- Type
- Herbs & Aromatics
- Difficulty
- Moderate
- Season
- Spring·Fall
- Sowing
- From seed
Purple gromwell
Lithospermum erythrorhizon
Shikonin · a root that stains everything red
Purple gromwell is a perennial of the borage family whose root leaves violet on the hands the moment it is lifted. That colour comes from shikonin, a naphthoquinone pigment held in the root bark. It was the dye that coloured purple cloth in Korea for centuries, and it still turns up as a natural colourant and a cosmetics ingredient. Hongju, the liquor of Jindo in South Jeolla province, takes its red by running freshly distilled soju through gromwell root, and it remains the best-known living use. The Donguibogam lists it in the Herb section as jacho ("purple herb"), records the Korean name as jichi, and states plainly that it is the same jacho then used to dye things purple. It notes that the plant grows across hills and fields, and gives the handling: lift the root in the third month of the lunar calendar, dry it in the shade, wash it with liquor before use. Wild gromwell has declined sharply and is not a plant to dig at will, and raising it from seed is difficult from germination onward. Rather than brewing the root long and drinking it daily, using a small amount for colour stays far closer to what this material has always been for.
Year-Round Calendar
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 3
- 4
- 10
- 11
Where It Grows
- Main producer In Northeast China (Dongbei) — Heilongjiang, Liaoning and Jilin — this species is dug and grown under the name yingzicao. That said, most of what passes in China today as zicao is the Xinjiang plant Arnebia euchroma, which belongs to a different genus.
-
Wild population
It grows wild in sunny, dry grassland along mountain foothills throughout the country, but numbers have fallen sharply. Small quantities are cultivated in places such as Jindo in South Jeolla. Harvest October, November
- 10
- 11
- Wild population Under the name murasaki it once grew wild in the grasslands of Honshu and southward, but wild plants are now rare and the species is protected.
Its origin and range is the temperate belt of East Asia, spanning Korea, northeastern China and Japan. In all three countries wild plants have grown scarcer, and the crop is moving from wild harvest to cultivation. Much of what circulates in the market under the name jacho is in fact a plant of a different genus (Arnebia euchroma) from the arid northwest of China, so the two species should be kept apart when both are shaded onto a single map.
- Optimum
- 15~22℃
- Range
- 5~28℃
- Hardiness
- Hardy
This is a plant of dry, sunny slopes with free-draining soil. It takes cold well but suffers in the damp of the summer rainy season; where water collects, the rot starts at the root. The cooler and drier the site, the deeper the colour that settles into the root.
Harvested 2–3 years after planting. In the year it is sown, the root stays thin. It is grown for two or three years and then lifted in autumn, so the year of sowing and the year of harvest are not the same.
In Korea Nationwide
It grows wild on sunny, dry slopes in mountains across the country. Sites where water pools in summer are difficult to farm, so it is planted where the rain can be kept off.
How to grow
- Light
- A dry slope in sun all day. In shade and damp the root rots
- Soil and depth
- Sharply draining soil cut with coarse grit, at least 30cm deep. The root runs straight down, so use a deep pot
- Spacing
- 20 to 25cm between plants. The foliage stays modest, but leave room for the root
- Watering
- Watch it only until it has rooted. After that keep it on the dry side
- Feeding
- A little compost as a base dressing, no more. Fed heavily it makes leaf and the root takes less colour
- Harvest
- Lift in October or November, after the leaves die back on a plant two or three years old. The Donguibogam gives the third month of the lunar calendar. The root runs straight and deep, so dig wide from the side and lift the whole thing out
What makes the difference. Do not soak the lifted root; knock off the soil and dry it in the shade. Since the pigment dissolves in alcohol and oil rather than water, use liquor or oil to draw the red out
Why this one is harder. Germination is slow and uneven, and the root needs two or three years before it takes colour. It cannot stand a wet position, and a single rainy season can take the whole plant. A pot kept somewhere sheltered from rain is the surer route
Common problems
- Root rot You will see Leaves yellow, the plant collapses, and the lifted root is soft What to do Avoid ground where water stands and raise the ridge. In a pot, lengthen the interval between waterings considerably
- White grubs You will see Chewed patches on the root and holes visible at lifting What to do Turn the soil before planting and pick out the larvae; never dig in half-rotted compost
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 — jacho (紫草). The Donguibogam lists it in the Herb section as jacho ("purple herb") and records the Korean name as jichi. It sets down a cold nature (neutral by another account), a bitter taste (sweet by another account), and no toxicity. On provenance it says the plant grows across hills and fields and is found everywhere, and it states that this is the same jacho then used to dye things purple, identifying it with the dye plant. It gives the handling as well: lift the root in the third month of the lunar calendar, dry it in the shade, and wash it with liquor before use. This is a historical medical record and differs from modern judgment.
Analyses of shikonin. Repeated analyses report the isolation of shikonin and acetylshikonin from gromwell root bark. They are red naphthoquinone pigments, and the same work records that they dissolve far better in alcohol and oil than in water. This is an analysis of composition and has nothing to do with preventing or treating disease.
Nutrition
- Shikonin (the red pigment of the root bark) — a naphthoquinone pigment
- Acetylshikonin (found alongside shikonin) — a derivative of the same class
- Pyrrolizidine alkaloids (reported across several borage-family species) — a compound class regulated in food in Europe
Where the red comes from The violet of the gromwell root comes from shikonin, a naphthoquinone pigment in the root bark, with derivatives such as acetylshikonin found alongside it. It dissolves readily in alcohol and oil but poorly in water, which is why liquor or oil has always been the medium for drawing the colour out. This entry stays with the compositional record.
The borage family and pyrrolizidine alkaloids Several species in the borage family, to which gromwell belongs, carry pyrrolizidine alkaloids, and Europe regulates that compound class as a food residue. That is the reason for not brewing the root long and drinking it daily. Keep to small amounts used for colour.
A dyeing material Gromwell root was the dye behind purple cloth, and it still serves as a natural colourant and a cosmetics ingredient. The red of Jindo hongju comes from this root. It stains hands and boards straight through, so handle it in gloves.
Pairings
○ Liquor — Jindo hongju — Hongju, from Jindo in South Jeolla province, takes its red by running freshly distilled soju through gromwell root. It puts the pigment's solubility in alcohol to work directly. Running the spirit through gives a clearer colour than steeping the root for a long time.
○ Oil — Shikonin dissolves well in oil, so dried root left standing in oil bleeds red into it. This is the route by which the material has been handled for salves and cosmetics.
○ Natural dyeing — Break dried root up small and steep it in warm alcohol or lye water to draw the violet out. The mordant decides where the colour lands, anywhere from purple to red-violet.
△ Brewing it and drinking it daily — Several species in the borage family carry pyrrolizidine alkaloids, and Europe regulates that compound class as a food residue. Do not brew the root long and take it day after day. Keep to small amounts used for colour, and put questions about medicinal use to a Korean medicine doctor or a pharmacist.
△ Digging wild roots — Digging a wild gromwell root ends that plant, and native populations have fallen sharply. Digging on someone else's hillside or on public forest land is barred by law as well. Buy cultivated material if you need it, and start from seed if you want to grow it.
△ Stained hands and boards — Gromwell root leaves violet on hands, boards and clothes. Wear gloves and work on glass or stainless steel rather than a wooden board. The pigment dissolves in alcohol, so alcohol lifts the stain better than water.
Varieties
- Purple gromwell (wild) — The native species. A thick root with deep violet colour; this is the one used for dyeing
- Corn gromwell (wild) — A different species in the same family whose root is not red. No use where colour is the point
- Lithospermum zollingeri (wild) — A native species with blue spring flowers. Its root is not red either
- Arnebia root (imported) — The root of a different genus used as 紫草 in China. It sometimes turns up mixed into imported material
Source: Donguibogam, Herb Section 紫草 · Korean Plant Names Index