Spear thistle (Cirsium vulgare), also known as bull thistle, common thistle, and scotch thistle, is a significant concern for UK farmers and landowners. Whilst people associate the thistle with the Scottish national identity, its invasive nature also causes land management issues. Legislation states that It must not be allowed to spread to neighbouring land. Early spear thistle identification is extremely beneficial, allowing the implementation of control measures before the plant reaches a significant size. Here, we will guide you to a better understanding of the plant, explain whether spear thistle is a weed and its legal status in the UK. We will also discuss the problems it causes, the best methods for getting rid of spear thistle and identification. Effectively dealing with the plant depends on spotting it early and the selection of the most appropriate control method for your situation.


Spear thistle is a valuable source of nectar for bees and butterflies. Smaller birds, such as goldfinches and linnets, also feed on spear thistle seeds where it is an important source of food. However, whilst spear thistle plays a valuable part in our natural ecosystem, it’s prickly presence is far less welcome for farmers, gardeners and landowners. Highlighting the need for early spear thistle identifiction and removal.

Close up of a bee gathering nectar from a spear thistle flower

Close up of a bee gathering nectar from a spear thistle flower


Is spear thistle a weed?

Spear thistle is a weed. A weed is often defined as a plant variety that has spread in an area where it is not wanted. However, spear thistle is also one of the five plants listed under the Weeds Act 1959 as an ‘injurious weed’. Others listed in the Act: common ragwort, curled and broad-leaved dock, creeping thistle and spear thistle. This legislation has been at the centre of weed control in the UK for decades. It classifies those plants that are native to the UK, but ultimately deemed harmful to agricultural land.


Is spear thistle illegal in the UK?

Spear thistle is not illegal in the UK. However, because Cirsium vulgae is classified as an injurious weed, according to legislation, it does mean that there are legal restrictions realted to its growth that must be considered. The Weeds Act 1959 gives the authorities power to enforce landowners to prevent the spread of spear thistle to neighbouring land.  In practice, landowners, farmers and property owners may need to consider spear thistle removal to avoid prosecution, as well as limiting the impact to their own land.


Why is Spear thistle a problem?

The problems related to the plant are not only concerned with its injurious weed status, but also because spear thistle removal can prove difficult. A single plant can grow to quite a scale, as can be seen below. And, an infestation will be persistent, partly down to the very deep tap root that can anchor itself into the ground, even in the first year.

The weed also can spread very quicky. Spear thistle seeds have silky pappus hairs which are designed to be carried effectively by the wind. A single Spear thistle seed head can produce about 100 seeds which once airborne mostly fall within the first 40m, however can still potentially reach a neighbouring field or property. Most of the seeds are eaten by wildlife, mainly small birds, but they can also remain in the soil for up to three years.

Once a spear thistle infestation establishes itself it can cause real damage to agricultural land by dominating other plant species and reducing the quality of crops as well as grazing land. Livestock will generally try to avoid spear thistle because it is so sharp and prickly, but if ingested by an animal it can also cause painful injury and result in a call to the vet.

The tap root of a small spear thistle plant. Demonstrating that removal of the plant's tap root is an effective way to get rid of spear thistle over a small area.

The tap root of a small spear thistle plant


Spear thistle identification

There are multiple species of thistle in the UK, and it’s not always easy to tell them apart. Spear thistle identification is aided by a number of lifecycle characteristics. The weed is a biannual plant and grows up to metre and a half tall, sometimes higher in latter years. Scottish thistle plants usually reach their highest point in their second year. Multiple spiny wings grow out along each stem.

Key spear thistle identification features include:

  • Flowers: Pink or purple florets arranged in a clustered flowerhead atop a spiny yellow bract.
  • Leaves: Greyish-green, lobed, and spine-shaped, resembling a spear. The leaves are rough with hairs on the upper side.
  • Growth Pattern: The plant is biennial, reaching its maximum height in its second year.
Close up of the downy leaves of spear thistle (Cirsium vulgare)

Close up of the downy leaves of spear thistle (Cirsium vulgare)

Spear thistle flowers appear in the summer months from July and can persist as late as October. The flowers consist of pink or purple florets arranged as a clustered flowerhead with a flat top which is between 2 and 5cm in diameter. This sits atop the distinctive spiny ball (the bract) which is yellow in appearance and gives the plant its ‘classic’ thistle appearance.

Plant structure

The stem grows out of the spear thistle rosette at the base of the plant. The rosette consists of a number of basal leaves that can be up to 30 centimetres in length. The greyish-green spear thistle leaves are lobed and spine-shaped like a spear, giving the plant its name. The leaves feel rough with hairs on the upper side. There are further smaller spiny, spear-shaped leaves along the stem.

Spear thistle (Cirsium vulgare) should not be confused with cotton thistle (Onopordum acanthium), which confusingly is also known as ‘scotch’ or ‘scottish thistle’. Cotton thistle is not actually a native UK species. However, it has the potential to be an equally damaging and persistent nuisance as spear thistle.


Where is Spear thistle found in the UK?

Spear thistle is a native species that is extremely common all over the UK – it’s not just found in Scotland! A typical spear thistle habitat is the perimeter of fields and verges of roads, but it is also often found on wasteland. You’ll also find it in gardens, most likely as an unwelcome weed. The plant is also very common outside the UK and is native throughout most of Europe. It is also commonly found in North America, Africa, and Australia.


How to get rid of Spear thistle

In considering how to get rid of Spear thistle, there are a number of options depending on the extent and stage of the infestation. It is possible to cut the Spear thistle back each year and the tap root can be severed. This can weaken an infestation. Good agricultural practices are also amongst the methods of control at the disposal of land managers and plant removal specialists.

  1. Cultural Control:
    Annual cutting back and severing the tap root can weaken the infestation. Additionally, maintaining good agricultural practices, such as avoiding overgrazing and keeping the soil healthy, can reduce the chances of spear thistle establishing itself.
  2. Chemical Control:
    Herbicide treatment often needs to be considered for severe infestations. These pesticdes are typically applied in the spring and summer months during the plant’s growth period. Sometimes, a multi-year treatment plan may be required to completely eradicate the weed.
  3. Mechanical Control:
    Physical removal of the plants, particularly targeting the deep tap roots, can be effective but requires effort and persistence.

A multi-year approach is usually required, as a tenacious infestation of spear thistle can return, even if properly treated.

Close up of spear thistle leaves and flowers

Close up of spear thistle leaves and flowers

Successfully removing a scotch thistle plant needs someone with the appropraite skills and training to apply the required treatment. Always refer to HSE guidance for the proper and safe use of herbicides.

If you use pesticides in your garden, allotment, or on houseplants you are legally responsible for using them correctly and effectively. You must keep your garden and allotment safe for people, pets and wildlife.

When seaking assistance, always ensure that you engage with professionals who have a strong track record of dealing with invasive and injurious weeds.

At PBA Solutions, we deal with a wide range of injurious weeds and invasive plant species. We are always happy to offer spear thistle identification assistance, and advice on the best solutions to prevent its spread. If you are concerned with how to get rid of spear thistle, or require assistance with its control, call 0203 174 2187 or 01202 816134 to talk to one of our consultants today.


Lead image: Close up of spear thistle flowers and leaves
All pictures © tintac



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