Artichoke (Imperial Star)
perennial
- 2026 · Bed E
- Spacing
- 36 in
- Trellis
- no
- Seed indoor
- Jan 21(-12 w)
- Transplant
- Apr 15(at frost)
- Harvest
- ~20–28 weeks from sowing
- Water
- 1-2 per week
- Seed shelf life
- 5–6 y
- Lifecycle
- perennial
- Seed source
- Johnny's Selected Seeds
Imperial Star and Colorado Star are bred for first-year production from seed. Needs ~10 days of 45-50°F to trigger budding — happens naturally in a cool Zone 7 spring, or chill seedlings in the fridge for 10 days before planting out. Plant 1 per 9 sqft (3 ft spacing). Perennial in mild climates, treated as annual where winter lows go below ~14°F.
First-year-from-seed artichoke. Imperial Star is the green variety on one side of Bed E, paired with Colorado Star (purple) on the other side.
Imperial Star is bred specifically for annual production from seed — it doesn’t need a Zone 8+ winter to set buds. The trick is the cold treatment: ~10 days at 45-50°F to trigger flowering, which happened naturally during the cool spring. Started indoors in late January, hardened off, transplanted in early April.