Creeping thistle

How to recognise it

Habit

Perennial, 30–120 cm tall, forming large patches with creeping roots. Each stem is much branched at the top.

Leaf

Oblong, wavy and lobed, with spiny edges; hairless above, sometimes slightly woolly below. The leaf does not run down the stem.

Stem

Without wings and without spines: that is how you tell it from most other thistles.

Flower

In June–September many small, lilac to pale purple heads of 1.5–2.5 cm, sweetly scented. Male and female flowers are usually on separate plants.

Fruit

A small nut with a white, feathery pappus that comes off easily.

Roots

Long, horizontal roots that also go deep into the soil and keep producing new shoots.

Confused with

Marsh thistle and spear thistle have spiny-winged stems, are biennial and have no creeping roots. Marsh thistle has smaller, dark purple heads in clusters; spear thistle has larger, egg-shaped heads.

Flowering: June–September · Pruning: June and August

Why grow it?

• One of the best nectar plants of summer: peacock, small tortoiseshell, painted lady and whites, as well as bees, bumblebees and hoverflies, all come to it.
• Food plant: painted lady caterpillars eat the leaves, and many beetles, bugs and small flies live on or in the plant.
• Goldfinches and other seed-eaters eat the seed, and the down is sometimes used to line nests.
• The lilac heads smell sweet, a little like honey.
• A tough pioneer that quickly covers bare, disturbed ground.

Creeping thistle: where does it grow best?

• In the wild: fields, pastures, verges, waste land, rough ground, woodland clearings, dykes and building sites.
• Full sun to light partial shade.
• Almost any soil, preferably deep, loose and rich; on poor, dry soil it stays smaller.
• In the garden: only in a wild corner or rough patch that you can mow all round, well away from the vegetable plot and borders.

Goes well with

• Common nettle: Together a rich butterfly patch: nettle for the caterpillars, thistle for the nectar.
• Tansy: Yellow buttons in late summer in the same rough patch.
• Wild teasel: Another seed plant for goldfinches in the wild corner.
• Wild carrot: White umbels for hoverflies and beetles.

Creeping thistle: when and how to plant it?

1. Better not to plant creeping thistle on purpose: it often arrives by itself and is hard to get rid of. Never take plants or roots from the wild or from someone else’s land either.
2. If it appears in a wild corner, let it stay if that spot is surrounded by lawn or a path that you mow regularly.
3. A root barrier helps little, as the roots go deep. Mowing around it works better.
4. Sowing is not needed: new plants mainly grow from root pieces, and seed only germinates on bare ground.
5. Keep it out of the vegetable garden, out of perennial borders and away from nearby fields and pastures.

Care

Water

Not needed.

Feeding

Not needed: it grows most strongly on rich, disturbed soil.

Weakening by mowing

Mow or cut the stems when they are in bud, in June, and again in August. The plant then uses up its reserves and the roots weaken. Repeat for a few years.

Do not dig

Do not dig or rotavate: every root piece of a few centimetres can become a new plant. Pull or dig out stems preferably after rain, with as much root as possible.

Competition

Dense turf or rough vegetation with other plants keeps it in check better than bare soil.

Seed

Cut off the flower heads before they turn fluffy if there are fields or pastures nearby.

Tip: To weaken creeping thistle, mow at the right time: when the buds appear in June and again in August. That weakens the roots far more than digging, which actually helps the thistle spread.

Pruning and mowing

Pruning months: June and August.

When: In June, when the buds appear, and again in August.

How:

• To weaken it: mow or cut the stems just above the ground when the buds appear.
• Repeat every time it grows back; after a few years the patch becomes weaker.
• In a wild corner: let it flower for butterflies and bees, and cut off the heads before they turn fluffy.
• In autumn, leave a few dead stems standing until spring as shelter for insects.

Caution: Wear sturdy gloves: the leaves are spiny.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Roots

It spreads mainly by creeping roots; every piece can grow into a new plant. So do not move soil containing root pieces.

Seed

Only pollinated female plants produce seed with down. The down often detaches from the seed, so much of the seed stays close to the plant.

Creeping thistle: how does it get through the winter?

Hardy to −30 °C.

• The stems above ground die off; the plant overwinters with its deep roots.
• Fully hardy. From March–April new shoots come up from the roots.
• Dead stems give shelter to insects, and birds search them for the last seeds.

Diseases and pests

• Spreading: The biggest challenge. Repeated mowing in June and August, pulling after rain and dense vegetation work best.
• Aphids: Often in colonies on the stems, with ants in attendance. Ladybirds and hoverfly larvae clear them up; do nothing.
• Thistle rust: A rust fungus makes some shoots pale and stunted, with rusty brown spores on the leaves. It weakens the thistle, so there is no need to act.
• Neighbours: Farmers do not want it in their fields and pastures. Cut off the flower heads before they turn fluffy and keep the edges of your garden mown.

Through the year

• March: New shoots appear from the roots.
• April: Pull young shoots if you want to weaken it.
• June: Buds and first flowers. To weaken it: mow at the bud stage.
• July: Full flower; butterflies, bees and hoverflies on the flowers.
• August: Seed ripens; goldfinches visit. Second cut to weaken it.
• September: Last flowers. Cut off heads before they turn fluffy.
• November: Dead above ground; leave the dry stems for insects.

Did you know?

• In North America it is called ‘Canada thistle’, even though it comes from Europe and Asia and was brought there by settlers.
• The small fly Urophora cardui lays its eggs in the stem; a thick, egg-shaped gall grows there, in which the larvae live.
• Creeping thistle is dioecious: a plant usually bears only male or only female flowers. A large patch is often a single clone of one sex.