5% carbendazim at 500-1000 times dilution. For root rot, keep the soil loose and aerated and do not let water accumulate.

7. Pest control: Common osmanthus pests include sawflies, whiteflies, mites, white peach scale and yellow slug moths. Sawflies, whiteflies and mites can be killed by spraying 40% dimethoate at 1500-3000 times dilution. For white peach scale, besides brushing them off by hand, you can spray 40% omethoate at 1000 times dilution or 40% fenitrothion at 500 times dilution when the first and second instar nymphs appear.

What varieties of osmanthus tree are there?

1. Four Seasons Osmanthus group: Four Seasons Osmanthus is a clumping shrub with a low tree form, short and dense branches, and a round spherical crown. New leaves are dark red, and mature leaves are green or yellow-green. The leaves are elliptical to broadly ovate, and the angle between the midrib and side veins is very large, approaching perpendicular. It blooms in batches from September each year to the following March, and the fragrance is not as rich as that of Silver Osmanthus, Golden Osmanthus or Red Osmanthus. Common varieties include Large-leaf Four Seasons Osmanthus and Small-leaf Four Seasons Osmanthus; varieties that bloom in all four seasons include Yueyue Gui, Rixiang Gui, Large-leaf Foding Zhu and Serrated-leaf Four Seasons Osmanthus.

2. Red Osmanthus variety group: Red Osmanthus is dioecious, with a round spherical crown. The bark is light gray, relatively smooth, with sparse lenticels. The leaves are leathery, long elliptical or elliptical, with a relatively smooth surface, revolute margins, entire edges, occasionally sparse teeth at the tip, a broad wedge-shaped base, and a blunt or short-pointed apex. There are 8-10 pairs of side veins, the reticulate veins are obvious on both sides, and the petiole is 8-10 mm long. The flower color is orange-red, the corolla is slightly incurved, the fragrance is faint, and the flowering period is from late September to early October. Varieties include Large-flower Red Osmanthus, Serrated Red Osmanthus, Cinnabar Red Osmanthus and Broad-leaf Red.

3. Golden Osmanthus variety group: Golden Osmanthus has a round spherical crown, strong vigor, and upright, very dense branches. The bark is gray, with round or elliptical lenticels, and the spring shoots are relatively thick. The leaves are dark green, elliptical, with an uneven surface and slightly wavy margins. The flowers are yellow, strongly fragrant, and the plant does not set seed. It blooms in autumn, with flowers ranging from pale lemon yellow to golden yellow. Varieties include Large-flower Golden Osmanthus, Large-leaf Yellow, Huangchuan Golden Osmanthus, Late Golden Osmanthus, Round-leaf Golden Osmanthus, Xianning Late Osmanthus, Ball Osmanthus, Round-petal Golden Osmanthus, Willow-leaf Su Osmanthus, Jinshi Osmanthus and Wave-leaf Golden Osmanthus.

4. Silver Osmanthus variety group: Silver Osmanthus has a round spherical crown, spreading large branches, dense branches and leaves, light gray bark, and numerous large lenticels shaped like snowflakes that are very conspicuous. The leaves are green or dark green, long elliptical or elliptical, relatively broad and thick, with a relatively flat surface. It blooms in early to mid-September, with flowers from creamy yellow to lemon yellow, a rich fragrance, and no seed set after flowering. It blooms in autumn. Varieties include Broad-leaf Seed Silver Osmanthus, Willow-leaf Silver Osmanthus, Hard-leaf Silver Osmanthus, Seed Silver Osmanthus, Jiulong Gui, Early Silver Osmanthus, Late Silver Osmanthus, Baijie, Pure White Silver Osmanthus and Qingshan Silver Osmanthus.

What should you do if your osmanthus tree does not bloom?

1. Moving indoors too early

[Cause] When the temperature is above 10°C, moving osmanthus indoors too early prevents it from getting enough dormancy, causing it to sprout and leaf out too early and consume large amounts of nutrients. Combined with insufficient light and a weakened plant, this affects flowering.

[Solution] Ensure low-temperature winter dormancy. For potted osmanthus, the overwintering temperature should be 3-5°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 remain dormant at low temperature; only then can it grow vigorously the next year with abundant flowers and lush 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 emerge, it is not easy for it to flower.

[Solution] In spring, move it outdoors on a cloudy or rainy day. Never move it out suddenly on a hot sunny day and expose it to intense sun; let it gradually adapt to the outdoor environment.

3. Insufficient nutrients

[Cause] Osmanthus likes fertilizer. Some potted osmanthus are not repotted or given fresh soil for several years, resulting in insufficient nutrients and roots that are bound and cannot spread, which affects flowering.

[Solution] If the potting soil has been in place too long, repot and change the soil once every 1-2 years. When repotting, apply a small amount of hoof pieces at the bottom of the pot as a base fertilizer.

4. Insufficient light

[Cause] Osmanthus needs more than 10 hours of light; otherwise the leaves are not lush and flower bud formation is affected, so it does not bloom.

[Solution] Ensure long-day conditions, with 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 sensibly: maintain about 30% moisture content, and in hot summer about 60% is suitable. Do not let it get too dry or too wet.

6. Too much nitrogen fertilizer

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

[Solution] Do not use too much nitrogen fertilizer; apply it together with phosphorus and potassium fertilizers. Osmanthus needs plenty of phosphorus and potassium fertilizer, and can be given as a foliar feed by spraying 0.1-0.2% monopotassium phosphate on the leaves.

7. Cooking fume pollution

[Cause] Osmanthus does not tolerate soot and greasy dirt. If the leaves are polluted by soot and greasy dirt for a long time, growth is poor and leaves may even drop, 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 aid photosynthesis and keep the plant growing vigorously.

8. Lack of pruning

[Cause] Osmanthus has a well-developed root system and strong sprouting ability. Without moderate pruning, 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 branches appropriately according to the plant's shape, so as to improve ventilation and light penetration and encourage flowering.