In its first year, wild lettuce (Lactuca virosa) looks like an overgrown head of lettuce. In its second year it shoots up into a stem that can reach two metres. Cut it and a white milky sap appears, which was once sold in pharmacies as lactucarium. In this post you'll learn how to identify wild lettuce, how to grow it from seed and what the plant contains.
What is wild lettuce?
Lactuca virosa belongs to the daisy family (Asteraceae) and is related to garden lettuce. It's native to central and southern Europe and the coasts of Great Britain, and has spread to North America and Australia through trade. In English it's also known as bitter lettuce, great lettuce and opium lettuce.
The plant is biennial. In its first year it forms only a rosette of large leaves. In its second year a sturdy, often purple-flushed stem grows up, carrying small yellow flower heads from July to September. These are followed by seeds with a fluffy parachute that drift away on the wind.
How to identify wild lettuce
- Large, blue-green leaves that clasp the stem with two small lobes.
- Small prickles along the underside of the midrib.
- A straight, often purple-spotted stem, 1 to 2 m (3 to 6.5 ft) tall.
- Small, pale yellow flower heads in a loose cluster.
- Purplish-black seeds with a white tuft.
- White milky sap as soon as a leaf or stem is damaged.
| Plant | Features | Difference from wild lettuce |
|---|---|---|
| Lactuca virosa (wild lettuce) | Leaves held horizontally, purplish-black seed | The species in this post |
| Lactuca serriola (prickly lettuce) | Leaves twist upright, like a compass needle | Very common, grey-brown to olive seed |
| Sonchus (sow thistle) | Softer, glossy leaves, larger yellow flowers | Flowers look more like dandelion |
| Lactuca sativa (garden lettuce) | No prickles, grown as a vegetable | Also has sap, but far less bitter |
What does it contain?
Wild lettuce sap dries in the air into a brown, resin-like mass. This is lactucarium, which 19th-century pharmacists sold as a mild substitute for opium. That's where the nickname "lettuce opium" comes from. It doesn't contain opium or morphine, though.
The best-known compounds are the bitter sesquiterpene lactones lactucin and lactucopicrin. They're chemically fairly unstable, so their content varies widely between commercial products. There's little modern clinical research on wild lettuce, and no approved health claims exist for the plant.
Which form suits you?
| Product | Form | What it is |
|---|---|---|
| Wild lettuce seeds | 10 seeds | For growing the plant yourself and getting to know it |
| Dried wild lettuce | Dried herb | The dried leaf of Lactuca virosa |
| Wild lettuce 10x extract | Extract, 5 grams | A concentrated form, much stronger than the leaf |
You'll also find the herb and extract in our relaxing herbs category. Avalon doesn't give usage advice. An extract is much stronger than leaf, so never compare products one to one.
Growing wild lettuce from seed
Wild lettuce is an easy outdoor plant, as long as you remember one thing: the seed likes cool weather.
- Pick your timing. Sow from March to May, or in August and September. Autumn sowings overwinter as a rosette and flower the following year.
- Sow on the surface. Scatter the seeds on moist soil and press them in. Cover them with no more than a wafer-thin layer of soil.
- Keep it cool and moist. The seed germinates best at around 15 to 20 °C (59 to 68 °F), usually within one to three weeks. Above 25 °C (77 °F) germination is poor.
- Optional: a cold treatment. Two to four weeks moist in the fridge can improve germination, but it isn't required.
- Prick out and plant out. Seedlings grow slowly at first. Plant them 30 cm (12 in) apart, just like ordinary lettuce.
- Give it room in year two. The flower stem gets tall. Choose a spot where it won't blow over, or give it a stake.
Position and care
- Light: sun to partial shade.
- Soil: free-draining, sandy or loamy. Both acidic and chalky soils are fine.
- Water: keep seedlings moist; mature plants are fairly drought tolerant.
- Hardiness: the rosette survives a normal northern European winter without problems.
Saving seed
After flowering, the plant forms hundreds of fluffy seeds that blow away. To save seed, cut the spent flower heads as soon as the first tufts appear and let them dry in a paper bag. If you don't want the plant to self-sow everywhere, cut the flower stems in time.
Common mistakes
- Sowing too deep: the seed needs light and won't come up.
- Sowing in summer heat: above 25 °C the seed hardly germinates.
- Growing indoors: wild lettuce wants cool, bright conditions and tends to get leggy indoors.
- Mixing it up with prickly lettuce: check the leaf position and seed colour.
- Letting everything self-sow: one plant can fill your whole garden with seed.
Safety
- The sap can irritate skin and eyes. Wear gloves when handling the stems.
- People allergic to plants in the daisy family, such as ragweed, chamomile or arnica, may also react to wild lettuce.
- Dizziness, dilated pupils and restlessness have been reported after use. Too little is known about use during pregnancy or breastfeeding or alongside medication: ask your doctor or pharmacist first.
- Keep the plant and products out of reach of children and pets.
Avalon doesn't give usage advice, and all our products are for adults aged 18 and over only. You'll find more background on Erowid.
Is wild lettuce legal?
Wild lettuce isn't banned in the Netherlands or elsewhere in Europe. You can grow the plant and buy the products. In the US state of Louisiana, Lactuca virosa may not be sold for human consumption. Always check the rules where you live.
Frequently asked questions
Is wild lettuce the same as garden lettuce?
No. It's a different species in the same genus. Wild lettuce is far more bitter and contains much more sap than garden lettuce.
Why is wild lettuce called "lettuce opium"?
Because its dried sap, lactucarium, was used in the 19th century as a mild substitute for opium. It contains no opium or morphine.
How long does the seed take to germinate?
At 15 to 20 °C with enough light, usually one to three weeks.
Does wild lettuce flower in its first year?
Usually not. In its first year it forms a leaf rosette, and the tall flower stem follows in the second. Plants sown early in spring sometimes flower the same year.
How do I tell it apart from prickly lettuce?
Prickly lettuce turns its leaves upright, like a compass needle, and has grey-brown seed. Wild lettuce keeps its leaves horizontal and has purplish-black seed.
Where can I buy wild lettuce?
You'll find wild lettuce seeds, dried wild lettuce and wild lettuce extract at Avalon. Curious about other relaxing herbs? Read the best herbs for relaxation.
Sources: Drugs.com Natural Products (Lettuce Opium), Strictly Medicinal Seeds, Earthsong Seeds.
