How to Get Rid of Thistles

Thistles are among the most troublesome weeds of UK gardens, lawns and paddocks. The two you are most likely to meet are spear thistle (Cirsium vulgare), a biennial that grows a vicious rosette in…

Thistles are among the most troublesome weeds of UK gardens, lawns and paddocks. The two you are most likely to meet are spear thistle (Cirsium vulgare), a biennial that grows a vicious rosette in its first year and flowers in its second, and creeping thistle (Cirsium arvense), a perennial that spreads by deep, brittle, creeping roots as well as by wind-blown seed. Both are listed under the Weeds Act 1959, but that does not make their presence in a garden automatically unlawful. A specific legal obligation to control them arises if an appropriate official order is served. This guide covers controlling both.

How to identify it

Spear thistle forms a large rosette of deeply lobed, extremely spiny leaves, then a tall branched stem topped with large purple flower heads on spiny bases. Creeping thistle is shorter and patch-forming, with smaller lilac-purple flowers and softer, spiny leaves, spreading underground to throw up colonies of shoots. Both produce fluffy, parachute-borne seed that drifts widely on the wind.

How to get rid of thistles

Dig out spear thistle. Because it is a biennial with a single taproot, spear thistle is best dug out in its first-year rosette stage — lever out the crown and taproot with a fork before it ever flowers. Wear thick gloves.

Exhaust creeping thistle. The perennial creeping thistle regrows from root fragments, so digging alone tends to multiply it. The organic approach is repeated cutting or hoeing: remove every shoot as it appears through the season so the plant cannot photosynthesise, and with sustained control over successive growing seasons the root reserves are exhausted. Patience is essential.

Cut before it seeds. Whichever species, cut the flower stems at the bud or early-flower stage before the fluffy seed forms. This is the single most important step for stopping spread, as a mature head releases hundreds of wind-borne seeds.

Weedkiller. For small garden outbreaks, the RHS recommends non-chemical methods: remove spear-thistle rosettes before flowering, hoe creeping-thistle seedlings while young and repeatedly pull or cut new shoots from established creeping patches. Avoid cutting roots into fragments that could spread the weed. Maintain a vigorous lawn or well-covered border to reduce re-establishment.

Stopping it coming back

Keep on top of seedlings and never let plants flower and seed. Maintain a dense lawn or border planting, and watch boundaries with rough ground and paddocks, which are the usual source of wind-blown seed. For creeping thistle, ongoing vigilance is needed because a single missed root fragment can restart a colony.

When to call a professional

A large creeping-thistle infestation across a paddock or reclaimed plot may justify a contractor with a programme of topping and treatment — and given the legal duty to prevent spread, persistent infestations near agricultural land are worth dealing with promptly.

COMPARE & EXPLORE

Other garden problems to look out for

Different problems can produce similar-looking symptoms. These related guides may help narrow down what you are seeing.

Weeds · Related guide How to Get Rid of Broadleaf DockView guide → Weeds · Related guide How to Get Rid of BurdockView guide → Weeds · Related guide How to Get Rid of BramblesView guide →

Return to the Plant Problems finder →