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Catalpa bignonioides

American Catalpa · Caterpillar Tree · Indian Bean Tree · Southern Catalpa

Family BignoniaceaeGenus Catalpa

An upright branched head of white frilled trumpet flowers marked yellow and purple, with broad heart-shaped leaves against a blue sky
FlowerZeynel CebeciCC BY-SA 4.0

About the plant

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

The plant

Habit
treePlants of the World Online
Habit
Perennial, TreePLANTS Database
Height
30-60 ft9-18 mExtension Gardener Plant Toolbox
Spread
20-40 ft6-12 mExtension Gardener Plant Toolbox
Flower
Purple/Lavender, WhiteExtension Gardener Plant Toolbox
Blooms
SummerExtension Gardener Plant Toolbox
Native range
Alabama, Florida, Georgia, Louisiana, Mississippi, TexasGBIF Backbone Taxonomy
Hardiness zones
5-9Extension Gardener Plant Toolbox

Growing conditions

Sun
Full sun; Partial ShadeExtension Gardener Plant Toolbox
Soil
Clay, Loam (Silt), SandExtension Gardener Plant Toolbox
Soil pH
Acid (<6.0), Alkaline (>8.0), Neutral (6.0-8.0)Extension Gardener Plant Toolbox
Moisture
Good Drainage, MoistExtension Gardener Plant Toolbox
Watering
Drought tolerance: MediumPLANTS Database

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; Extension Gardener Plant Toolbox — NC State Extension; GBIF Backbone Taxonomy — Global Biodiversity Information Facility.

Worth knowing

Three sources report 8 treatments between them. All are shown.

Protocol 1

DerivedN. C. Deno, 1998

Difficulty Low Rated by us, not by the source.

Start around March 16, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on March 16, 2023.

  1. Dry storage

    Duration: 1460 daysTemperature: 70°F 21°C

  2. Sow and cover

    Temperature: 70°F 21°C Light: light

about 4 years from start to sowing. Then 21 days to germinate.

78% germination in 21 days.

Seed Germination Theory and Practice, 2nd Supplement — N. C. Deno, 1998 · 2nd Supplement, Catalpa p. 23Public domain
Show the original text
Catalpa (Bignoniaceae). G. bignonioides seeds DS 4 y germ. 70D(2/12 in 2nd w) and 70L(7/9 in 3rd w). The light requirement is still largely présent although it appears to be slowiy disappearing in accord with data in the 2nd Ed.
Seed Germination Theory and Practice, 2nd Supplement, 2nd Supplement, Catalpa p. 23. 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, 1998

Difficulty High Rated by us, not by the source.

Start around March 23, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on March 23, 2023.

  1. Dry storage

    Duration: 1460 daysTemperature: 70°F 21°C

  2. Sow and cover

    Temperature: 70°F 21°C Light: dark

about 4 years from start to sowing. Then 14 days to germinate.

17% germination in 14 days.

Seed Germination Theory and Practice, 2nd Supplement — N. C. Deno, 1998 · 2nd Supplement, Catalpa p. 23Public domain
Show the original text
Catalpa (Bignoniaceae). G. bignonioides seeds DS 4 y germ. 70D(2/12 in 2nd w) and 70L(7/9 in 3rd w). The light requirement is still largely présent although it appears to be slowiy disappearing in accord with data in the 2nd Ed.
Seed Germination Theory and Practice, 2nd Supplement, 2nd Supplement, Catalpa p. 23. 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, 1996

Difficulty Low Rated by us, not by the source.

Start around March 24, 2027 for a May 3 last frost.

  1. Sow and cover

    Temperature: 70°F 21°C Light: light

No stated waiting before sowing. Then 12 days to germinate.

100% germination in 5–12 days.

Seed Germination Theory and Practice, 1st Supplement — N. C. Deno, 1996 · 1st Supplement, Catalpa p. 29Public domain
Show the original text
Catalpa (Bignonicaceae). C. bignonioides fresh seeds germ. only in light or GA-3 treatment, but this slowly disappeared on DS (2nd Ed.). Experiments were conducted to see if Irradiating the seeds while dry would destroy the system blocking germination, but this was totally unsuccessful. Seeds irradiated eight inches under 40 watt fluorescent light for up to 50 d germ. germ, 70L(100% in 5-12 d) and 70D(none) the same as seeds not irradiated.
Seed Germination Theory and Practice, 1st Supplement, 1st Supplement, Catalpa p. 29. 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 Low Rated by us, not by the source.

Start around March 30, 2027 for a May 3 last frost.

  1. Gibberellic acid soak

  2. Sow and cover

    Temperature: 70°F 21°C Light: dark

No stated waiting before sowing. Then 6 days to germinate.

100% germination in 6 days.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Catalpa p. 114Public domain
Show the original text
Catalpa (Bignoniaceae). C. bignonioides required light, GA-3, or DS for germination. The data for seed collected in October were 70L(1 00% in 1-3 w), 70D GA- 3(100% on 6th d), and 70D(none). The light requirement gradually disappears on DS. For example seeds collected in March (already extensive DS) germ. 70(44%)-40(2%)- 70(47%) and 40-70(32%) and the same seeds given a further 6 m DS at 70 germ. 70(76%) and 40-70(94%). Where germination was incomplete, the remaining seeds would germinate immediately on shifting to 70L even after three dark cycles.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Catalpa p. 114. 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 June 19, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on June 18, 2026.

  1. Dry storage

    Duration: 180 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

about 9 months from start to step 3. Germination happens during step 3; time not stated, 21 days assumed.

94% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Catalpa p. 114Public domain
Show the original text
Catalpa (Bignoniaceae). C. bignonioides required light, GA-3, or DS for germination. The data for seed collected in October were 70L(1 00% in 1-3 w), 70D GA- 3(100% on 6th d), and 70D(none). The light requirement gradually disappears on DS. For example seeds collected in March (already extensive DS) germ. 70(44%)-40(2%)- 70(47%) and 40-70(32%) and the same seeds given a further 6 m DS at 70 germ. 70(76%) and 40-70(94%). Where germination was incomplete, the remaining seeds would germinate immediately on shifting to 70L even after three dark cycles.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Catalpa p. 114. 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 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. Sow and cover

    Temperature: 70°F 21°C

about 6 months from start to sowing. Germination time not stated; 21 days assumed.

76% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Catalpa p. 114Public domain
Show the original text
Catalpa (Bignoniaceae). C. bignonioides required light, GA-3, or DS for germination. The data for seed collected in October were 70L(1 00% in 1-3 w), 70D GA- 3(100% on 6th d), and 70D(none). The light requirement gradually disappears on DS. For example seeds collected in March (already extensive DS) germ. 70(44%)-40(2%)- 70(47%) and 40-70(32%) and the same seeds given a further 6 m DS at 70 germ. 70(76%) and 40-70(94%). Where germination was incomplete, the remaining seeds would germinate immediately on shifting to 70L even after three dark cycles.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Catalpa p. 114. 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 March 21, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on March 20, 2026.

  1. Dry storage

    Duration: 180 daysTemperature: 70°F 21°C

  2. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

    44 germinated in this phase.

  3. Cold moist stratification

    Duration: 90 daysTemperature: 40°F 4°C

    2 germinated in this phase.

  4. Warm moist stratification

    Duration: 90 daysTemperature: 70°F 21°C

about 12 months from start to step 4. Germination happens during step 4; time not stated, 21 days assumed.

47% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Catalpa p. 114Public domain
Show the original text
Catalpa (Bignoniaceae). C. bignonioides required light, GA-3, or DS for germination. The data for seed collected in October were 70L(1 00% in 1-3 w), 70D GA- 3(100% on 6th d), and 70D(none). The light requirement gradually disappears on DS. For example seeds collected in March (already extensive DS) germ. 70(44%)-40(2%)- 70(47%) and 40-70(32%) and the same seeds given a further 6 m DS at 70 germ. 70(76%) and 40-70(94%). Where germination was incomplete, the remaining seeds would germinate immediately on shifting to 70L even after three dark cycles.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Catalpa p. 114. 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 Moderate Rated by us, not by the source.

Start around June 19, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on June 18, 2026.

  1. Dry storage

    Duration: 180 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

about 9 months from start to step 3. Germination happens during step 3; time not stated, 21 days assumed.

32% germination.

Seed Germination Theory and Practice, 2nd ed. — N. C. Deno, 1993 · Ch. 20, Catalpa p. 114Public domain
Show the original text
Catalpa (Bignoniaceae). C. bignonioides required light, GA-3, or DS for germination. The data for seed collected in October were 70L(1 00% in 1-3 w), 70D GA- 3(100% on 6th d), and 70D(none). The light requirement gradually disappears on DS. For example seeds collected in March (already extensive DS) germ. 70(44%)-40(2%)- 70(47%) and 40-70(32%) and the same seeds given a further 6 m DS at 70 germ. 70(76%) and 40-70(94%). Where germination was incomplete, the remaining seeds would germinate immediately on shifting to 70L even after three dark cycles.
Seed Germination Theory and Practice, 2nd ed., Ch. 20, Catalpa p. 114. 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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