Spiny annual thistle with yellow flower heads. Traditional digestive bitter and galactagogue; different from milk thistle despite the similar common names.
Hardiness ratings
| System | Rating | Temperature range | How to read it |
|---|---|---|---|
| USDA hardiness zone | Zone 4–8 | −34.4 °C to −6.7 °C | Zones where it can be grown as an annual — not a frost-tolerance rating |
| RHS hardiness rating | H7 | down to −20 °C | Plant needs at least this level of cold tolerance |
| Canadian plant hardiness zone | Zone 4–8 | −29 °C to −1 °C | Zones where it can be grown as an annual — not a frost-tolerance rating |
| Australian (ANBG) zone | Zone 1–4 | −15 °C to 5 °C | Zones where it can be grown as an annual — not a frost-tolerance rating |
As a tender annual, Blessed thistle (Holy thistle) doesn't overwinter — the zone range shows where the growing season supports it. See the RHS rating for its actual cold tolerance.
Growing notes
- Different plant from milk thistle (Silybum marianum) — different genus, different uses
- Always consult a qualified medical or herbal practitioner before using any plant medicinally
Categories
Related plants
Cross-check Blessed thistle (Holy thistle) against your zones