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Penstemon heterophyllus

Bunchleaf Penstemon

Family PlantaginaceaeGenus Penstemon

A vivid blue-violet flower opening wide, its upper lip arching over dark anthers and a white staminode.
FlowerStickpenPublic domain

About the plant

What it is and where it grows — not part of any germination protocol.

Habit
subshrubPlants of the World Online
Habit
Perennial, Forb/herb, SubshrubPLANTS Database
Flower
Blue, purple, magentaWikipedia
Native range
CaliforniaGBIF Backbone Taxonomy

Toxicity is noted only where a source states it. No note here is not a finding of safety.

Sources: Plants of the World Online — Royal Botanic Gardens, Kew; PLANTS Database — USDA NRCS; Wikipedia — Wikipedia contributors; GBIF Backbone Taxonomy — Global Biodiversity Information Facility.

Worth knowing

  • Endemic to California, it is grown by nurseries for Mediterranean-climate and other low-water gardens, in cultivars such as 'Electric Blue', with intense blue flowers. Wikipedia: Penstemon heterophyllus

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 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 step 2. Germination happens during step 2, in 56 days.

100% germination in 28–56 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. 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 January 25, 2027 for a May 3 last frost.

  1. Cold moist stratification

    Temperature: 40°F 4°C Light: either

Germination happens during step 1, in 70 days.

95% germination in 56–70 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 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 March 15, 2027 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.

Germination happens during step 1, in 21 days.

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 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.

Protocol 7

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.

How each step is done, in Deno’s words, and what Verified and Derived mean.

Germination trials

Readers’ own records of sowing this species, published after review. Share your trial · All trials

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