This source reports three treatments. All are shown.
Protocol 1
DerivedN. C. Deno, 1993
Difficulty ModerateRated by us, not by the source.
Start around January 25, 2027 for a May 3 last frost.
1
Cold moist stratification
Temperature: 40°F 4°C
Seven of fifteen, over 5-10 weeks -- it germinates in the cold.
2
Warm moist stratification
Temperature: 70°F 21°C
Five more of fifteen, in 1-3 days.
No stated waiting before sowing. Then 70 days to germinate.
47% germination in 35–70 days.
Seven seeds of fifteen in the cold, five more after the move. The best of three. Deno's samples were small and he does not call the GA-3 differences significant.
This source doesn't state how long.
Protocol 2
DerivedN. C. Deno, 1993
Difficulty ModerateRated by us, not by the source.
Start around March 16, 2027 for a May 3 last frost.
1
Gibberellic acid soak
2
Sow and cover
Temperature: 70°F 21°C · Light: dark
No stated waiting before sowing. Then 20 days to germinate.
39% germination in 3–20 days.
Seven seeds of eighteen. The only Wyethia here that GA-3 did not kill. Deno's samples were small and he does not call the GA-3 differences significant.
Protocol 3
DerivedN. C. Deno, 1993
Difficulty HighRated by us, not by the source.
Start around March 15, 2027 for a May 3 last frost.
1
Sow and cover
Temperature: 70°F 21°C
No stated waiting before sowing. Then 21 days to germinate.
17% germination in 21 days.
Two seeds of twelve sown warm and left alone. Deno's samples were small and he does not call the GA-3 differences significant.