- Type
- Herbs & Aromatics
- Difficulty
- Easy
- Season
- Spring·Summer
- Sowing
- From seed
Sweet wormwood
Artemisia annua
Artemisinin and essential oil · a fine-leaved annual of waste ground
Sweet wormwood comes up on its own across waste ground, roadsides and river banks. The leaves divide three times into something like lace, and rubbing one between your fingers releases a smell sharply unlike any other wormwood. The Korean name comes from that smell. Its familiar use is drying and pan-roasting the leaf for tea. From this plant's leaves came artemisinin, a sesquiterpene lactone, and the research that found it was awarded the 2015 Nobel Prize in Physiology or Medicine. What is used as a pharmaceutical, though, is a purified single compound, on entirely different terms and quantities from a tea brewed with leaves. The Donguibogam has an entry in the Herb section under 草蒿, with the Korean name given as jebissuk, and the original text states that this is 靑蒿; the prevailing modern view reads that as sweet wormwood. Whether the name stands for sweet wormwood as it is known today, however, cannot be settled.
Year-Round Calendar
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 4
- 5
- 6
- 7
- 8
Where It Grows
-
Main producer
Its homeland, and the largest producer. It is grown on a large scale for extraction in the hill country of Chongqing, Sichuan and Hubei. Harvest July, August
- 7
- 8
- Major producer Grown for extraction in the northern Red River Delta and the mountain districts.
- Major producer Grown in the cool climate of the central highlands.
- Major producer The growing area is the Arusha highlands in the north.
- Major producer Grown in the central highlands.
- Major producer Grown in the high-altitude southwest.
A plant of temperate Asia — northern China, more narrowly — now naturalised across the temperate world as far as Europe and North America. Production divides between China and the East African highlands because the compound content is higher in cool high country, and the African growing areas are new, arising only since the end of the twentieth century. In Korea and elsewhere it is gathered where it springs up on waste ground rather than planted in fields.
- Optimum
- 20~25℃
- Range
- 5~35℃
- Hardiness
- Not hardy
- Day length
- Short-day
An annual wormwood that comes up on its own in vacant lots and along riverbanks. It is a short-day plant, setting flower as the days shorten, so its flowering time shifts with latitude; at low latitudes the flower stalk rises early, while the plant is still short. On dry ground the scent turns strong, and with frequent water the leaves grow large but the scent thins. Frost kills it.
In Korea Nationwide
It comes up on its own on vacant lots, roadsides and riverbanks throughout the country. Sown in April–May, it is cut stem and all in June–August, before it flowers.
How to grow
- Light
- Full sun all day. In shade it runs tall with sparse leaves
- Soil and depth
- Not fussy. The scent is in fact stronger on lean, open ground
- Spacing
- 40 to 50cm between plants. It reaches head height, so crowding costs the lower leaves
- Watering
- Once established it needs no watering. Frequent water gives large leaves and a weaker scent
- Feeding
- No feeding. Rich ground runs the stems up until they fall
- Harvest
- June to August, cutting whole stems before flowering when the leaves are at their deepest green. After flowering the leaves thin out and the scent changes
What makes the difference. Wash the cut stems, shake them dry and dry them in the shade. Long spells in the sun drive off the compounds that carry the scent
Why this one is harder. The seed is minute, so a single plant is enough to bring it up all over the plot the next year. Cutting before it flowers is both how you get the tea and how you stop it spreading. It also sheds a lot of pollen, so anyone who reacts to daisy family pollen should keep flowering plants at a distance
Common problems
- Aphids You will see They mass on the shoot tips What to do Wash them off with a jet of water. These leaves go into tea, so use no sprays
- Spider mites You will see Leaves go dull and pale with very fine webbing What to do Spray water on the undersides too and keep it out of hot, dry corners
- Powdery mildew You will see A white dust settles on the lower leaves after the rainy season What to do Strip the lower branches for airflow and remove affected leaves
This page describes how a crop is grown and used. It does not claim health effects for any food, nor is it intended to prevent or treat disease. Component and study notes are references only and do not mean the same result occurs in people. Consult a medical professional about health concerns.
Health Benefits
The old record — choho (草蒿). The Donguibogam lists the plant in its Herb section as 草蒿 and gives the Korean name as jebissuk. It says the plant is found everywhere, and states that this is 靑蒿. It takes the spring air earliest; stem and leaf match ordinary mugwort, but this one is deeper green and therefore more strongly scented, and the deeper green is rated the better. This entry carries no line on nature or taste. Whether the name stands for sweet wormwood as known today cannot be settled, and what an old medical text wrote differs from how it is judged now.
The isolation of artemisinin. Artemisinin, a sesquiterpene lactone, was isolated from the leaves of sweet wormwood, and the research that found it was awarded the 2015 Nobel Prize in Physiology or Medicine. What is used as a pharmaceutical is a purified single compound, on different terms and quantities from a tea brewed with leaves cut in a field. This is a record about composition.
The range of content. Repeated analyses report that content varies widely with growing site, cutting time and drying method. No single figure can stand for a plant cut in a field. These are compositional analyses.
Nutrition
- Artemisinin (isolated from leaves and flower buds) — a sesquiterpene lactone obtained from sweet wormwood
- Essential oil (released when a leaf is rubbed) — the volatile fraction behind the distinctive smell
- Flavonoids (present in the leaves) — phenolic compounds reported widely across the genus Artemisia
The name artemisinin Artemisinin, a sesquiterpene lactone, was isolated from the leaves of sweet wormwood, and the research that found it was awarded the 2015 Nobel Prize in Physiology or Medicine. What is used as a pharmaceutical is a purified single compound, on different terms and quantities from a tea brewed with leaves. This entry stays with the compositional record.
Content shifts with growing conditions Analyses report that content varies widely with where the plant grew and when it was cut, even within sweet wormwood. That is why no single figure can be pinned to a plant cut in a field.
Essential oil and smell The smell released by rubbing a leaf comes from the volatile essential oil. Long exposure to sun drives it off and the smell fades, so leaves meant for tea are dried in the shade.
How much tea Brew the roasted leaf weak and keep it to a cup or two a day. Do not brew it strong and drink it all day in place of water. The bitterness is pronounced, so many people start by blending it with another tea.
Pairings
○ Shade drying and pan roasting — Wash the cut leaves, shake them dry, dry them in the shade and then roast them in a dry pan over low heat. Roasting takes off the green note and softens the bitterness.
○ Jujube and toasted brown rice — The bitterness is strong, so a few jujubes or some toasted brown rice in the pot makes it easier to drink. Use plenty of water and keep the steep short. Jujube
○ Hung in bunches — Cut stems tied in bunches were hung under eaves or by a window. The smell lingers as they dry. This is separate from its use as food.
△ Asteraceae allergy — Sweet wormwood belongs to the genus Artemisia in the daisy family. If you have ever reacted to mugwort or ragweed pollen, be careful with the tea as well, and start with a single weak mouthful. Some people get a rash on hands and arms from handling the leaves.
△ Pregnancy and breastfeeding — Do not drink sweet wormwood tea while pregnant or breastfeeding. Avoid strong infusions of Artemisia species generally, and do not give a child the same strength an adult would drink.
△ Where you cut, and ragweed confusion — Do not cut along roads, embankments or vacant lots, where herbicide and exhaust reach. Common ragweed, abundant on roadsides, has similarly finely divided leaves and is easy to confuse with sweet wormwood. Sweet wormwood gives a strong smell when rubbed, and differs from the perennial mugworts with white leaf undersides. Check smell and leaf underside together, and if you are not certain, do not cut.
Varieties
- Sweet wormwood (seed) — The finely divided annual wormwood. The species this entry covers
- Korean mugwort (division) — A perennial with larger leaves, white underneath. The one that goes into rice cakes and soup
- Jebissuk (Artemisia japonica) (seed) — A different species that carries the same Korean name written in the Donguibogam entry. Its leaves widen into spoon-shaped lobes
- Capillary wormwood (seed) — A perennial of gravelly ground by water. The stems persist through winter
Source: Donguibogam, Herb Section 草蒿 · Korea National Arboretum, Korean Plant Names Index