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Phlox divaricata

Genus 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
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.

Source: Extension Gardener Plant Toolbox — NC State Extension.

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 December 27, 2026 for a May 3 last frost. Too late for spring 2027 — that needed starting on December 26, 2025.

  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 15 months from start to sowing. Then 15 days to germinate.

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 April 17, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on April 16, 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 9 months from start to sowing. Then 84 days to germinate.

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 January 6, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on January 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 15 months from start to sowing. Then 5 days to germinate.

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 March 31, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on March 30, 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 12 months from start to sowing. Then 11 days to germinate.

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.

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