Three cornered garlic

Common Name

  • Three cornered garlic

Latin Name

  • Allium triquetrum

What’s the problem?

  • Three cornered garlic is a non-native species which is becoming increasingly widespread.
  • This species is a particular problem in the south and west of the country where conditions are generally warmer.
  • The plant spreads by seeds which are transported by ants, these germinate readily forming dense clumps which can shade out and outcompete native species.

Legal Implications?

  • Listed as a Schedule 9 species under the Wildlife and Countryside Act 1981, it is an offence to plant or allow to spread into the wild,
  • Offences under the Wildlife and Countryside Act 1981 can result in possible fines and prison sentences,
  • It is not an offence to have Three cornered garlic on your land and you do not need to notify anyone on its presence.
  • Soils containing the plant are classified as controlled waste and should be disposed of at licensed landfill.

Images supplied by Trevor Renals

In Detail

  • The plant is native to western and central Mediterranean and was originally introduced to the UK in 18th Century.
  • Spread of the plant is mainly through seed. Once established the plant forms dense clumps of growth. The white bulbs can also reproduce by vegetative propagation and can be spread by movement of soils.
  • All parts of the plant are edible and have a garlic smell.


  • A perennial herb, with white bulbs. The leaves are green, hairless and narrow with 2-5 leaves per bulb. Leaves die back once the plant has flowered around May - June.
  • Flower stems measure 10 – 45cm in height with white flowers, with a strong green stripe, similar in shape to bluebells. Stems have a triangular cross section giving rise to its common name.
  • The plant prefers shadier areas but will grow in numerous habitats.

Control Methods


  • Infestations can be removed mechanically by digging, this is easiest done in spring when surface vegetation is present, ensuring that all plant material and bulbs are removed. This may need to be followed by mechanical cutting over a number of years to exhaust the seed bank.
  • Waste materials containing the Three cornered garlic are considered ‘controlled’ waste and must be disposed of appropriately.


  • Herbicide application can by successful at reducing the spread of the plant. Applications of herbicide should be made in spring before flowering. 
  • Multiple applications may be required due to the persistence of bulbs and of the soil seed bank

When treating large areas, a suitable grass and forb mix should be sown to prevent bare ground and colonisation of other unwanted species.

If you have concerns over Three cornered garlic species on your land, if you are unsure of your legal responsibilities, or, if you would like a quotation for control, please contact one of our specialist surveyors. Treatment costs start at £380.00 + VAT.