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Delphinium geyeri

Geyer's Larkspur · Plains Larkspur · Poisonweed

Family RanunculaceaeGenus Delphinium

Royal blue flowers with a white center and five spreading petals, crowded along a stem, each backed by a long spur.
FloweraspidoscelisCC0

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
Bright blueFlora of North America
Native range
Colorado, Nebraska, Utah, WyomingGBIF 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; Flora of North America — Flora of North America Editorial Committee; GBIF Backbone Taxonomy — Global Biodiversity Information Facility.

Worth knowing

  • Notorious for killing cattle that graze it in spring: it is most poisonous before it flowers. Ranchers call it poisonweed. Wikipedia: Delphinium geyeri

This source reports two treatments. Both are shown.

Protocol 1

DerivedN. C. Deno, 1993

Difficulty Very high 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. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  2. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

  3. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

about 6 months from start to step 3. Germination happens during step 3; time not stated, 21 days assumed.

5% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Delphinium p. 130Public domain
Show the original text
Delphinium (Ranunculaceae). . This genus is composed of a group of medium heigth monocarpic species typified by D. geyeri germ. 57% at the end of March from outdoor sowing in late fall. Germination dropped to 5% when sown at 70 or 40 as shown by 70-40(5%)-70 and 40- 70-40(5%).
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Delphinium p. 130. 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 Very 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

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.

5% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Delphinium p. 130Public domain
Show the original text
Delphinium (Ranunculaceae). . This genus is composed of a group of medium heigth monocarpic species typified by D. geyeri germ. 57% at the end of March from outdoor sowing in late fall. Germination dropped to 5% when sown at 70 or 40 as shown by 70-40(5%)-70 and 40- 70-40(5%).
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Delphinium p. 130. 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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