Also published as Jeffersonia dubia. You are in the right place.
About the plant
What it is and where it grows — not part of any germination protocol.
Note
Germination is hypogeal: a four-inch radicle first, the single leaf a week or two later.
Toxicity is noted only where a source states it. No note here is not a finding of safety.
Source: Seed Germination Theory and Practice, 2nd ed. — N. C. Deno.
This source reports 4 treatments. All are shown.
Protocol 1
DerivedN. C. Deno, 1993
Difficulty LowRated by us, not by the source.
Sow around June 2027 — a date the source gives, not one counted back from a May 3 last frost. Too late for spring 2027 — that needed starting on June 2026.
1
Sow outdoors and leave it
Sown outdoors in June; up the following March.
No stated waiting before sowing. Then 270 days to germinate.
48% germination in 270 days.
Sowing outdoors beat two years of cycling. The prominent aril need not be removed.
This source doesn't state how long.
Protocol 2
DerivedN. C. Deno, 1993
Difficulty Very highRated by us, not by the source.
Start around June 24, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on June 23, 2025.
1
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
Deno gives no cycle lengths here; three months is his standard cycle.
2
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
4% in the first cold period.
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 2%.
5
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
A further 4%.
6
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
A further 14%.
7
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
24% -- the largest flush.
8
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
A further 6%.
9
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
10
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
11
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
A last 2%.
Steps after step 7 run on after germination.
about 1.5 years from start to sowing. Germination time not stated; 21 days assumed.
24% germination.
56% in all, across eleven cycles -- the better part of three years for what June sowing gives in nine months.
Protocol 3
DerivedN. C. Deno, 1993
Difficulty Very highRated 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
Deno gives no cycle lengths here; three months is his standard cycle.
2
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
3
Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
8%, and nothing in the cycle that followed.
4
Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C
Steps after step 3 run on after germination.
about 9 months from start to sowing. Germination time not stated; 21 days assumed.
8% germination.
Eight per cent in the second cold period, and nothing after it.
Protocol 4
DerivedN. C. Deno, 1993
1
Dry storage
Duration: 180 days · Temperature: 70°F 21°C
2
Sow and cover
None survived the dry storage.
about 6 months from start to sowing.
0% germination.
Dry storage is fatal. Six months at 40 left a few per cent alive; six months at 70 left none.