Qing Hao, Sweet sagewort
Artemisia annua
Family: Asteraceae or Compositae
What it is like
Artemisia annua is a ANNUAL growing to 3 m (9ft) by 1 m (3ft 3in) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 7. It is in flower from August to September, and the seeds ripen from September to October. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects. Suitable for: light (sandy) and medium (loamy) soils, prefers well-drained soil and can grow in nutritionally poor soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers dry or moist soil.
Height (m): 3
Where it is found
Occurs naturally as part of a steppe vegetation in the northern parts of Chahar and Suiyuan provinces in China, at 1000 to 1500 m above sea level.
S. E. Europe to W. Asia.
Conservation Status: This taxon has not yet been assessed.
Countries/locations it is found in
How it is used
Food
Rating: 1
An essential oil in the leaves is used as a flavouring in spirits such as vermouth.
Condiment: the various plants that are used as flavourings, either as herbs, spices or condiments.
Medicine
Rating: 4
Qing Ho, better known in the West as sweet wormwood, is a traditional Chinese herbal medicine. An aromatic anti-bacterial plant, recent research has shown that it destroys malarial parasites, lowers fevers and checks bleeding. It is often used in the Tropics as an affordable and effective anti-malarial. The leaves are antiperiodic, antiseptic, digestive, febrifuge. An infusion of the leaves is used internally to treat fevers, colds, diarrhoea etc. Externally, the leaves are poulticed onto nose bleeds, boils and abscesses. The leaves are harvested in the summer, before the plant comes into flower, and are dried for later use. The plant contains artemisinin, this substance has proved to be a dramatically effective anti-malarial against multi-drug resistant Plasmodium spp. Clinical trials have shown it to be 90% effective and more successful than standard drugs. In a trial of 2000 patients, all were cured of the disease. The seeds are used in the treatment of flatulence, indigestion and night sweats.
Antibacterial: Kills bacteria.
Antiperiodic: Counteracts recurring illnesses such as malaria.
Antiseptic: Preventing sepsis, decay or putrefaction, it destroys or arrests the growth of micro-organisms.
Carminative: Reduces flatulence and expels gas from the intestines.
Digestive: Aids digestion.
Febrifuge: Reduces fevers.
Malaria: Treats malaria - an acute febrile illness caused by Plasmodium parasites spread to people through the bites of mosquitos.
Miscellany: Various medicinal actions that need more clarification.
Other
Rating: 2
The plant is used in China as a medium for growing Aspergillus which is used in brewing wine. The substances mentioned above in the medicinal uses, used in the treatment of malaria, also show marked herbicidal activity. The plant yields 0.3% essential oil. This has an agreeable, refreshing and slightly balsamic odour and has been used in perfumery.
Essential: Essential oils that are used in perfumery, medicines, paint solvents, insect repellents etc.
Herbicide: Plants or plant extracts that can inhibit the growth of other plants.
Miscellany: A rag-bag of items that are difficult to categorise.
Scented Plants: Plants noted for their scent
How it is grown
An easily grown plant, succeeding in a well-drained circumneutral or slightly alkaline loamy soil, preferring a sunny position. Plants are longer lived, more hardy and more aromatic when they are grown in a poor dry soil. A fast-growing annual plant, it is tall but neat in habit with a handsome fragrant foliage and is useful for filling gaps at the back of a border. It has become a weed of waste places in many areas of the world. The plant is extremely vigorous and essentially disease and pest free. Qing Hao is a determinate short-day plant. Non-juvenile plants are very responsive to photoperiodic stimulus and flower about two weeks after induction. The critical photoperiod seems to be about 13.5 hours, but there are likely to be photoperiod x temperature interactions. In Lafayette Indiana, USA (40°21'N) plants flower in early September with mature seeds produced in October. The plant is not adapted to the tropics because flowering will be induced when the plants are very small. Most collections of artemisia derive from natural stands with highly variable artemisinin content, some as low of 0.01%. Selections from Chinese origin vary from 0.05 to 0.21%. Swiss researcher N. Delabays reports a clonal selection derived from Chinese material which produces 1.1% artemisin but is very late flowering; proprietary hybrids have been obtained with somewhat lower content but flower earlier. Members of this genus are rarely if ever troubled by browsing deer.
Propagating it: Seed - sow spring in a cold frame and plant out in late spring or early summer. Alternatively, the seed can be sown late spring in situ.
Best place to grow: Cultivated Beds;
Habit: Annual
Hardiness: 6-9
Growth: Fast
Soil: Light (sandy), medium
Shade: Semi-shade, no shade
Moisture: Dry, moist
Things to keep in mind
Skin contact with the plant can cause dermatitis or other allergic reactions in some people. The pollen is extremely allergenic.
This plant can be weedy or invasive. Some evidence it is weedy in Kentucky, USA.