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Isatis tinctoria

Dyer's Woad · Woad · Asp-of-Jerusalem

Family BrassicaceaeGenus Isatis

Frothy sprays of tiny bright yellow four-petalled flowers
FlowerPethanCC BY-SA 3.0

About the plant

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

The plant

Habit
Herbaceous PerennialExtension Gardener Plant Toolbox
Habit
biennialPlants of the World Online
Height
2-4 ft0.6-1.2 mExtension Gardener Plant Toolbox
Spread
2-3 ft60-90 cmExtension Gardener Plant Toolbox
Flower
Gold/YellowExtension Gardener Plant Toolbox
Blooms
SpringExtension Gardener Plant Toolbox
Native range
Albania, Bulgaria, Greece, Italy, Krym, NW. Balkan Pen. and elsewhereGBIF Backbone Taxonomy
Hardiness zones
4-8Extension Gardener Plant Toolbox

Growing conditions

Sun
Full sunExtension Gardener Plant Toolbox
Soil
Loam (Silt), SandExtension Gardener Plant Toolbox
Soil pH
Alkaline (>8.0), 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; GBIF Backbone Taxonomy — Global Biodiversity Information Facility.

Worth knowing

  • Woad, a blue dye from its leaves, made towns such as Toulouse prosperous in medieval times. From the 16th century indigo began to replace it. Wikipedia: Isatis tinctoria
  • Its seeds have been found at Neolithic sites, in the cave of l'Audoste in France. Tinctoria refers to its use as a dye. Wikipedia: Isatis tinctoria

This source reports three treatments. All are shown.

Protocol 1

DerivedN. C. Deno, 1996

Difficulty Low Rated by us, not by the source.

Start around April 2, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on April 1, 2025.

  1. Dry storage

    Duration: 730 daysTemperature: 70°F 21°C

  2. Sow and cover

    Temperature: 70°F 21°C Light: dark

about 2 years from start to sowing. Then 4 days to germinate.

100% germination in 2–4 days.

Seed Germination Theory and Practice, 1st Supplement — N. C. Deno, 1996 · 1st Supplement, Isatis p. 50Public domain
Show the original text
Isatis (Brassicaceae). I. tinctoria germ. 40(96% in 2nd w) and 5% in 2nd w in 70D or 70L. Removing the outer husk increased the percent germination in 70D to 15%. Seeds DS 2 y germ. 70D(100% ïn 2-4 d) and 40(55% in 3-11 w)-70D(28% on 3rd d). The DS for 2 y seemed to change the germination pattern, but the seeds were still completely viable.
Seed Germination Theory and Practice, 1st Supplement, 1st Supplement, Isatis p. 50. 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, 1996

Difficulty Low Rated by us, not by the source.

Start around March 22, 2027 for a May 3 last frost.

  1. Cold moist stratification

    Temperature: 40°F 4°C

Germination happens during step 1, in 14 days.

96% germination in 14 days.

Seed Germination Theory and Practice, 1st Supplement — N. C. Deno, 1996 · 1st Supplement, Isatis p. 50Public domain
Show the original text
Isatis (Brassicaceae). I. tinctoria germ. 40(96% in 2nd w) and 5% in 2nd w in 70D or 70L. Removing the outer husk increased the percent germination in 70D to 15%. Seeds DS 2 y germ. 70D(100% ïn 2-4 d) and 40(55% in 3-11 w)-70D(28% on 3rd d). The DS for 2 y seemed to change the germination pattern, but the seeds were still completely viable.
Seed Germination Theory and Practice, 1st Supplement, 1st Supplement, Isatis p. 50. 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 Moderate Rated by us, not by the source.

Start around January 19, 2027 for a May 3 last frost. Too late for spring 2027 — that needed starting on January 18, 2025.

  1. Dry storage

    Duration: 730 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 Light: dark

    28 germinated in this phase.

Steps after step 2 run on after germination.

about 2 years from start to step 2. Germination happens during step 2, in 77 days.

55% germination in 21–77 days.

Seed Germination Theory and Practice, 1st Supplement — N. C. Deno, 1996 · 1st Supplement, Isatis p. 50Public domain
Show the original text
Isatis (Brassicaceae). I. tinctoria germ. 40(96% in 2nd w) and 5% in 2nd w in 70D or 70L. Removing the outer husk increased the percent germination in 70D to 15%. Seeds DS 2 y germ. 70D(100% ïn 2-4 d) and 40(55% in 3-11 w)-70D(28% on 3rd d). The DS for 2 y seemed to change the germination pattern, but the seeds were still completely viable.
Seed Germination Theory and Practice, 1st Supplement, 1st Supplement, Isatis p. 50. 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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