Deno’s Garden

Penstemon flowersii

Genus Penstemon

Two sources report 5 treatments between them. All are shown.

Protocol 1

DerivedN. C. Deno, 1998

Difficulty Moderate Rated by us, not by the source.

Start around November 10, 2026 for a May 3 last frost.

  1. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  2. Warm moist stratification

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

    2/12 germinated in this phase.

Steps after step 1 run on after germination.

about 3 months from start to sowing. Then 56 days to germinate.

64% germination in 35–56 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. flowersii germ. 70D-40(2/2 iri 6th w) and 40(7/11 in 5-8 w)-70D(2/12 on 3rd d). Seeds DS 1 y germ. 40(3/19 in 7-11 w)-70D(2/19 on 3rd d) and seeds DS 2 y germ. 40(3/14 in 8-11 w) and 70D(none).
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 High Rated by us, not by the source.

Start around October 21, 2026 for a May 3 last frost. Too late for spring 2027 — that needed starting on October 20, 2025.

  1. Dry storage

    Duration: 365 daysTemperature: 70°F 21°C

  2. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  3. Warm moist stratification

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

    2/19 germinated in this phase.

Steps after step 2 run on after germination.

about 15 months from start to sowing. Then 77 days to germinate.

16% germination in 49–77 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. flowersii germ. 70D-40(2/2 iri 6th w) and 40(7/11 in 5-8 w)-70D(2/12 on 3rd d). Seeds DS 1 y germ. 40(3/19 in 7-11 w)-70D(2/19 on 3rd d) and seeds DS 2 y germ. 40(3/14 in 8-11 w) and 70D(none).
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 August 27, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on August 26, 2026.

  1. Warm moist stratification

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

  2. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

about 6 months from start to sowing. Then 42 days to germinate.

100% germination in 42 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. flowersii germ. 70D-40(2/2 iri 6th w) and 40(7/11 in 5-8 w)-70D(2/12 on 3rd d). Seeds DS 1 y germ. 40(3/19 in 7-11 w)-70D(2/19 on 3rd d) and seeds DS 2 y germ. 40(3/14 in 8-11 w) and 70D(none).
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 High Rated by us, not by the source.

Start around January 19, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on January 18, 2026.

  1. Dry storage

    Duration: 365 daysTemperature: 70°F 21°C

  2. Cold moist stratification

    Temperature: 40°F 4°C

about 12 months from start to sowing. Then 77 days to germinate.

21% germination in 56–77 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. flowersii germ. 70D-40(2/2 iri 6th w) and 40(7/11 in 5-8 w)-70D(2/12 on 3rd d). Seeds DS 1 y germ. 40(3/19 in 7-11 w)-70D(2/19 on 3rd d) and seeds DS 2 y germ. 40(3/14 in 8-11 w) and 70D(none).
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, 1993

Difficulty Low Rated 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

No stated waiting before sowing. Then 84 days to germinate.

100% germination in 42–84 days.

This source doesn't state how long.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Penstemon p. 187Public domain
Show the original text
Penstemon (Scrophulariaceae). Four types of germination were observed. Most Rocky Mountain species of a perennial nature germ. largely at 40 and often sowing at 70 was fatal or near fatal. A second group are short lived species that can flower the first year from seed typified by P. flowersii germ. 7.0(4%) and 40(100% in 6-12 w).
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Penstemon p. 187. 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.