Deno’s Garden

Penstemon heterophyllus

Genus Penstemon

Two sources report 7 treatments between them. All are shown.

Protocol 1

DerivedN. C. Deno, 1998

Difficulty Low Rated by us, not by the source.

Start around January 25, 2027 for a May 3 last frost.

  1. Cold moist stratification

    Temperature: 40°F 4°C Light: either

No stated waiting before sowing. Then 70 days to germinate.

95% germination in 56–70 days.

This source doesn't state how long.

Seed Germination Theory and Practice, 2nd Supplement — N. C. Deno, 1998 · 2nd Supplement, Penstemon p. 52Public domain
Show the original text
Penstemon (Scrophulariaceae). Some of the following data are updates on species reported in the 1st Suppl. As noted in the 2nd Ed. and 1st Suppl., 'there is a wide range of germination behaviors in this genus ranging from requirements for light, oscillating temperatures, low temperatures, and GA-3. P. heterophyllus germ. 70D(65% in 1-3 w)-40(15% in 4-12 w) and 40(95% in 8-10 w). Light had no effect. Seeds DS 1 y germ. 70D(67% in 1-3 w). Seeds DS 2 y germ. 40(5/5 in 4-8 w) .and 70D(1/9) which shows virtually no dying.
Seed Germination Theory and Practice, 2nd Supplement, 2nd Supplement, Penstemon p. 52. 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

DerivedN. C. Deno, 1998

Difficulty Low Rated by us, not by the source.

Start around February 9, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on February 8, 2025.

  1. Dry storage

    Duration: 730 daysTemperature: 70°F 21°C

  2. Cold moist stratification

    Temperature: 40°F 4°C Light: either

about 2 years from start to sowing. Then 56 days to germinate.

100% germination in 28–56 days.

This source doesn't state how long.

Seed Germination Theory and Practice, 2nd Supplement — N. C. Deno, 1998 · 2nd Supplement, Penstemon p. 52Public domain
Show the original text
Penstemon (Scrophulariaceae). Some of the following data are updates on species reported in the 1st Suppl. As noted in the 2nd Ed. and 1st Suppl., 'there is a wide range of germination behaviors in this genus ranging from requirements for light, oscillating temperatures, low temperatures, and GA-3. P. heterophyllus germ. 70D(65% in 1-3 w)-40(15% in 4-12 w) and 40(95% in 8-10 w). Light had no effect. Seeds DS 1 y germ. 70D(67% in 1-3 w). Seeds DS 2 y germ. 40(5/5 in 4-8 w) .and 70D(1/9) which shows virtually no dying.
Seed Germination Theory and Practice, 2nd Supplement, 2nd Supplement, Penstemon p. 52. 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

DerivedN. C. Deno, 1998

Difficulty Moderate Rated by us, not by the source.

Start around March 16, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on March 15, 2026.

  1. Dry storage

    Duration: 365 daysTemperature: 70°F 21°C

  2. Sow and cover

    Temperature: 70°F 21°C Light: dark

about 12 months from start to sowing. Then 21 days to germinate.

67% germination in 7–21 days.

Seed Germination Theory and Practice, 2nd Supplement — N. C. Deno, 1998 · 2nd Supplement, Penstemon p. 52Public domain
Show the original text
Penstemon (Scrophulariaceae). Some of the following data are updates on species reported in the 1st Suppl. As noted in the 2nd Ed. and 1st Suppl., 'there is a wide range of germination behaviors in this genus ranging from requirements for light, oscillating temperatures, low temperatures, and GA-3. P. heterophyllus germ. 70D(65% in 1-3 w)-40(15% in 4-12 w) and 40(95% in 8-10 w). Light had no effect. Seeds DS 1 y germ. 70D(67% in 1-3 w). Seeds DS 2 y germ. 40(5/5 in 4-8 w) .and 70D(1/9) which shows virtually no dying.
Seed Germination Theory and Practice, 2nd Supplement, 2nd Supplement, Penstemon p. 52. 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

DerivedN. C. Deno, 1998

Difficulty Moderate Rated by us, not by the source.

Start around December 15, 2026 for a May 3 last frost.

  1. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C Light: dark

  2. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C Light: either

    15 germinated in this phase.

Steps after step 1 run on after germination.

about 3 months from start to sowing. Then 21 days to germinate.

65% germination in 7–21 days.

Seed Germination Theory and Practice, 2nd Supplement — N. C. Deno, 1998 · 2nd Supplement, Penstemon p. 52Public domain
Show the original text
Penstemon (Scrophulariaceae). Some of the following data are updates on species reported in the 1st Suppl. As noted in the 2nd Ed. and 1st Suppl., 'there is a wide range of germination behaviors in this genus ranging from requirements for light, oscillating temperatures, low temperatures, and GA-3. P. heterophyllus germ. 70D(65% in 1-3 w)-40(15% in 4-12 w) and 40(95% in 8-10 w). Light had no effect. Seeds DS 1 y germ. 70D(67% in 1-3 w). Seeds DS 2 y germ. 40(5/5 in 4-8 w) .and 70D(1/9) which shows virtually no dying.
Seed Germination Theory and Practice, 2nd Supplement, 2nd Supplement, Penstemon p. 52. 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

DerivedN. C. Deno, 1998

Difficulty High Rated by us, not by the source.

Start around March 16, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on March 15, 2025.

  1. Dry storage

    Duration: 730 daysTemperature: 70°F 21°C

  2. Sow and cover

    Temperature: 70°F 21°C Light: dark

about 2 years from start to sowing. Germination time not stated; 21 days assumed.

11% germination.

Seed Germination Theory and Practice, 2nd Supplement — N. C. Deno, 1998 · 2nd Supplement, Penstemon p. 52Public domain
Show the original text
Penstemon (Scrophulariaceae). Some of the following data are updates on species reported in the 1st Suppl. As noted in the 2nd Ed. and 1st Suppl., 'there is a wide range of germination behaviors in this genus ranging from requirements for light, oscillating temperatures, low temperatures, and GA-3. P. heterophyllus germ. 70D(65% in 1-3 w)-40(15% in 4-12 w) and 40(95% in 8-10 w). Light had no effect. Seeds DS 1 y germ. 70D(67% in 1-3 w). Seeds DS 2 y germ. 40(5/5 in 4-8 w) .and 70D(1/9) which shows virtually no dying.
Seed Germination Theory and Practice, 2nd Supplement, 2nd Supplement, Penstemon p. 52. 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 6

DerivedN. C. Deno, 1996

Difficulty Moderate Rated by us, not by the source.

Start around March 22, 2027 for a May 3 last frost.

  1. Sow and cover

    Temperature: 70°F 21°C Light: dark

No stated waiting before sowing. Then 14 days to germinate.

66% germination in 14 days.

Seed Germination Theory and Practice, 1st Supplement — N. C. Deno, 1996 · 1st Supplement, Penstemon p. 64Public domain
Show the original text
Penstemon (Scrophulariaceae). P. heterophyllus germ. 70D(66% in 2nd w), 70L(67% in 1-3 w), and 40(none).
Seed Germination Theory and Practice, 1st Supplement, 1st Supplement, Penstemon p. 64. 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 7

DerivedN. C. Deno, 1996

Difficulty Moderate Rated by us, not by the source.

Start around March 15, 2027 for a May 3 last frost.

  1. Sow and cover

    Temperature: 70°F 21°C Light: light

No stated waiting before sowing. Then 21 days to germinate.

67% germination in 7–21 days.

Seed Germination Theory and Practice, 1st Supplement — N. C. Deno, 1996 · 1st Supplement, Penstemon p. 64Public domain
Show the original text
Penstemon (Scrophulariaceae). P. heterophyllus germ. 70D(66% in 2nd w), 70L(67% in 1-3 w), and 40(none).
Seed Germination Theory and Practice, 1st Supplement, 1st Supplement, Penstemon p. 64. 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.