Sow Thistle – The Garden “Weed” Worth Getting to Know

Sonchus oleraceus

By Pam Burgess

What if that plant you have been pulling out of your garden isn't really a weed at all?

Sow thistle is one of those plants that many gardeners automatically remove, yet it has a long history as a food plant and traditional herbal plant. Here in Queensland, it can appear almost anywhere—from vegetable gardens and lawns to roadsides and neglected corners.

For those of us who are interested in making the most of what our gardens provide, sow thistle is certainly worth getting to know.

Getting to Know Sow Thistle

Sow thistle (Sonchus oleraceus) is a familiar plant throughout much of Australia and New Zealand and is also widespread in Britain and Ireland. It is native to Europe and western Asia.

It can grow to around 50–100 cm tall, developing branched, leafy stems and soft, grey-green leaves.

When growing vigorously in a well-fed garden, the young leaves can become surprisingly large. In poorer soil or neglected areas, the plants are often smaller and more scrappy.

The flowers are small and bright yellow. After flowering, they develop into familiar fluffy seed heads, with white parachute-like seeds that are easily carried by the wind.

How to recognise it

Look for:

• Soft, grey-green leaves
• Branched, leafy stems
• Yellow flowers resembling small dandelion flowers
• White, fluffy seed heads
• A white, milky sap when the plant is damaged

The milky sap is one of the characteristics that makes sow thistle easy to recognise.

Don't Confuse Sow Thistle with Milk Thistle

There is sometimes confusion over the name “milk thistle”.

Sow thistle is sometimes called milk thistle in common usage, but it is not the same plant as true milk thistle, Silybum marianum.

The two plants belong to different genera and have quite different appearances.

If you are collecting a wild plant for food or traditional use, correct identification is essential.

Never consume a wild plant unless you are completely confident about its identification.

Sow Thistle as a Food Plant

Young sow thistle leaves have traditionally been used as a leafy green or “pot herb”.

The tender leaves can be:

• Added to salads
• Cooked into soups
• Added to stews
• Cooked as a vegetable
• Combined with other leafy greens

As the plant gets older, the leaves can become tougher and more bitter, so young leaves are generally preferred for eating.

The stems can also be cooked, in much the same way that some people prepare other tender vegetable stems.

As with any wild or garden plant intended for eating, only collect plants that have been correctly identified and have grown in an area free from herbicides, pesticides, contaminated soil and other pollutants.

A Favourite with the Animals

Sow thistle isn't only appreciated by people.

When I had ducks and ducklings, they absolutely adored it. Before I understood all the possible uses of this plant for people, I regularly picked it for the animals.

They never seemed to miss an opportunity to gobble it up!

These days, because sheep graze around my house, I rarely find sow thistle in the lawn. It tends to survive in the fenced-off garden areas where the sheep cannot reach it.

Puha – A Traditional New Zealand Food

Sow thistle is also known as puha and has an important place in traditional Māori food culture in New Zealand.

The young greens have traditionally been eaten as a vegetable and added to hearty dishes, including meals containing meat.

This is a wonderful reminder that plants we often dismiss as weeds can have a long history of use as food.

Sow Thistle in Traditional Herbal Use

Sow thistle has also been used traditionally in herbal practices.

The plant produces a white, milky latex when damaged, and this has featured in various folk remedies. Traditional uses have included preparations for skin complaints and other everyday ailments.

Sow thistle has also been associated in folk tradition with pain relief and supporting lactation.

However, traditional use should not be confused with established medical treatment. There is not enough reliable clinical evidence to recommend sow thistle as a substitute for medical treatment or pain medication.

Some traditional claims about sow thistle are particularly strong—including comparisons with powerful pain medicines—and these should be treated as folklore rather than established medical fact.

If you are considering using sow thistle medicinally, particularly if you are pregnant, breastfeeding, taking medication or managing a health condition, seek advice from an appropriately qualified health professional.

My Experience with Sow Thistle

For me, sow thistle has become one of those plants that I deliberately leave alone.

It has a season, although I seem to be able to find at least one plant somewhere in the garden throughout much of the year.

When young, the leaves are large, soft and healthy-looking—sometimes bigger than my largest dandelion leaves.

As the plant becomes older and begins flowering, the leaves become smaller and more grey-green or waxy in appearance. Even then, I still find the plant useful.

Eventually, if it is neither eaten nor removed, the plant completes its life cycle. It becomes dry and hollow, almost straw-like, and eventually breaks down in my hand.

That makes it an excellent candidate for chop-and-drop gardening.

Rather than removing the plant and carrying it away, I can simply return that organic matter to the garden.

A Plant I Choose to Keep

I consider sow thistle an important plant in my garden.

Rather than automatically pulling it out, I will often:

• Leave it growing where it isn't causing a problem
• Water around it
• Allow organic matter and manure to build the soil around it
• Harvest young leaves when appropriate
• Allow some plants to complete their life cycle
• Return mature plants to the soil as organic matter

Of course, there are times when a plant is growing where it isn't wanted. Gardening is about balance, and there is no need to allow every plant to grow everywhere.

But perhaps we could occasionally stop and ask:

“Is this really a weed—or is it a useful plant that I haven't got to know yet?”

Look Again at the “Weeds” in Your Garden

One of the wonderful things about gardening is that there is always something new to learn.

Many plants that appear spontaneously in our gardens have food, ecological or cultural value. Some provide habitat for insects, some protect bare soil, some contribute organic matter and others have been used by people for generations.

Sow thistle is one of those plants.

So before automatically reaching for the hoe, take a moment to look closely.

Identify it. Learn about it. Then decide whether it really needs to go.

For those of us who value every plant in our garden, sow thistle is certainly one worth recognising.

A Final Thought from Pam

Most of the plants I write about each month will probably never be found in a garden centre or neatly displayed for sale.

They simply appear in our gardens.

Perhaps that is part of their charm.

They are there waiting to be noticed, understood and appreciated.

So next time you see a sow thistle growing in your garden, don't be too quick to pull it out.

It may just be one of the most useful “weeds” you have.

Cheers, till next time.

Pam at The Haven