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Houstonia caerulea

Azure Bluet · Bluets · Quaker Ladies

Family RubiaceaeGenus Houstonia

A patch of small white four-petalled flowers with yellow eyes scattered through short grass
FlowerJomegatCC BY-SA 3.0

About the plant

What it is and where it grows — not part of any germination protocol.

The plant

Habit
Annual, Herbaceous Perennial, WildflowerExtension Gardener Plant Toolbox
Habit
subshrubPlants of the World Online
Height
3-6 in10-15 cmExtension Gardener Plant Toolbox
Spread
3-6 in10-15 cmExtension Gardener Plant Toolbox
Flower
Blue, Gold/Yellow, WhiteExtension Gardener Plant Toolbox
Blooms
Spring, SummerExtension Gardener Plant Toolbox
Native range
Canada, lower 48 statesPLANTS Database
Hardiness zones
3-8Extension Gardener Plant Toolbox

Growing conditions

Sun
Dappled Sunlight; Full sun; Partial ShadeExtension Gardener Plant Toolbox
Soil
High Organic Matter, Loam (Silt), Sand, Shallow RockyExtension Gardener Plant Toolbox
Soil pH
Acid (<6.0), Neutral (6.0-8.0)Extension Gardener Plant Toolbox
Moisture
Good Drainage, Moist, Occasionally DryExtension 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; PLANTS Database — USDA NRCS.

Worth knowing

This source reports two treatments. Both are shown.

Protocol 1

DerivedN. C. Deno, 1993

Difficulty Low Rated by us, not by the source.

Start around March 27, 2027 for a May 3 last frost.

  1. Sow and cover

    Temperature: 70°F 21°C

No stated waiting before sowing. Then 9 days to germinate.

85% germination in 6–9 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Houstonia p. 153Public domain
Show the original text
Houstonia (Rubiaceae). H. coerulea germ. 70(85% in 6-9 d) and 40(9%)- 70(21%). -
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Houstonia p. 153. 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 December 15, 2026 for a May 3 last frost.

  1. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    9 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; time not stated, 21 days assumed.

21% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Houstonia p. 153Public domain
Show the original text
Houstonia (Rubiaceae). H. coerulea germ. 70(85% in 6-9 d) and 40(9%)- 70(21%). -
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Houstonia p. 153. 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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