Isatis tinctoria | ‘Asp of Jerusalem’, ‘Dyer’s Woad’, ‘Glastum’, ‘Woad’ | 25 seeds
Isatis tinctoria (syn. Isatis indigotica, Isatis japonica) is an herbaceous flowering species of the Brassicaceae family. Known informally by names including ‘Asp of Jerusalem’, ‘Dyer’s Woad’, ‘Färberwaid’, ‘Glastum’, ‘Thüringer Waid’ and (most often) ‘Woad’, the plant is originally native to parts of Asia, the Caucasus and Eastern Siberia, although is now naturalised to large parts of Europe and Northern America too.
A smooth-foliaged and shrubby biennial herb which reaches a maximum height of roughly one hundred and twenty centimetres or so by approximately fifty centimetres across, Isatis tinctoria is an insect-pollinated, hermaphroditic species which produces sweetly-scented, yellow to golden blooms between late spring and late summer.
Medicinally, the roots of tinctoria have been used by traditional Chinese herbalists for many hundreds of years. The name ‘Woad’ also refers to the useful, blue-coloured dye – famously applied as body paint by some ancient Britons, such as those we call the Picts, or Celts (its use dates back to at least the Neolithic) – which can be extracted from the leaves of this species by means of a complex fermentation method. More recently, there have been experiments growing the plant for use as a wood preservative, plus an increasing use of the plant’s products as an environmentally-safe, biodegradable ingredient in commercial dyes and inks.
Naturally occurring in fertile, well-drained habitats in USDA Hardiness Zones 4-9, tinctoria prefers neutral to alkaline soils, often growing on cliffs and in cornfields where the minimum temperature is roughly -15°C (59°F). Sow the seed in moist, sandy to loamy soil and you should be rewarded with your first flowers at around a year and a half from planting. Space young plants at least sixty centimetres apart, so that they have enough room to reach their mature size. Note that this species is considered invasive in several regions, plus needs rotating to a new site every two years, maximum, due to its voracious appetite for soil nutrients!
All the seed sold by Arkham’s Botanical was freshly and ethically sourced