Two sources report 5 treatments between them. All are shown.
Protocol 1
DerivedN. C. Deno, 1996
Difficulty LowRated by us, not by the source.
Sow around September 2027 — a date the source gives, not one counted back from a May 3 last frost. Too late for spring 2027 — that needed starting on September 2026.
1
Sow outdoors and leave it
Sown outdoors in September; up in April.
No stated waiting before sowing. Then 210 days to germinate.
70% germination in 210 days.
This source doesn't state how long.
Protocol 2
DerivedN. C. Deno, 1996
Difficulty ModerateRated by us, not by the source.
Start around July 4, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on July 3, 2026.
1
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
2
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
3
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
about 9 months from start to sowing. Then 6 days to germinate.
80% germination in 6 days.
Protocol 3
DerivedN. C. Deno, 1993
Difficulty LowRated by us, not by the source.
Start around March 22, 2027 for a May 3 last frost.
1
Gibberellic acid soak
2
Sow and cover
Temperature: 70°F 21°C
No stated waiting before sowing. Then 14 days to germinate.
81% germination in 14 days.
Protocol 4
DerivedN. C. Deno, 1993
Difficulty ModerateRated by us, not by the source.
Start around September 23, 2026 for a May 3 last frost.
1
Gibberellic acid soak
2
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
3
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
about 6 months from start to sowing. Then 14 days to germinate.
95% germination in 14 days.
Protocol 5
DerivedN. C. Deno, 1993
Difficulty LowRated by us, not by the source.
Sow around September 2027 — a date the source gives, not one counted back from a May 3 last frost. Too late for spring 2027 — that needed starting on September 2026.
1
Sow outdoors and leave it
Sown outdoors in September; up in April.
No stated waiting before sowing. Then 210 days to germinate.