Woad

Woad: how do you recognise it?

Life cycle

Biennial: a leaf rosette in the first year, a flowering stem about 1 m tall in the second.

Leaves

Blue-green; the rosette leaves are lance-shaped and up to 15 cm long, the stem leaves arrow-shaped and clasping.

Flowers

Small, bright yellow, four-petalled flowers in loose panicles, in May–June.

Fruit

Flat, hanging, blackish-brown, one-seeded fruits from July.

Roots

A long, deep taproot: it makes the plant drought-tolerant, but it cannot be transplanted.

Flowering: May–June · Sowing: April–July · Pruning: June–July

Why grow it?

• Clouds of small, bright yellow flowers in May–June, when the border is not yet full.
• Bees and other insects like to visit the flowers.
• The blue-green leaf rosette is already decorative in the first year.
• A historic dye plant: fun in a herb or dye garden.
• Drought-tolerant and almost maintenance-free in sunny, lean soil.
• The hanging fruits look good in dried arrangements.

Woad: where does it grow best?

• Full sun.
• Well-drained soil: sand, loam or clay, neutral to chalky. Not too wet.
• Dry to normally moist; thanks to its deep taproot it survives drought.
• Lean to moderately fertile soil is enough; too much feeding gives floppy stems.
• Keep 30–40 cm between plants and choose a spot where it may self-seed.

Light

Sun

Soil type

Sand, loam or clay

Acidity

Neutral or chalky

Moisture

Dry or normal

Size

1 m tall, 0.4 m wide

Hardiness

Hardy (to -25 °C)

Goes well with

• Lavender: Likes the same sunny, dry spot.
• Cornflower: Blue flowers that look lovely beside the yellow woad.
• Poppy: Red accents in a natural annual border.
• Sage: Grey-green foliage and blue flowers in a herb border.

Woad: when and how to plant it?

1. Sow from April to July outdoors, in place: a taproot dislikes transplanting.
2. Loosen the soil, remove weeds and rake the surface fine.
3. Sow in rows 30 cm apart, about 1 cm deep, and cover the seed lightly.
4. Keep the soil moist until the seeds germinate, usually after 1–3 weeks.
5. Thin the seedlings to 30–40 cm apart.
6. A rosette forms in the first year; flowering follows in the second spring.

Care

Water

Only when sowing and in long droughts in the first year. After that it copes on its own.

Feeding

Not needed; it looks best in lean soil.

Weeding

In the first year keep the rosettes free of weeds; they compete poorly with fast-growing grass.

Support

Tall stems can blow over in strong wind. Plant in small groups or give a little support.

Harvesting leaves

For dyeing, pick young, healthy leaves from the rosettes in summer, cutting them with scissors.

Tip: If you want a yellow cloud every spring, let a few plants self-seed and cut the rest off before the fruits ripen. If you want to dye, harvest the leaves of the first-year rosettes.

Woad: when to prune it?

Pruning months: June–July.

When: Straight after flowering, in June–July, before the fruits ripen.

How:

• Cut the spent stems back to below the flower cluster, or the whole stem at the base.
• Leave a few stems if you want seed or want woad to return.
• After seeding the plant dies: clear it away in autumn.
• When weeding, remove unwanted seedlings.

Caution: Woad self-seeds massively and can run riot in sunny, lean soil. Cut the flower stems before the fruits ripen and clear away seedlings. In other countries it counts as a harmful weed.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Sowing

From April to July outdoors in place (see planting). Collect seed in July from the brown fruits.

Self-seeding

Let a few plants seed if you want new ones every year. Transplanting the seedlings works poorly because of the taproot.

Woad: how does it get through the winter?

Hardy to −25 °C.

• Fully hardy, to about −25 °C: the rosette overwinters without protection.
• On wet, heavy clay the rosette may rot away in winter: choose a well-drained soil.
• Leave the rosette in place; it starts growing again in March.

Diseases and pests

• Flea beetles: Small holes in the leaves of young plants in dry spring weather. Keep the soil moist or cover the seedbeds with fine insect mesh.
• Clubroot: Woad belongs to the cabbage family. Swollen, misshapen roots and failing plants. Do not sow where cabbages grew and remove affected plants.
• Downy mildew: Yellow patches with grey mould under the leaves in damp weather. Give plants room and cut off affected leaves.
• Slugs: They strip young seedlings. Collect them in the evening, spread a coarse material or let the seedlings get bigger first.

Through the year

• January: Rest. Leave the rosettes in place.
• February: Prepare the sowing spot and soil.
• March: The rosettes start growing again. Weed.
• April: Sow. The flower stems start to grow.
• May: Flowering begins. You can still sow.
• June: Flowering. Cut off the flower stems to prevent self-seeding. You can still sow.
• July: Last sowing. Collect seed. Harvest leaves.
• August: Harvest rosette leaves for dye. Weed.
• September: Check the seedlings. Weed.
• October: Let the rosettes overwinter. Clear spent plants.
• November: Tidy up.
• December: Rest.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• The blue pigment is chemically the same (indigotin) as that of the tropical indigo plant.
• Around Toulouse and in Thuringia the trade in woad dye made towns rich.
• The blue was obtained by fermenting the leaves; indigo from distant lands eventually displaced woad.