About the plant
What it is and where it grows — not part of any germination protocol.
Safety
- Toxicity
- Medium severity. Flowers, Leaves, Roots, Stems.
The plant
- Note
- Deno worked with garden hybrids rather than a named species, so these results are genus-level.
Toxicity is noted only where a source states it. No note here is not a finding of safety.
Sources: Seed Germination Theory and Practice, 2nd ed. — N. C. Deno; Extension Gardener Plant Toolbox — NC State Extension.
This source reports 7 treatments. All are shown.
Protocol 1
DerivedN. C. Deno, 1993Difficulty Moderate Rated by us, not by the source.
Start around December 14, 2026 for a May 3 last frost. Too late for spring 2027 — that needed starting on December 13, 2025.
- 1
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
Deno names the three-month cycle at 40 in this entry.
- 2
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
- 3
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
Only 5% here.
- 4
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
- 5
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
90%, in 2-4 weeks. Leave the seedlings at 40 for the full three months, or the leaf comes up weak when they move to 70.
about 15 months from start to sowing. Then 28 days to germinate.
90% germination in 14–28 days.
A second lot of fresh seed: almost nothing until the third cold period, then 90%.
Protocol 2
DerivedN. C. Deno, 1993Difficulty Moderate Rated by us, not by the source.
Start around December 21, 2026 for a May 3 last frost. Too late for spring 2027 — that needed starting on December 20, 2025.
- 1
Dry storage
Duration: 180 days · Temperature: 40°F 4°C
- 2
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
11% here. Deno names the three-month cycle at 40 in this entry.
- 3
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
- 4
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
A further 89%. Leave the seedlings at 40 for the full three months, or the leaf comes up weak when they move to 70.
about 15 months from start to sowing. Germination time not stated; 21 days assumed.
89% germination.
Six months dry at 40 barely hurts the cold-first route: 11% then 89%.
Protocol 3
DerivedN. C. Deno, 1993Difficulty Low Rated by us, not by the source.
Start around September 3, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on September 2, 2026.
- 1
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
Deno names the three-month cycle at 40 in this entry.
- 2
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
Leave the seedlings at 40 for the full three months, or the leaf comes up weak when they move to 70.
about 6 months from start to sowing. Then 35 days to germinate.
75% germination in 14–35 days.
Deno's seed was garden hybrids. The shortest route, and 75% of it.
Protocol 4
DerivedN. C. Deno, 1993Difficulty Moderate Rated by us, not by the source.
Start around December 21, 2026 for a May 3 last frost. Too late for spring 2027 — that needed starting on December 20, 2025.
- 1
Dry storage
Duration: 180 days · Temperature: 70°F 21°C
- 2
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
14% here. Deno names the three-month cycle at 40 in this entry.
- 3
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
- 4
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
A further 65%. Leave the seedlings at 40 for the full three months, or the leaf comes up weak when they move to 70.
about 15 months from start to sowing. Germination time not stated; 21 days assumed.
65% germination.
Stored at 70 rather than 40 and the seed deteriorates faster: 65% against 89%.
Protocol 5
DerivedN. C. Deno, 1993Difficulty Moderate Rated by us, not by the source.
Start around October 27, 2026 for a May 3 last frost.
- 1
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
60% here, in 6-10 weeks. Deno names the three-month cycle at 40 in this entry.
- 2
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
- 3
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
- 4
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
- 5
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
A further 20%. Leave the seedlings at 40 for the full three months, or the leaf comes up weak when they move to 70.
Steps after step 1 run on after germination.
about 3 months from start to sowing. Then 70 days to germinate.
60% germination in 42–70 days.
Deno's seed was garden hybrids. 60% in the first cold period, 20% more two cycles on.
Protocol 6
DerivedN. C. Deno, 1993Difficulty High Rated by us, not by the source.
Start around March 21, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on March 20, 2026.
- 1
Dry storage
Duration: 180 days · Temperature: 40°F 4°C
- 2
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
Deno names the three-month cycle at 40 in this entry.
- 3
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
Leave the seedlings at 40 for the full three months, or the leaf comes up weak when they move to 70.
about 12 months from start to sowing. Germination time not stated; 21 days assumed.
20% germination.
Dry storage wrecks the warm-first route: 20%, against 75% from fresh seed.
Protocol 7
DerivedN. C. Deno, 1993Difficulty High Rated by us, not by the source.
- 1
Dry storage
Duration: 180 days · Temperature: 70°F 21°C
- 2
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
Deno names the three-month cycle at 40 in this entry.
- 3
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
Anywhere from nothing to 20%. Leave the seedlings at 40 for the full three months, or the leaf comes up weak when they move to 70.
about 12 months from start to sowing. Germination time not stated; 21 days assumed.
Deno gives 0-20% here -- too variable to state. The worst of Deno’s seven routes.