Asclepias syriaca Genus Asclepias
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About the plant What it is and where it grows — not part of any germination protocol.
The plant
Habit Herbaceous Perennial, Wildflower Extension Gardener Plant Toolbox
Height 3-5 ft 0.9-1.5 m Extension Gardener Plant Toolbox
Spread 0.7-1 ft 20-30 cm Extension Gardener Plant Toolbox
Flower Green, Pink, Purple/Lavender, White Extension Gardener Plant Toolbox
Blooms Summer Extension Gardener Plant Toolbox
Hardiness zones 3-9 Extension Gardener Plant Toolbox Growing conditions
Sun Full sun Extension Gardener Plant Toolbox
Soil Clay, Loam (Silt), Sand, Shallow Rocky Extension Gardener Plant Toolbox
Moisture Good Drainage, Occasionally Dry Extension Gardener Plant Toolbox Toxicity is noted only where a source states it. No note here is not a finding of safety.
Source: Extension Gardener Plant Toolbox — NC State Extension.
This source reports 5 treatments. All are shown.
Protocol 1 N. C. Deno, 1993 Difficulty Low Rated by us, not by the source.
Start around March 18, 2027 for a May 3 last frost.
1 2 Sow and cover
Temperature: 70°F 21°C · Light: dark
No stated waiting before sowing. Then 18 days to germinate.
97% germination in 5–18 days.
Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Asclepias p. 103Public domain Show the original text Asclepias (Asclepiadaceae). The four species studied have wind born seed indicating that DS is tolerated. This was generally true; but some deterioration on DS was noted in A. syriacus germ. under three conditions. These were 70D if treated with GA-3, 70L if given a preliminary 3 m at 40, and outdoor treatment. 'Such a combination is unusual. The data were 70D GA-3(97% in 5-18 d) and 40-70L(47% in 1-3 w for fresh seed and 58% in 1-3 w for seed DS 6 m at 70). Outdoor treatment gave 3% in October and 84% in April for fresh seed placed outdoors in September and 70% in April for seed DS 6 m at 70 and placed outdoor March 1. All other treatments failed to give a single germination with fresh 'seed. However, the DS seed germ. 701L(21% in 3-10 d), 70D(18% in 12th w), and 40-70D(10%). It is as if the DS destroyed some of the inhibiting systems. The seedlings from the GA-3 treatement developed normal cotyledons and radicles. Seed Germination Theory and Practice, 2nd ed., Ch. 20, Asclepias p. 103. Quoted exactly. Every value on this card comes from this record, except the difficulty rating, which is ours; the step names come from a fixed list. Protocol 2 N. C. Deno, 1993 Difficulty Moderate Rated by us, not by the source.
Start around September 17, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on September 16, 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 · Light: light
about 6 months from start to sowing. Then 21 days to germinate.
47% germination in 7–21 days.
Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Asclepias p. 103Public domain Show the original text Asclepias (Asclepiadaceae). The four species studied have wind born seed indicating that DS is tolerated. This was generally true; but some deterioration on DS was noted in A. syriacus germ. under three conditions. These were 70D if treated with GA-3, 70L if given a preliminary 3 m at 40, and outdoor treatment. 'Such a combination is unusual. The data were 70D GA-3(97% in 5-18 d) and 40-70L(47% in 1-3 w for fresh seed and 58% in 1-3 w for seed DS 6 m at 70). Outdoor treatment gave 3% in October and 84% in April for fresh seed placed outdoors in September and 70% in April for seed DS 6 m at 70 and placed outdoor March 1. All other treatments failed to give a single germination with fresh 'seed. However, the DS seed germ. 701L(21% in 3-10 d), 70D(18% in 12th w), and 40-70D(10%). It is as if the DS destroyed some of the inhibiting systems. The seedlings from the GA-3 treatement developed normal cotyledons and radicles. Seed Germination Theory and Practice, 2nd ed., Ch. 20, Asclepias p. 103. Quoted exactly. Every value on this card comes from this record, except the difficulty rating, which is ours; the step names come from a fixed list. Protocol 3 N. C. Deno, 1993 Difficulty High 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 Sow and cover
Temperature: 70°F 21°C · Light: dark
about 6 months from start to sowing. Then 84 days to germinate.
18% germination in 84 days.
Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Asclepias p. 103Public domain Show the original text Asclepias (Asclepiadaceae). The four species studied have wind born seed indicating that DS is tolerated. This was generally true; but some deterioration on DS was noted in A. syriacus germ. under three conditions. These were 70D if treated with GA-3, 70L if given a preliminary 3 m at 40, and outdoor treatment. 'Such a combination is unusual. The data were 70D GA-3(97% in 5-18 d) and 40-70L(47% in 1-3 w for fresh seed and 58% in 1-3 w for seed DS 6 m at 70). Outdoor treatment gave 3% in October and 84% in April for fresh seed placed outdoors in September and 70% in April for seed DS 6 m at 70 and placed outdoor March 1. All other treatments failed to give a single germination with fresh 'seed. However, the DS seed germ. 701L(21% in 3-10 d), 70D(18% in 12th w), and 40-70D(10%). It is as if the DS destroyed some of the inhibiting systems. The seedlings from the GA-3 treatement developed normal cotyledons and radicles. Seed Germination Theory and Practice, 2nd ed., Ch. 20, Asclepias p. 103. Quoted exactly. Every value on this card comes from this record, except the difficulty rating, which is ours; the step names come from a fixed list. Protocol 4 N. C. Deno, 1993 Difficulty 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: 70°F 21°C
2 Cold moist stratification
Duration: 90 days · Temperature: 40°F 4°C
3 Warm moist stratification
Duration: 90 days · Temperature: 70°F 21°C · Light: dark
about 12 months from start to sowing. Germination time not stated; 21 days assumed.
10% germination.
Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Asclepias p. 103Public domain Show the original text Asclepias (Asclepiadaceae). The four species studied have wind born seed indicating that DS is tolerated. This was generally true; but some deterioration on DS was noted in A. syriacus germ. under three conditions. These were 70D if treated with GA-3, 70L if given a preliminary 3 m at 40, and outdoor treatment. 'Such a combination is unusual. The data were 70D GA-3(97% in 5-18 d) and 40-70L(47% in 1-3 w for fresh seed and 58% in 1-3 w for seed DS 6 m at 70). Outdoor treatment gave 3% in October and 84% in April for fresh seed placed outdoors in September and 70% in April for seed DS 6 m at 70 and placed outdoor March 1. All other treatments failed to give a single germination with fresh 'seed. However, the DS seed germ. 701L(21% in 3-10 d), 70D(18% in 12th w), and 40-70D(10%). It is as if the DS destroyed some of the inhibiting systems. The seedlings from the GA-3 treatement developed normal cotyledons and radicles. Seed Germination Theory and Practice, 2nd ed., Ch. 20, Asclepias p. 103. Quoted exactly. Every value on this card comes from this record, except the difficulty rating, which is ours; the step names come from a fixed list. Protocol 5 N. C. Deno, 1993 Difficulty Very high Rated by us, not by the source.
Sow around September 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 September 2026.
1 Sow outdoors and leave it
Sown outdoors in September; up in October.
No stated waiting before sowing. Then 30 days to germinate.
3% germination in 30 days.
This source doesn't state how long.
Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Asclepias p. 103Public domain Show the original text Asclepias (Asclepiadaceae). The four species studied have wind born seed indicating that DS is tolerated. This was generally true; but some deterioration on DS was noted in A. syriacus germ. under three conditions. These were 70D if treated with GA-3, 70L if given a preliminary 3 m at 40, and outdoor treatment. 'Such a combination is unusual. The data were 70D GA-3(97% in 5-18 d) and 40-70L(47% in 1-3 w for fresh seed and 58% in 1-3 w for seed DS 6 m at 70). Outdoor treatment gave 3% in October and 84% in April for fresh seed placed outdoors in September and 70% in April for seed DS 6 m at 70 and placed outdoor March 1. All other treatments failed to give a single germination with fresh 'seed. However, the DS seed germ. 701L(21% in 3-10 d), 70D(18% in 12th w), and 40-70D(10%). It is as if the DS destroyed some of the inhibiting systems. The seedlings from the GA-3 treatement developed normal cotyledons and radicles. Seed Germination Theory and Practice, 2nd ed., Ch. 20, Asclepias p. 103. Quoted exactly. Every value on this card comes from this record, except the difficulty rating, which is ours; the step names come from a fixed list. How each step is done , in Deno’s words, and what Verified and Derived mean.
