Xanthoceras sorbifolium, Yellowhorn, Chinese flowering chestnut, 10 seeds
Xanthoceras sorbifolium (zan-tho-KER-as sor-bee-FOH-lee-um), Yellowhorn, Shiny leaf yellowhorn, Goldenhorn, Chinese flowering chestnut, is a species of flowering plant in the soapberry family Sapindaceae, and the only species in the genus Xanthoceras. It is native to northern China.
It is a large deciduous shrub or small tree growing to 8 m tall. The leaves are arranged alternately, 12–30 cm long, and are pinnate, with 9–17 leaflets, the leaflets 3–6 cm long, with a sharply serrated margin. The flowers are 2–3 cm in diameter, with five white petals, and are produced in erect panicles 10–20 cm long in mid spring. The fruit is an oval leathery capsule 5–6 cm diameter, which splits into three sections at maturity to release the 6–18 seeds; the seeds are black, 1.5 cm in diameter, resembling a small horse chestnut seed.
The genus name Xanthoceras (which translates as "yellow horn") is considered to be the most basal member of the family Sapindaceae. The specific epithet sorbifolium refers to the leaves, which resemble those of the distantly related rowans (Sorbus).
Xanthoceras sorbifolium grows best when planted in an area with full sun. Ideally, the soil should be well-drained and loamy. However, this shrub is highly adaptable to multiple environments so it can readily be grown in partial shade, damp soils, and even tolerate some drought.
Chances of successful cultivation are best in zones four through seven but may still require some sheltering during the winter to prevent the shrub from cold drying.
Some sources state that Yellowhorn is self-fertile and some say that it requires cross-pollination. Likely, it is partially self-pollinating but will produce significantly more fruit if allowed to cross-pollinate. It is reported that there are both male flowers and bisexual (hermaphroditic) flowers found on the same plant, but not the same inflorescence.
Flowering: Mid-Late Spring to Early Summer (April-June)
Yellowhorn plant grown from seed will reward you with flowers at early age, sometimes on the second year, from most sources on third. It will take 10-20 year to reach its maximum height of 7-8 meters.
Maximum yield will start at around 5 years of age. No reliable information can be found, but one source stated that Yellowhorn can live for over 200 years of age.
Xanthoceras sorbifolium is typically used as a border plant due to its large size. It also makes a great specimen tree/shrub that can be used to provide shade when located close to a patio.
It's a relatively low-maintenance shrub that requires little to no pruning. Any pruning should be done between the late winter and early spring. Insects, diseases and other plant problems: Coral spot fungus can occur, particularly when the wood is not fully ripened, and the plant is exposed to a late frost.
In cultivation in the UK, X. sorbifolium has gained the Royal Horticultural Society's Award of Garden Merit. It is fully hardy but prefers a sheltered position.
The leaves, flowers, and seeds of yellowhorn are all edible.
Sowing time: late autumn in soil or the pots outside, spring (in winter plant goes dormant, it’s not recommended to start the seeds in summer)
Germination temperature: 20-22°C
Pre-Treatment: Scarification (rub the seeds against the sand paper, do not penetrate the embryo). Soak in lukewarm water for 48 h.
Some sources recommend poring hot water (50-60 °C, higher temperature can kill the seeds) over the seeds and soak them in the same water for 24-48 hour, but this method wasn’t tested myself personally.
3 month stratification (cold treatment at 2-4 °C in the fridge) improves the germination rate, but not necessary. Seeds may start germinating in the fridge. Then you can take them to the room temperature to continue the process.
If sowing outdoors in autumn the seeds will go through stratification naturally
Sowing mix: compost for seeds and cuttings + sand or perlite. Some sources recommend using the compost for acidic loving plants with PH level between 4-5.
Water: keep moist, not wet
Germination time: 2-4 weeks