This source reports two treatments. Both are shown.
Protocol 1
DerivedN. C. Deno, 1993Difficulty Low Rated by us, not by the source.
Start around March 31, 2027 for a May 3 last frost.
- 1
Sow and cover
Temperature: 70°F 21°C · Light: dark
No stated waiting before sowing. Then 5 days to germinate.
90% germination in 3–5 days.
Deno reads the whole genus as a dark-at-70 germinator.
Protocol 2
DerivedN. C. Deno, 1993Difficulty Moderate Rated by us, not by the source.
Start around March 30, 2027 for a May 3 last frost.
- 1
Cold moist stratification
Temperature: 40°F 4°C
- 2
Warm moist stratification
Temperature: 70°F 21°C
Six seeds of eleven, in 2-6 days.
No stated waiting before sowing. Then 6 days to germinate.
55% germination in 2–6 days.
This source doesn't state how long.