Image: Ian Clarke CC BY-NC-SA 4.0
Landholder Resources

St John’s Wort

St John’s Wort (Hypericum perforatum) is a weed with bright yellow flowers and sticky fruits and seeds. Used medicinally by people, it causes illness in livestock. This plant can degrade habitat by competing with other species and increase fire risk. 

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This information is relevant across Victoria where St John’s Wort is found, particularly in north east Victoria in open woodlands. 

  • St John’s Wort spreads through suckers and seeds 
  • It thrives in disturbed areas such as those impacted by overgrazing and rabbits 
  • Seeds attach to livestock, wildlife and vehicles and can be spread by water 
  • St John’s wort can rapidly form stands that crowd out other plants 
  • Dry stem after flowering can increase fuel for fires 
  • Mites and beetles have been introduced to control St John’s Wort in Australia, however other control methods are required 
  • There are two indigenous species of St John’s Wort in Victoria that look similar to the weed. Check with an expert or your Trust for Nature manager if you are unsure 
  • Follow chemical use regulations when using herbicide 
  • Prevent spread of St John’s Wort by keeping livestock out of areas with the weed and checking vehicles and clothing after visiting sites 
  • Control rabbits and overgrazing to prevent disturbance to habitat 
  • Use an herbicide spray such as glyphosate to control most patches of St John’s Wort 
  • Spray plants during early flowering period (early spring) and before seeding (mid-summer to autumn) 
  • Small plants and small patches of St John’s Wort can be hand weeded throughout the year, however roots must be completely removed to prevent resprouting 

 

  • Monitor areas where St John’s Wort has been controlled and repeat management if needed 
  • Improving health of habitat overall and reducing disturbance will discourage St John’s Wort and other weeds 

This information is relevant across Victoria where St John’s Wort is found, particularly in north east Victoria in open woodlands. 

  • St John’s Wort spreads through suckers and seeds 
  • It thrives in disturbed areas such as those impacted by overgrazing and rabbits 
  • Seeds attach to livestock, wildlife and vehicles and can be spread by water 
  • St John’s wort can rapidly form stands that crowd out other plants 
  • Dry stem after flowering can increase fuel for fires 
  • Mites and beetles have been introduced to control St John’s Wort in Australia, however other control methods are required 
  • There are two indigenous species of St John’s Wort in Victoria that look similar to the weed. Check with an expert or your Trust for Nature manager if you are unsure 
  • Follow chemical use regulations when using herbicide 
  • Prevent spread of St John’s Wort by keeping livestock out of areas with the weed and checking vehicles and clothing after visiting sites 
  • Control rabbits and overgrazing to prevent disturbance to habitat 
  • Use an herbicide spray such as glyphosate to control most patches of St John’s Wort 
  • Spray plants during early flowering period (early spring) and before seeding (mid-summer to autumn) 
  • Small plants and small patches of St John’s Wort can be hand weeded throughout the year, however roots must be completely removed to prevent resprouting 

 

  • Monitor areas where St John’s Wort has been controlled and repeat management if needed 
  • Improving health of habitat overall and reducing disturbance will discourage St John’s Wort and other weeds 
Safety
Always wear appropriate personal protective equipment (PPE) when undertaking land management. Follow all label instructions on equipment and local regulations. Be mindful of weather conditions. Do not conduct land management on days of extreme or catastrophic fire danger or total fire ban. 
Further information
If you have a conservation covenant, please consult with your Trust for Nature regional staff member to ensure land management activities are in line with your covenant deed.

For further advice and support, please contact Trust for Nature

Phone:(03) 8361 5800
Email:  trustfornature@tfn.org.au
Disclaimer
Trust for Nature and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication