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Penstemon cobaea

Prairie Penstemon · Wild Foxglove · Cobaea Beardtongue

Family PlantaginaceaeGenus Penstemon

Large pale pink bells with darker veining and open throats, crowded up a leafy stem in front of a barbed-wire fence.
FlowerClarence A. Rechenthin. Courtesy of USDA NRCS Texas State Office.Public domain

About the plant

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

The plant

Habit
Herbaceous Perennial, WildflowerExtension Gardener Plant Toolbox
Habit
perennialPlants of the World Online
Height
1-2 ft30-60 cmExtension Gardener Plant Toolbox
Spread
1-1.5 ft30-45 cmExtension Gardener Plant Toolbox
Flower
Pink, Purple/Lavender, WhiteExtension Gardener Plant Toolbox
Blooms
SpringExtension Gardener Plant Toolbox
Native range
Native to the lower 48 statesPLANTS Database
Hardiness zones
5-8Extension Gardener Plant Toolbox

Growing conditions

Sun
Full sun; Partial ShadeExtension Gardener Plant Toolbox
Soil
Loam (Silt), Sand, Shallow RockyExtension Gardener Plant Toolbox
Soil pH
Acid (<6.0)Extension Gardener Plant Toolbox
Moisture
Good Drainage, Occasionally DryExtension Gardener Plant Toolbox

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

Sources: Extension Gardener Plant Toolbox — NC State Extension; Plants of the World Online — Royal Botanic Gardens, Kew; PLANTS Database — USDA NRCS.

Worth knowing

This source reports two treatments. Both are shown.

Protocol 1

DerivedN. C. Deno, 1998

Difficulty Low Rated by us, not by the source.

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

  1. Gibberellic acid soak

  2. Sow and cover

    Temperature: 70°F 21°C

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

90% 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. cobaea germ. 70 GA-3(9/10 in 1-3 w) and 70(1/10 in 2nd w) (KR). This is out of accord with earlier data which showed germination in 2-6 w at 70 (2nd Ed.).
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 March 22, 2027 for a May 3 last frost.

  1. Sow and cover

    Temperature: 70°F 21°C

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

10% germination in 14 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. cobaea germ. 70 GA-3(9/10 in 1-3 w) and 70(1/10 in 2nd w) (KR). This is out of accord with earlier data which showed germination in 2-6 w at 70 (2nd Ed.).
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.

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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