Deno’s GardenMy Garden

Polemonium pulcherrimum

Beautiful Jacob's-ladder · Pretty Jacob's-ladder · Short Jacob's-ladder · Jacob's-ladder

Family PolemoniaceaeGenus Polemonium

Two violet flowers with orange-yellow eyes and dark veining, their white stamens curving out over the petals.
FlowerWalter Siegmund (talk)CC BY-SA 3.0

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
Flower
Deep blue, pale blueWikipedia
Native range
Alaska, Canada, lower 48 statesPLANTS 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; Wikipedia — Wikipedia contributors.

Worth knowing

This source reports 7 treatments. All are shown.

Protocol 1

DerivedN. C. Deno, 1993

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: light

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

56% germination in 14 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Polemonium p. 195Public domain
Show the original text
Polemonium (Polemoniaceae). The following germ: in 2-5 w at 70: P. pulcherrimum v.calycinum gerni. 70L(56% in 2nd w), 70D(17% in 2nd w), and 40(32% in 2-7 w).
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Polemonium p. 195. 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 Moderate Rated by us, not by the source.

Start around September 3, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on September 2, 2026.

  1. Dry storage

    Duration: 180 daysTemperature: 70°F 21°C

  2. Cold moist stratification

    Temperature: 40°F 4°C

about 6 months from start to step 2. Germination happens during step 2, in 35 days.

50% germination in 21–35 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Polemonium p. 195Public domain
Show the original text
Polemonium (Polemoniaceae). The following germ: in 2-5 w at 70: P. delicatum self sows in sand beds here and is remarkably resistant to drought. Seeds DS 6 m at 70 germ. 40(50% in 3-5 w) and 70(40% in 1-3 w). Fresh seed germ. 40(48% in 2-10 w) and 70-40(10%)-70(8%)-40...
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Polemonium p. 195. 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, 1993

Difficulty Moderate 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

Germination happens during step 1, in 70 days.

48% germination in 14–70 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Polemonium p. 195Public domain
Show the original text
Polemonium (Polemoniaceae). The following germ: in 2-5 w at 70: P. delicatum self sows in sand beds here and is remarkably resistant to drought. Seeds DS 6 m at 70 germ. 40(50% in 3-5 w) and 70(40% in 1-3 w). Fresh seed germ. 40(48% in 2-10 w) and 70-40(10%)-70(8%)-40...
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Polemonium p. 195. 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, 1993

Difficulty Moderate Rated by us, not by the source.

Start around September 17, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on September 16, 2026.

  1. Dry storage

    Duration: 180 daysTemperature: 70°F 21°C

  2. Sow and cover

    Temperature: 70°F 21°C

about 6 months from start to sowing. Then 21 days to germinate.

40% germination in 7–21 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Polemonium p. 195Public domain
Show the original text
Polemonium (Polemoniaceae). The following germ: in 2-5 w at 70: P. delicatum self sows in sand beds here and is remarkably resistant to drought. Seeds DS 6 m at 70 germ. 40(50% in 3-5 w) and 70(40% in 1-3 w). Fresh seed germ. 40(48% in 2-10 w) and 70-40(10%)-70(8%)-40...
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Polemonium p. 195. 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 Moderate Rated by us, not by the source.

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

  1. Cold moist stratification

    Temperature: 40°F 4°C

Germination happens during step 1, in 49 days.

32% germination in 14–49 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Polemonium p. 195Public domain
Show the original text
Polemonium (Polemoniaceae). The following germ: in 2-5 w at 70: P. pulcherrimum v.calycinum gerni. 70L(56% in 2nd w), 70D(17% in 2nd w), and 40(32% in 2-7 w).
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Polemonium p. 195. 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, 1993

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 Light: dark

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

17% germination in 14 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Polemonium p. 195Public domain
Show the original text
Polemonium (Polemoniaceae). The following germ: in 2-5 w at 70: P. pulcherrimum v.calycinum gerni. 70L(56% in 2nd w), 70D(17% in 2nd w), and 40(32% in 2-7 w).
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Polemonium p. 195. 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, 1993

Difficulty High Rated by us, not by the source.

Start around December 15, 2026 for a May 3 last frost.

  1. Warm moist stratification

    Duration: 90 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

    8 germinated in this phase.

  4. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

Steps after step 2 run on after germination.

about 3 months from start to step 2. Germination happens during step 2; time not stated, 21 days assumed.

10% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Polemonium p. 195Public domain
Show the original text
Polemonium (Polemoniaceae). The following germ: in 2-5 w at 70: P. delicatum self sows in sand beds here and is remarkably resistant to drought. Seeds DS 6 m at 70 germ. 40(50% in 3-5 w) and 70(40% in 1-3 w). Fresh seed germ. 40(48% in 2-10 w) and 70-40(10%)-70(8%)-40...
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Polemonium p. 195. 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