About the plant
What it is and where it grows — not part of any germination protocol.
The plant
- Habit
- Herbaceous perennialPlant Finder
- Habit
- Perennial, Forb/herbPLANTS Database
- Height
- 1.5-2 ftPlant Finder
- Spread
- 1.5-2 ftPlant Finder
- Flower
- Showy, fragrant; crimson redPlant Finder
- Blooms
- MayPlant Finder
- Native range
- EuropePlant Finder
- Hardiness zones
- 8-10Plant Finder
- Note
- Nicking the seed, reported to help in the first edition, did not hold up. GA-3 gave only a small gain.Seed Germination Theory and Practice, 2nd ed.
- Note
- Relatively pest free. Botrytis and Phytophthora blight are the usual trouble.Plant Finder
Growing conditions
- Sun
- Full sun to part shade
- Soil
- Rich, fertile, moist, well-drained
- Watering
- Medium
Toxicity is noted only where a source states it. No note here is not a finding of safety.
Sources: Plant Finder — Missouri Botanical Garden; PLANTS Database — USDA NRCS; Seed Germination Theory and Practice, 2nd ed. — N. C. Deno.
This source reports 6 treatments. All are shown.
Protocol 1
DerivedN. C. Deno, 1993Difficulty Low Rated by us, not by the source.
Start around November 12, 2026 for a May 3 last frost. Too late for spring 2027 — that needed starting on November 11, 2025.
- 1
Dry storage
Duration: 180 days · Temperature: 40°F 4°C
- 2
Warm moist stratification
Temperature: 70°F 21°C
The radicle and its branching root system form here. This is what Deno counts as germination.
- 3
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
- 4
Warm moist stratification
Temperature: 70°F 21°C
The single true leaf forms only now. Germination is hypogeal.
about 9 months from start to sowing. Then 240 days to germinate.
100% germination in 90–240 days.
Every seed. Six months dry at 40 first, then simply warmth -- and patience.
This source doesn't state how long.
Protocol 2
DerivedN. C. Deno, 1993Difficulty Low Rated by us, not by the source.
Start around November 12, 2026 for a May 3 last frost. Too late for spring 2027 — that needed starting on November 11, 2025.
- 1
Dry storage
Duration: 180 days · Temperature: 70°F 21°C
- 2
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
- 3
Warm moist stratification
Temperature: 70°F 21°C
The radicle and its branching root system form here. This is what Deno counts as germination.
- 4
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
- 5
Warm moist stratification
Temperature: 70°F 21°C
The single true leaf forms only now. Germination is hypogeal.
about 12 months from start to sowing. Then 150 days to germinate.
94% germination in 90–150 days.
Stored at 70 the seed does better started cold: 94%, against 63% started warm.
This source doesn't state how long.
Protocol 3
DerivedN. C. Deno, 1993Difficulty Low Rated by us, not by the source.
Start around December 12, 2026 for a May 3 last frost. Too late for spring 2027 — that needed starting on December 11, 2025.
- 1
Dry storage
Duration: 180 days · Temperature: 40°F 4°C
- 2
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
- 3
Warm moist stratification
Temperature: 70°F 21°C
The radicle and its branching root system form here. This is what Deno counts as germination.
- 4
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
- 5
Warm moist stratification
Temperature: 70°F 21°C
The single true leaf forms only now. Germination is hypogeal.
about 12 months from start to sowing. Then 120 days to germinate.
85% germination in 60–120 days.
Faster than the 100% route by a couple of months, and fifteen points worse.
This source doesn't state how long.
Protocol 4
DerivedN. C. Deno, 1993Difficulty Moderate Rated by us, not by the source.
Start around December 6, 2026 for a May 3 last frost.
- 1
Warm moist stratification
Temperature: 70°F 21°C
67% here, in the fourth month. The radicle and its branching root system form here. This is what Deno counts as germination.
- 2
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
A further 12%.
- 3
Warm moist stratification
Temperature: 70°F 21°C
A further 6%. The single true leaf forms only now. Germination is hypogeal.
Steps after step 1 run on after germination.
No stated waiting before sowing. Then 120 days to germinate.
67% germination in 120 days.
Fresh seed: 67% in the fourth month, then 12% and 6% over the next two cycles.
This source doesn't state how long.
Protocol 5
DerivedN. C. Deno, 1993Difficulty Moderate Rated by us, not by the source.
Start around July 16, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on July 15, 2026.
- 1
Dry storage
Duration: 180 days · Temperature: 70°F 21°C
- 2
Warm moist stratification
Temperature: 70°F 21°C
63% here. The radicle and its branching root system form here. This is what Deno counts as germination.
- 3
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
A further 9%.
- 4
Warm moist stratification
Temperature: 70°F 21°C
The single true leaf forms only now. Germination is hypogeal.
Steps after step 2 run on after germination.
about 6 months from start to sowing. Then 84 days to germinate.
63% germination in 42–84 days.
Quicker than fresh seed at 70, and no better in the end. Start this lot cold instead.
This source doesn't state how long.
Protocol 6
DerivedN. C. Deno, 1993Difficulty High Rated by us, not by the source.
Start around June 19, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on June 18, 2026.
- 1
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
- 2
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
12% here.
- 3
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
A further 20%.
- 4
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
A further 18%.
- 5
Cold moist stratification
Temperature: 40°F 4°C
A last 2%.
Steps after step 3 run on after germination.
about 9 months from start to sowing. Germination time not stated; 21 days assumed.
20% germination.
Fresh seed started cold dribbles: 12, 20, 18 and 2 per cent over four cycles.
This source doesn't state how long.