Oenothera suffrutescens
This source reports two treatments. Both are shown.
Protocol 1
DerivedN. C. Deno, 1993Difficulty Very high
Start around September 17, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on September 16, 2026.
Cold moist stratification
Duration: 90 daysTemperature: 40°F 4°C
Warm moist stratification
Duration: 90 daysTemperature: 70°F 21°C
about 6 months from start to sowing. Germination time not stated; 21 days assumed.
2% germination.
Protocol 2
DerivedN. C. Deno, 1993Difficulty Very high
Start around September 17, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on September 16, 2026.
Warm moist stratification
Duration: 90 daysTemperature: 70°F 21°C
Cold moist stratification
Duration: 90 daysTemperature: 40°F 4°C
about 6 months from start to sowing. Germination time not stated; 21 days assumed.
1% germination.