Weld

Weld: how do you recognise it?

Habit

Biennial; a rosette in the first year, a straight, almost unbranched flowering stem 1–1.5 m high and about 40 cm wide in the second.

Leaves

Narrow lance-shaped, 5–15 cm, glossy green, with a wavy edge; the rosette stays green through winter.

Flowers

Small greenish-yellow flowers in long, slender spikes, from June to August, rich in nectar and pollen.

Fruit

Small open capsules with many fine black seeds, which self-sow.

Roots

A sturdy taproot; transplanting works only while the plants are still small.

Flowering: June–August · Sowing: April–May and September

Why grow it?

• A native plant that attracts wild bees, especially solitary bees, and many other insects.
• Slender, almost architectural spikes of 1–1.5 m add height and structure to a wild border.
• Grows where little else will: poor, dry, chalky soil in full sun.
• Drought tolerant and fully hardy, with no care needed.
• Historically interesting: the whole plant yields a yellow dye that was used for centuries to dye wool and silk.

Weld: where does it grow best?

• Full sun for the sturdiest, straightest spikes; in light partial shade it becomes floppier.
• Poor, free-draining soil: sand, loam or clay, neutral to chalky. Rich soil makes it floppy.
• Dry to normally moist; it tolerates drought well once established.
• An open, airy spot; in a windy site tall spikes may bend, so plant them among other plants.
• Allow 30–40 cm between plants.

Light

Sun

Soil type

Sand, loam or clay

Acidity

Neutral or chalky

Moisture

Dry or normal

Size

1.5 m tall, 0.4 m wide

Hardiness

Hardy (to -20 °C)

Goes well with

• Viper’s bugloss: Another native bee plant for dry, chalky soil, with blue flowers.
• Chicory: Sky-blue flowers in the same sunny, dry corner.
• Musk mallow: Soft pink flowers next to the slender yellow spikes.
• Ox-eye daisy: White and yellow in an airy, wild border.

Weld: when and how to plant it?

1. Sow in place in April–May or in September; transplanting only works while the seedlings are still small (taproot).
2. Loosen the soil, remove weeds and rake it fine; extra compost is not needed.
3. Scatter the seed thinly and just press it in: it needs light to germinate and is not covered, or barely.
4. Keep the soil lightly moist until germination (after 1–3 weeks).
5. Thin the seedlings to 30–40 cm between plants.
6. In the first year you see only the rosette; flowering follows only in the second year.

Care

Water

Only the seedlings in a long drought. Mature plants cope by themselves.

Feeding

Not needed; on poor soil it stays compact and sturdy.

Support

Usually not needed; in a windy spot the spikes stand better among other plants.

Seed set

If you do not want self-sown seedlings, cut the spikes off after flowering before the seed ripens.

Harvesting for dye

To use it as a dye plant, harvest the whole plant above ground during flowering in June–July.

Tip: Sow weld in place on poor, chalky soil in full sun and do not cover the seed. In the first year it makes only a rosette; leave it, because in the second year the 1.5 m spikes follow.

Weld: when to prune it?

When: It is not pruned; at most cut off the faded spikes before the seed ripens (August), or leave them.

How:

• Cut off the faded spikes in August if you want to limit self-seeding.
• Leave a few spikes if you want it to self-sow or birds to eat the seed.
• Pull out the dead plants in autumn after seed set.

Caution: It self-sows readily, especially on open, chalky or disturbed ground. Cut the seed heads off before the seed ripens if you do not want seedlings everywhere.

Pruning calendar and basic rules

Propagation

Sowing (spring)

In April–May in place: sow thinly, press the seed in without covering it and thin to 30–40 cm. It flowers only in the second year.

Sowing (late summer)

In September in place: a late-summer sowing gives strong rosettes that flower the following year.

Self-seeding

Let a few spikes ripen in July–August; the seed falls by itself and gives new plants next spring.

Weld: how does it get through the winter?

Hardy to −20 °C.

• Fully hardy, down to about −20 °C or colder: the rosette stays green through winter and needs no protection.
• Leave the rosette in place; it flowers in the second year and dies after setting seed.
• In a pot it is less suitable because of the taproot; sow it in place in the open ground instead.

Diseases and pests

• Slugs: Young seedlings are eaten. Collect slugs in the evening and sow a little more thickly, then thin out later.
• Aphids: On the flower spikes in June–July. Ladybirds and hoverflies usually clear them; otherwise spray off with water.
• Powdery mildew: White powdery coating on the leaves in drought and humid air. Give space and airflow, cut off affected parts.
• No flowers in the first year: Not a problem: weld is biennial and flowers only in the second year.
• Spikes falling over: On rich soil or in windy spots the long spikes bend. Choose poor soil and plant among other plants.

Through the year

• March: Remove weeds and loosen the soil before sowing.
• April: Sow in place. Do not cover the seed.
• May: Sow and thin to 30–40 cm.
• June: Second-year plants flower. Butterflies and bees visit the spikes.
• July: Full flower. Optionally harvest the whole plant for dyeing.
• August: Seed ripens. Cut off faded spikes or leave them.
• September: Sow for next year. Clear away dead plants.
• October: The rosette stays green over winter, do nothing.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• The yellow dye of weld contains luteolin; combined with the blue of woad, weld gave the green used to dye wool for centuries.
• Some wild bees, such as the large yellow-face bee (Hylaeus signatus), collect their pollen preferentially from mignonette plants.
• In its first year weld makes only a rosette; in the second year it flowers, sets seed and dies.