Dyer’s alkanet

Alkanna tinctoria

Bristly Mediterranean perennial with bright blue forget-me-not-like flowers and a deep purple-red taproot. The root yields a fat-soluble red pigment used for soap, lip salves, oils, and food colouring.

Hardiness ratings

Dyer’s alkanet hardiness across the four zone systems
SystemRatingTemperature rangeHow to read it
USDA hardiness zone Zone 6–9 −23.3 °C to −1.1 °C Plant tolerates down to this zone
RHS hardiness rating H5 −15 °C to −10 °C Plant needs at least this level of cold tolerance
Canadian plant hardiness zone Zone 6–8 −18 °C to −1 °C Plant tolerates down to this zone
Australian (ANBG) zone Zone 2–6 −10 °C to 15 °C Plant tolerates down to this zone

Growing notes

  • Red pigment (alkannin) extracted from the dried root — fat-soluble rather than water-soluble, so used as an oil and wax colourant rather than as a textile dye
  • Used historically and still today to colour the rich red of high-end lipsticks, beeswax salves, and certain Italian olive oils
  • Drought tolerant — natural on stony Mediterranean hillsides
  • Distinct from the boraginaceous “alkanet” Anchusa officinalis, which produces little useful dye

Categories

Related plants

Cross-check Dyer’s alkanet against your zones

Reference

Dyer’s alkanet on Wikipedia