Prickly lettuce

How to recognise it

Habit

Upright plant of 30–150 cm with a single sturdy stem topped by a large, pyramid-shaped flower cluster; first a rosette in autumn or spring.

Leaf

Bluish-green and oblong, often deeply cut into backward-pointing lobes; the base clasps the stem with two arrow-shaped lobes. A row of small prickles runs under the midrib.

Flower

Pale yellow heads of 1–1.3 cm with only ray florets, in a large, open cluster, from July to September; they are mainly open in the morning.

Fruit/Seed

Flat, greyish-brown seeds with a long beak and a white pappus.

Stem

Pale, often prickly near the base; when damaged it oozes white, bitter milky sap.

Confused with

Great lettuce is often taller, with less deeply cut, often purple-tinged leaves and seeds that turn black when ripe; it is more poisonous. Sow-thistles have larger, golden-yellow flower heads and no row of prickles under the midrib.

Flowering: July–September · Pruning: August–September

Why grow it?

• Seed for birds: goldfinches and other seed-eaters love the fluffy seeds in late summer.
• The small flowers are visited by hoverflies and wild bees.
• A fascinating ‘compass plant’: in the sun its leaves turn to face north and south.
• Interesting for vegetable growers: the wild relative of butterhead, iceberg and other lettuces.
• Very young leaves are edible and were once eaten as a bitter green, but they soon become very bitter.

Prickly lettuce: where does it grow best?

• In the wild: verges, railway land, waste ground, building sites, docklands, walls, rubble and field edges.
• Full sun; warm and open.
• Dry to moderately moist, stony, sandy or limy soil, including fertile ground.
• In the garden: it often appears on its own in a gravel garden, between paving or in a sunny rough patch; leave a few for the birds.

Goes well with

• Wild carrot: White umbels on the same sunny, dry rough ground.
• Chicory: Sky blue beside the pale yellow, and also related to lettuce.
• Viper’s bugloss: Blue spikes for bees on the same dry soil.
• Wild mignonette: Pale yellow spikes on disturbed, limy ground.
• Teasel: Another seed supplier for goldfinches in winter.

Prickly lettuce: when and how to plant it?

1. Prickly lettuce usually arrives by itself; you seldom need to sow it.
2. If you do want it, sow seed of native origin in March–April or in September on a sunny, open spot.
3. Sow thinly, press the seed in, barely cover it and keep the soil moist until germination.
4. Thin the seedlings to 30–50 cm.
5. Choose a spot where it does no harm: it self-sows easily.
6. Never dig up plants in nature reserves.

Care

Water

Not needed; with its deep taproot it is built for drought.

Feeding

Not needed.

Spreading

Pull up young rosettes or dig them out with a weeding knife before the taproot goes too deep.

Letting it seed

Let a few plants ripen for the birds and cut the rest before the fluff is released.

Harvesting

Pick only very young leaves from rosettes in spring; older leaves are very bitter.

Tip: On a sunny day, put a compass next to a plant: you will see that most of the leaves are neatly lined up north–south.

Pruning and mowing

Pruning months: August–September.

When: In August–September, before the seed ripens, or after it has dispersed.

How:

• Cut or pull the plants before the fluff is released, if you do not want seedlings.
• Leave a few plants standing until the birds have eaten the seed.
• Leave the hollow, dry stems standing over winter for insects.
• Wear gloves: the stems and leaves prickle and the milky sap is sticky.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

Ripens from August; the fluff blows away on the wind. Sow where it is to grow in autumn or spring.

Prickly lettuce: how does it get through the winter?

Hardy to −20 °C.

• Plants that germinate in late summer or autumn overwinter as a rosette and flower the following year.
• Flowering plants die after setting seed; the dry stems remain standing like skeletons.
• The rosettes are hardy to about −20 °C.
• In autumn and early winter, birds pick the last seeds from the flower clusters.

Diseases and pests

• Self-sowing: It can come up in masses on bare, sunny ground. Weed out young plants or stop them setting seed.
• Mix-up with great lettuce: Great lettuce is more poisonous. Only eat leaves from plants you are sure of.
• Aphids: On the tips in summer; ladybirds and hoverflies usually deal with them.
• Taproot: Older plants are hard to pull up. Tackle them while they are small, or cut them before they flower.

Through the year

• March: Rosettes are growing; young leaves are still mild.
• April: Sow, or weed out surplus seedlings.
• May: Look at the ‘compass leaves’ on a sunny day.
• June: The flowering stem shoots up.
• July: First pale yellow flowers, open in the morning.
• August: Flowers and first fluff; cut if you do not want seed.
• September: Seed ripens; goldfinches come to feed. You can sow now.
• November: Leave the dry stems standing for insects.

Did you know?

• In full sun the leaves turn to face north and south: that way they catch light in the morning and evening, but only their edges face the fierce midday sun. Hence its other name, compass plant.
• Lactuca comes from the Latin lac, milk, after the plant’s white milky sap.
• Lettuce was already grown in ancient Egypt and is shown in wall paintings in tombs.