Deno’s GardenMy Garden

Penstemon flowersii

Flowers' Beardtongue

Family PlantaginaceaeGenus Penstemon

A small clump of thick blue-green strap leaves with pale edges, low on cracked bare ground among dead gray stems.
The whole plantAndrey Zharkikh from Salt Lake City, USACC BY 2.0

About the plant

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

Habit
perennialPlants of the World Online
Habit
Perennial, Forb/herbPLANTS Database
Native range
UtahGBIF 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; GBIF Backbone Taxonomy — Global Biodiversity Information Facility.

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

Protocol 1

DerivedN. C. Deno, 1998

Difficulty Moderate Rated by us, not by the source.

Start around November 24, 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

about 3 months from start to step 2. Germination happens during step 2, in 42 days.

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 2

DerivedN. C. Deno, 1998

Difficulty Moderate Rated by us, not by the source.

Start around February 8, 2027 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.

Germination happens during step 1, in 56 days.

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 3

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 step 2. Germination happens during step 2, in 77 days.

21% germination in 56–77 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 4

DerivedN. C. Deno, 1998

Difficulty High Rated by us, not by the source.

Start around January 18, 2027 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.

Germination happens during step 1, in 77 days.

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 5

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

    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 12 months from start to step 2. Germination happens during step 2, in 77 days.

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 6

DerivedN. C. Deno, 1996

  1. Sow and cover

    Temperature: 70°F 21°C Light: dark

No stated waiting before sowing.

0% germination.

Nothing germinated at 70.

Seed Germination Theory and Practice, 1st Supplement — N. C. Deno, 1996 · 1st Supplement, Penstemon p. 64Public domain
Show the original text
Penstemon (Scrophulariaceae). P. flowersii germ. 40(7/12 in 5-10 w)-70D(2/12 on 2nd d), and none in 70D-40 or OS.
Seed Germination Theory and Practice, 1st Supplement, 1st Supplement, Penstemon p. 64. Quoted exactly. Every value on this card comes from this record; the step names come from a fixed list.

Protocol 7

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

Germination happens during step 1, in 84 days.

100% germination in 42–84 days.

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.

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

Add to My Garden

View species page