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Topped lavender (Lavandula stoechas)

Topped lavender is grown as an ornamental, but it has escaped from gardens and become a weed in disturbed places, pastures and natural ecosystems. Dense infestations can displace native plants and reduce the value of pasture, with problems reported in several Australian states.

Key facts

Type: Weed, shrub.

Native to: Mediterranean region, including southern Europe, north Africa and western Asia.

Established in: NSW, ACT, VIC, TAS, SA, WA.

Other names: Bush lavender, French lavender, Italian lavender, Spanish lavender.

Best time to act: Look for flowering plants mainly from September to January, and target regrowth with registered herbicides in spring.

Identification

  • A woody, upright, densely branched shrub, usually up to 60 cm tall but sometimes reaching 1 m.
  • Its crowded leaves are greyish or greyish-green, narrow, downy and strongly aromatic when crushed.
  • Small, deep-purple flowers form dense, compact spikes about 2–5 cm long.
  • Each flower spike is topped by up to five distinctive violet or purple leafy bracts, rarely white.
  • Look-alike: French or toothed lavender (Lavandula dentata) has finely scalloped or toothed leaf edges, while topped lavender has smooth edges.
  • Look-alike: English lavender (Lavandula angustifolia) and spike lavender (Lavandula latifolia) can be harder to distinguish; seek expert identification from a herbarium.

Where it grows

In Australia it occurs in disturbed places such as roadsides, railway lines, paddocks, poor pastures and gravel pits, and can invade grassland, woodland, dry sclerophyll forest and riparian areas.

Why it matters

  • Dense patches can exclude ground-dwelling plants and smaller shrubs, impede regeneration of overstorey plants and affect native vegetation and biodiversity.
  • It has invaded areas of conservation significance, including areas where invasive weeds threaten the rare White Beauty Spider Orchid in South Australia’s Mount Lofty Ranges.
  • Stock do not eat it, and it can out-compete pasture species, reduce carrying capacity and cause production losses.
  • Dense stands may harbour rabbits, and the plant can persist and become dominant on bare or disturbed soil.

How it spreads

  • Seeds spread by wind, water and sometimes birds or other animals, and can be carried in soil, on clothing or other objects, and in dumped garden waste.
  • Root fragments can also spread the plant, while cultivation equipment, road graders and other vehicles or machinery can drag roots and crowns to new areas.
  • It has spread in road gravel taken from infested creeks, and deliberate garden plantings have been a major source of garden escapes.

Control options

  • Hand-pull, dig out or grub individual plants and remove the main roots.
  • For large agricultural infestations, plough in spring and cultivate again when seedlings or regrowth emerge; establish a suitable pasture or other vigorous groundcover to compete with seedlings.
  • Mowing or slashing mature plants alone is not effective because they regrow from the woody base; it may help when combined with registered herbicides.
  • Controlled autumn burning can open dense infestations for follow-up control, and monitoring and control should continue for several years because the seeds can persist in soil.

Hygiene and washdown

  • Clean vehicles, machinery, boots and other gear after work in an infestation, as seeds and root fragments can be moved on clothing, equipment and vehicles.
  • Avoid moving contaminated soil or road gravel, and do not dump garden waste containing the plant.
  • Inspect and clean vehicles, plant and footwear before leaving an infested area, paying attention to tyres, radiators, belly plates, tracks and floor mats.
  • Wash down at a designated bay where runoff is contained and can be monitored for seedlings.
  • Record each washdown so the client has evidence of clean entry and exit.

Classification by state

  • Australia (national): No national listing. Managed under state and territory law.
  • Queensland: Not prohibited or restricted. Not listed as prohibited or restricted matter in Queensland. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Not a priority weed. Not a state or regional priority weed in NSW. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • Victoria: Regionally controlled / restricted weed (varies by region). Where it is regionally controlled, landowners must take all reasonable steps to prevent its growth and spread on their land. Where it is a restricted weed, trade in it (including the plant, its seed or contaminated material) is prohibited.
  • South Australia: Not declared. Not declared under the Landscape South Australia Act 2019. Other laws may still apply.
  • Western Australia: Permitted, not declared. Listed as a permitted organism in WA, so it can be brought in, but it is not a declared pest.
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Not declared. Not on the NT A to Z weed list, and Weeds Australia does not list it as declared in the NT. Check the NT declared weeds list before moving or planting it.
  • Australian Capital Territory: Not declared. Not declared under the Biosecurity Act 2023 (ACT). A general biosecurity duty still applies.

Legal obligations

Every state and territory places a duty on landholders and people working on land to prevent the spread of invasive species, such as the general biosecurity obligation in Queensland and the general biosecurity duty in New South Wales. Declarations and control requirements differ between states and local government areas, so check the current official list before work starts.

  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development
  • Australian Capital Territory: Biosecurity Act 2023 (ACT), administered by ACT Biosecurity
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • Tasmania: Biosecurity Act 2019 (Tas), administered by Biosecurity Tasmania
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA Department of Primary Industries and Regional Development

Sources