What it is and where it grows — not part of any germination protocol.
The plant
Habit
Herbaceous perennialPlant Finder
Habit
Biennial, Forb/herbPLANTS Database
Height
2-4 ftPlant Finder
Spread
2-3 ftPlant Finder
Flower
Showy, fragrant; white to lavenderPlant Finder
Blooms
June to AugustPlant Finder
Native range
North AmericaGBIF Backbone Taxonomy
Native range
Europe to Central AsiaPlant Finder
Hardiness zones
5-9Plant Finder
Note
Deno tested a 60 cm and a 180 cm form separately; only the tall one germinates cold.Seed Germination Theory and Practice, 2nd ed.
Note
Fragrant leaves. Tolerates deer, drought and shallow rocky soil.Plant Finder
Growing conditions
Sun
Full sun
Soil
Average, medium moisture, 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; GBIF Backbone Taxonomy — Global Biodiversity Information Facility; Seed Germination Theory and Practice, 2nd ed. — N. C. Deno.
This source reports 8 treatments. All are shown.
Protocol 1
DerivedN. C. Deno, 1993
Difficulty LowRated by us, not by the source.
Start around March 30, 2027 for a May 3 last frost.
1
Sow on the surface — do not cover
Temperature: 70°F 21°C · Light: light
No stated waiting before sowing. Then 6 days to germinate.
61% germination in 2–6 days.
The best of eight. Deno's 180 cm form.
Protocol 2
DerivedN. C. Deno, 1993
Difficulty LowRated by us, not by the source.
Start around March 24, 2027 for a May 3 last frost.
1
Sow on the surface — do not cover
Temperature: 70°F 21°C · Light: light
No stated waiting before sowing. Then 12 days to germinate.
46% germination in 2–12 days.
Light is worth fifteen points on this form. Deno's 60 cm form.
Protocol 3
DerivedN. C. Deno, 1993
Difficulty ModerateRated 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 · Light: dark
No stated waiting before sowing. Then 7 days to germinate.
43% germination in 2–7 days.
Dark costs the tall form eighteen points. Deno's 180 cm form.
Protocol 4
DerivedN. C. Deno, 1993
Difficulty ModerateRated by us, not by the source.
Start around January 11, 2027 for a May 3 last frost.
1
Cold moist stratification
Temperature: 40°F 4°C
41%, over 7-12 weeks.
2
Warm moist stratification
Temperature: 70°F 21°C
No stated waiting before sowing. Then 84 days to germinate.
41% germination in 49–84 days.
The tall form germinates cold; the short form barely does at all. Deno's 180 cm form.
This source doesn't state how long.
Protocol 5
DerivedN. C. Deno, 1993
Difficulty ModerateRated by us, not by the source.
Start around March 15, 2027 for a May 3 last frost.
1
Sow outdoors and leave it
No stated waiting before sowing. Germination time not stated; 21 days assumed.
40% germination.
40% outdoors. Deno's 60 cm form.
This source doesn't state how long.
Protocol 6
DerivedN. C. Deno, 1993
Difficulty ModerateRated by us, not by the source.
Start around March 24, 2027 for a May 3 last frost.
1
Sow and cover
Temperature: 70°F 21°C · Light: dark
No stated waiting before sowing. Then 12 days to germinate.
31% germination in 2–12 days.
Dark costs the short form fifteen points. Deno's 60 cm form.
Protocol 7
DerivedN. C. Deno, 1993
Difficulty ModerateRated by us, not by the source.
Start around March 15, 2027 for a May 3 last frost.
1
Sow outdoors and leave it
No stated waiting before sowing. Germination time not stated; 21 days assumed.
27% germination.
27% outdoors, against 40% for the short form. Deno's 180 cm form.
This source doesn't state how long.
Protocol 8
DerivedN. C. Deno, 1993
Difficulty Very highRated 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
1% here.
2
Warm moist stratification
Temperature: 70°F 21°C
A further 2%.
No stated waiting before sowing. Germination time not stated; 21 days assumed.
2% germination.
1% in the cold and 2% after it. The short form will not take a cold start. Deno's 60 cm form.