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Phlox divaricata

Wild Blue Phlox · Woodland Phlox · Wild Sweet William

Family PolemoniaceaeGenus Phlox

Flat lavender-blue flowers with five notched lobes and white eyes, in loose heads above dark narrow leaves.
FlowerWilson44691CC0

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
0.5-1 ft15-30 cmExtension Gardener Plant Toolbox
Spread
0.8-1.7 ft25-50 cmExtension Gardener Plant Toolbox
Flower
Blue, Purple/LavenderExtension Gardener Plant Toolbox
Blooms
SpringExtension Gardener Plant Toolbox
Hardiness zones
3-8Extension Gardener Plant Toolbox

Growing conditions

Sun
Dappled Sunlight; Deep shade; Partial ShadeExtension Gardener Plant Toolbox
Soil
Clay, High Organic Matter, Loam (Silt), SandExtension Gardener Plant Toolbox
Soil pH
Acid (<6.0), Neutral (6.0-8.0)Extension Gardener Plant Toolbox
Moisture
Good Drainage, MoistExtension 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.

Worth knowing

This source reports 4 treatments. All are shown.

Protocol 1

DerivedN. C. Deno, 1993

Difficulty High Rated by us, not by the source.

Start around March 27, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on March 26, 2026.

  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

    12 germinated in this phase.

  4. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    30 germinated in this phase.

  5. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

  6. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  7. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

    3 germinated in this phase.

Steps after step 5 run on after germination.

about 12 months from start to step 5. Germination happens during step 5, in 15 days.

37% germination in 15 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Phlox p. 191Public domain
Show the original text
Phlox (Polemonlaceae). Phlox seed is hard to collect as there are only a few seed in each spherical capsule and these capsules roll away as soon as ripe. As a result seed of Phlox is not readily available except for the annual P. divaricata germ. 70-40-70(7%)-40-70(27% in 1-5 d) and 40-70(4%)-40(33% in 12th w)-70(18% in 2-3 d) using fresh seed. A second sample germ. 70-40-70(12%)- 40(30%)-70(37% in 15 d)-40-70(3%) and 40(2%)-70(13%)-40(8%)-70(25% in 1-11 d). Germination is extended although details vary. DS is deleterious although a few seeds survive DS for 6 m at 70.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Phlox p. 191. 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 July 16, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on July 15, 2026.

  1. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  2. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

    4 germinated in this phase.

  3. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  4. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

    18 germinated in this phase.

Steps after step 3 run on after germination.

about 6 months from start to step 3. Germination happens during step 3, in 84 days.

33% germination in 84 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Phlox p. 191Public domain
Show the original text
Phlox (Polemonlaceae). Phlox seed is hard to collect as there are only a few seed in each spherical capsule and these capsules roll away as soon as ripe. As a result seed of Phlox is not readily available except for the annual P. divaricata germ. 70-40-70(7%)-40-70(27% in 1-5 d) and 40-70(4%)-40(33% in 12th w)-70(18% in 2-3 d) using fresh seed. A second sample germ. 70-40-70(12%)- 40(30%)-70(37% in 15 d)-40-70(3%) and 40(2%)-70(13%)-40(8%)-70(25% in 1-11 d). Germination is extended although details vary. DS is deleterious although a few seeds survive DS for 6 m at 70.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Phlox p. 191. 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 High Rated by us, not by the source.

Start around April 6, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on April 5, 2026.

  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

    7 germinated in this phase.

  4. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

  5. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

about 12 months from start to step 5. Germination happens during step 5, in 5 days.

27% germination in 1–5 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Phlox p. 191Public domain
Show the original text
Phlox (Polemonlaceae). Phlox seed is hard to collect as there are only a few seed in each spherical capsule and these capsules roll away as soon as ripe. As a result seed of Phlox is not readily available except for the annual P. divaricata germ. 70-40-70(7%)-40-70(27% in 1-5 d) and 40-70(4%)-40(33% in 12th w)-70(18% in 2-3 d) using fresh seed. A second sample germ. 70-40-70(12%)- 40(30%)-70(37% in 15 d)-40-70(3%) and 40(2%)-70(13%)-40(8%)-70(25% in 1-11 d). Germination is extended although details vary. DS is deleterious although a few seeds survive DS for 6 m at 70.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Phlox p. 191. 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 High Rated by us, not by the source.

Start around June 29, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on June 28, 2026.

  1. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    2 germinated in this phase.

  2. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

    13 germinated in this phase.

  3. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    8 germinated in this phase.

  4. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

about 9 months from start to step 4. Germination happens during step 4, in 11 days.

25% germination in 1–11 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Phlox p. 191Public domain
Show the original text
Phlox (Polemonlaceae). Phlox seed is hard to collect as there are only a few seed in each spherical capsule and these capsules roll away as soon as ripe. As a result seed of Phlox is not readily available except for the annual P. divaricata germ. 70-40-70(7%)-40-70(27% in 1-5 d) and 40-70(4%)-40(33% in 12th w)-70(18% in 2-3 d) using fresh seed. A second sample germ. 70-40-70(12%)- 40(30%)-70(37% in 15 d)-40-70(3%) and 40(2%)-70(13%)-40(8%)-70(25% in 1-11 d). Germination is extended although details vary. DS is deleterious although a few seeds survive DS for 6 m at 70.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Phlox p. 191. 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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