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Oenothera brachycarpa

Shortfruit Evening Primrose

Family OnagraceaeGenus Oenothera

A pale yellow flower over a flat rosette of gray-green leaves on rock
FlowerPatrick Alexander from Las Cruces, NMCC0

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
Pale yellow, yellowFlora of North America
Native range
Arizona, Mexico Northeast, Mexico Northwest, New Mexico, TexasGBIF 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.

This source reports 8 treatments. All are shown.

Protocol 1

DerivedN. C. Deno, 1993

Difficulty Low 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. Cold moist stratification

    Temperature: 40°F 4°C

about 6 months from start to step 2. Germination happens during step 2; time not stated, 21 days assumed.

77% germination.

The best result by far, and an odd one: store it dry warm, then sow it cold.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, OenotheraPublic domain
Show the original text
Oenothera (Onagraceae). While many species germ. well in dark treatments, 0. biennis has an absolute light requirement so that photorequirements have to be considered in this genus. 0. brachycarpa germ. 70(39% largely in 2-3 d) and 40(33% in 1-10 w)-70(49% in 1-5 d) for fresh seed and 70(11%) and 40(77%) for seed DS 6 m at 70..
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Oenothera. 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 Low 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. Cold moist stratification

    Temperature: 40°F 4°C

about 6 months from start to step 2. Germination happens during step 2; time not stated, 21 days assumed.

77% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Oenothera p. 181Public domain
Show the original text
Oenothera (Onagraceae). While many species germ. well in dark treatments, 0. brachycarpa germ. 70(39% largely in 2-3 d) and 40(33% in 1-10 w)-70(49% in 1-5 d) for fresh seed and 70(11%) and 40(77%) for seed DS 6 m at 70..
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Oenothera p. 181. 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 December 31, 2026 for a May 3 last frost.

  1. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    33% germinated at 40 itself, over 1-10 weeks. Deno gives no length for this period; three months is his standard cycle.

  2. Warm moist stratification

    Temperature: 70°F 21°C

    A further 49%, in 1-5 days.

about 3 months from start to step 2. Germination happens during step 2, in 5 days.

49% germination in 1–5 days.

33% comes up in the cold itself, then 49% within days of the move.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, OenotheraPublic domain
Show the original text
Oenothera (Onagraceae). While many species germ. well in dark treatments, 0. biennis has an absolute light requirement so that photorequirements have to be considered in this genus. 0. brachycarpa germ. 70(39% largely in 2-3 d) and 40(33% in 1-10 w)-70(49% in 1-5 d) for fresh seed and 70(11%) and 40(77%) for seed DS 6 m at 70..
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Oenothera. 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 December 31, 2026 for a May 3 last frost.

  1. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    33 germinated in this phase.

  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 5 days.

49% germination in 1–5 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Oenothera p. 181Public domain
Show the original text
Oenothera (Onagraceae). While many species germ. well in dark treatments, 0. brachycarpa germ. 70(39% largely in 2-3 d) and 40(33% in 1-10 w)-70(49% in 1-5 d) for fresh seed and 70(11%) and 40(77%) for seed DS 6 m at 70..
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Oenothera p. 181. 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 April 2, 2027 for a May 3 last frost.

  1. Sow and cover

    Temperature: 70°F 21°C

No stated waiting before sowing. Then 3 days to germinate.

39% germination in 2–3 days.

Fresh seed at 70 is quick but partial: 39%, most of it in two or three days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, OenotheraPublic domain
Show the original text
Oenothera (Onagraceae). While many species germ. well in dark treatments, 0. biennis has an absolute light requirement so that photorequirements have to be considered in this genus. 0. brachycarpa germ. 70(39% largely in 2-3 d) and 40(33% in 1-10 w)-70(49% in 1-5 d) for fresh seed and 70(11%) and 40(77%) for seed DS 6 m at 70..
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Oenothera. 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 Moderate Rated by us, not by the source.

Start around April 2, 2027 for a May 3 last frost.

  1. Sow and cover

    Temperature: 70°F 21°C

No stated waiting before sowing. Then 3 days to germinate.

39% germination in 2–3 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Oenothera p. 181Public domain
Show the original text
Oenothera (Onagraceae). While many species germ. well in dark treatments, 0. brachycarpa germ. 70(39% largely in 2-3 d) and 40(33% in 1-10 w)-70(49% in 1-5 d) for fresh seed and 70(11%) and 40(77%) for seed DS 6 m at 70..
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Oenothera p. 181. 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 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. Germination time not stated; 21 days assumed.

11% germination.

Dry storage then warmth is the worst of the four: 11%, against 77% sown cold.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, OenotheraPublic domain
Show the original text
Oenothera (Onagraceae). While many species germ. well in dark treatments, 0. biennis has an absolute light requirement so that photorequirements have to be considered in this genus. 0. brachycarpa germ. 70(39% largely in 2-3 d) and 40(33% in 1-10 w)-70(49% in 1-5 d) for fresh seed and 70(11%) and 40(77%) for seed DS 6 m at 70..
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Oenothera. 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 8

DerivedN. C. Deno, 1993

Difficulty 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. 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. Germination time not stated; 21 days assumed.

11% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Oenothera p. 181Public domain
Show the original text
Oenothera (Onagraceae). While many species germ. well in dark treatments, 0. brachycarpa germ. 70(39% largely in 2-3 d) and 40(33% in 1-10 w)-70(49% in 1-5 d) for fresh seed and 70(11%) and 40(77%) for seed DS 6 m at 70..
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Oenothera p. 181. 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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