Calamint or Lesser calamint

Scientific name: Calamintha nepeta
  • Key characteristics
  • Biology
  • Impacts
  • Control
  • Further information

  • A bushy, rhizomatous, perennial shrub up to about 50 cm tall
  • The tiny flowers are tubular, two or three-lipped, lilac to white in colour and occur in axillary spikes. They are very attractive to bees and butterflies
  • Ovate, grey-green leaves up to 2 cm long are covered in short, white hairs (especially stems, midribs and underside)
  • Leaves are very fragrant when crushed
  • Plants smell like a mixture of mint and oregano.

Origin

  • Originated around the Mediterranean, southwest Europe, and parts of Asia
  • First recorded in New Zealand in the early 1900s.

Life cycle

  • A bushy perennial plant that grows in summer and into autumn but is dormant in winter
  • It can resprout from its old woody stems or send up new stems from its rhizomatous roots.

Benefits

  • Overseas, this aromatic plant is grown as a culinary herb
  • Some useful essential oils with medicinal properties could be extracted from this species
  • Calamint is a useful garden plant, providing excellent edgings for walks, patios or herb gardens, effective when sprawled over low retaining walls or in containers and attractive in rock gardens or at the front of borders.

Occurence

  • Grows especially well in disturbed areas, old pastures, hill slopes with low rainfall and copes well with drought conditions
  • Calamint appears to be spreading on sheep and beef farms in Hawkes Bay and could perhaps become prevalent on dry, hill country farms over a much larger area of New Zealand.

Impact on pasture

  • Avoidance by grazing stock reduces pasture utilisation
  • Plants out-compete and replace desirable grasses and clovers
  • High populations in pastures can reduce overall productivity
  • Difficult to control either culturally or with herbicides.

Impact on stock

  • Unpalatable to livestock
  • Main impact on livestock is due to its reduction of area of useful pasture grasses and legumes.

  • Difficult to control once esatblished.

Prevention and early eradication

  • Be careful not to import hay from farms where the weed is prevalent and ensure contractors don’t bring it onto your farm from contaminated properties
  • Removing the first few plants that appear on the farm can pay big dividends by saving on future costs. Pulling plants out and putting them in plastic bags before burning or burying them very deeply is probably the best treatment for those first few. Take care not to spread the seed around.

Grazing management

  • Mob-stocking when seedlings are present may hinder successful establishment
  • Once established grazing will have little effect as plants are unpalatable to most classes of livestock
  • Goats may possibly browse established plants.

Mowing

  • Mowing with a torary shalsher will allow livestock better access to useful pasture species.

Pasture species/cultivars

  • Novel endophytes in ryegrass can help pastures resist weed invasion and spread. Endophytes can allow pasture species to be more drought tolerant and resistant to insect attack. This enables sown pasture species to grow more vigorously, making it more difficult for weeds to establish.

Fertiliser application

  • Ensure soil fertility levels are appropriate for good grass growth as this can increase the vigour of sown pasture species and reduce calamint establishment.

Chemical control

  • Calamint is not listed as a weedy species except in New Zealand; hence there is no information on chemical control elsewhere
  • Glyphosate as a spot treatment may burn the leaves off and could eventually lead to death of spot-treated plants
  • Dicamba or herbicides containing picloram and possibly triclopyr would be expected to offer better control. Spot treatment is advised to protect clovers and other desirable legumes.