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 29, 2027 for a May 3 last frost.
- 1
Sow and cover
Temperature: 70°F 21°C
No stated waiting before sowing. Then 7 days to germinate.
80% germination in 5–7 days.
Protocol 2
DerivedN. C. Deno, 1993Difficulty Low Rated by us, not by the source.
Start around March 15, 2027 for a May 3 last frost.
- 1
Cold moist stratification
Temperature: 40°F 4°C
71% germinated at 40 itself.
- 2
Warm moist stratification
Temperature: 70°F 21°C
A further 12% after the move.
No stated waiting before sowing. Germination time not stated; 21 days assumed.
71% germination.
Either route works; sowing at 70 is faster.
This source doesn't state how long.