Fennel Control Guide

Do's and Don'ts of fennel control

Fennel, photo: Tim Rudman


  • Plan your control program, this will save time and money in the long-run;
  • Consider the impact of your control methods on off-target species, especially if herbicides are used;
  • Ensure machinery and equipment is washed down between sites or prior to contractors leaving site;
  • Get in early - For new infestations, eradicate before the plants reach the flowering stage: once plants begin seeding, control becomes more difficult and expensive;
  • Carefully time your use of herbicide for best results (see Herbicides for Fennel Control for more information);
  • Coordinate your control program with neighbouring landholders where your weed problem crosses property boundaries;
  • Revisit and regularly inspect the site and ensure follow-up is undertaken;
  • Use a combination of different control methods; and
  • Establish vigorous pasture (or native species) after removal to reduce re-infestation.


  • Don't introduce fennel to fennel-free areas (e.g. by failing to wash down machinery and equipment between sites);
  • Don't start your control program without first planning your approach;
  • Don't allow fennel to flower and set seed before treatment;
  • Don't rely on one attempt at removal - follow-up is essential;
  • Don't rely on just one control method.

Spread of fennel

  • Fennel is spread mainly by seed. Fennel seed falls to the ground very near the parent plant.
  • Longer-distance movement of seed occurs where seeds contaminate agricultural produce, machinery, animal skins and human clothing. Seeds are also spread in water along drainage lines.
  • Fennel can regrow from crown and root fragments. Spread occurs when crown or root fragments are moved by cultivation or earth-moving machinery.

Avoid the introduction of fennel

  • Avoid introducing fennel seed or root fragments into clean areas, or into areas from which the weed is being eradicated.
  • Implements and vehicles which have been used on infested areas should be thoroughly cleaned before leaving the site.
  • See the Washdown Guidelines for Weed and Disease Control for detailed information on how to wash-down equipment and personnel to reduce the chance of spreading fennel.

Physical removal

  • Fennel can be grubbed out, but all root material needs to be removed to stop re-sprouting from root fragments.
  • Slashing can be used before and over the flowering period to reduce fennel seeding.

Chemical control

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