Deno’s GardenMy Garden

Penstemon whippleanus

Dusky Beardtongue · Dusky Penstemon · Whipple's Beardtongue · Whipple's Penstemon

Family PlantaginaceaeGenus Penstemon

Whorls of dark wine-purple hooded flowers, some almost black, hanging in tiers around an upright stem in grass.
FlowerScott LoarieCC BY 2.0

About the plant

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

The plant

Habit
perennialPlants of the World Online
Habit
Perennial, Forb/herb, SubshrubPLANTS Database
Height
3.0 ft90 cmPLANTS Database
Flower
PurplePLANTS Database
Blooms
Late SummerPLANTS Database
Native range
Native to the lower 48 statesPLANTS Database

Growing conditions

Sun
Shade tolerance: MediumPLANTS Database
Soil
Adapted to coarse, medium textured soilsPLANTS Database
Soil pH
7.0-8.0PLANTS Database
Moisture
Moisture use: MediumPLANTS Database
Watering
Drought tolerance: MediumPLANTS Database

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.

Worth knowing

  • Asa Gray named it for Lt. Amiel Weeks Whipple, leader of one of the two southern Pacific Railroad Surveys. Also called dusky penstemon, it is noted for its large deep purple-red flowers and for growing high in the mountains. Wikipedia: Penstemon whippleanus

This source reports two treatments. Both are shown.

Protocol 1

DerivedN. C. Deno, 1993

Difficulty High Rated by us, not by the source.

Start around March 6, 2027 for a May 3 last frost.

  1. Sow and cover

    Temperature: 70°F 21°C

No stated waiting before sowing. Then 30 days to germinate.

20% germination in 4–30 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.whippleanus germ. 70(20% in 4-30 d) and 40-70(20% in 4-6 d).
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.

Protocol 2

DerivedN. C. Deno, 1993

Difficulty High Rated by us, not by the source.

Start around December 30, 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

about 3 months from start to step 2. Germination happens during step 2, in 6 days.

20% germination in 4–6 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.whippleanus germ. 70(20% in 4-30 d) and 40-70(20% in 4-6 d).
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