Selfheal identification and control

Selfheal Prunella vulgaris

Selfheal is a common perennial weed, found in a variety of situations, and is often abundant in lawns and managed amenity grass areas due to its ability to withstand very close mowing.

Appearance

The leaves of selfheal plants are opposite and can grow up to 50 mm long and 20 mm wide, although they are usually smaller in close-mown situations. They are generally oval shaped with prominent veins and can be light to dark green in colour, occasionally with scalloped edges.

Prunella vulgaris

Purple coloured flowers are produced between June and September and are favoured by a variety of different insects, including bees.  The flowers have two lips, the upper lip which is purple and hooded and a lower lip which is whitish and fringed.

Growth habit

An aggressive weed that will establish quickly and compete with the grass, smothering the sward if left uncontrolled. Usually spread by seed or vegetatively via short rhizomes and/or stolons. It can regenerate from fragments of shoot if the plant is disturbed.

Conditions that favour its development

Selfheal can be found on a variety of sites but is most successful in moist, nutrient rich, alkaline soil.

Cultural control

Ensure that a strong healthy grass sward is maintained, minimising the formation of gaps to prevent ingress by this aggressive weed:

• Ensure that grass plants receive adequate nutrition, applying a suitable lawn fertiliser at regular intervals throughout the growing season to create a dense, healthy sward to minimise spaces for weed invasion and to maintain competition.
• Control thatch build up with sensible watering, regular aeration and top dressing.
• Small selfheal plants can be removed hand using a knife.
• Rake/brush the sward prior to mowing to lift flowers and leaves to aid removal. Always box-off clippings to retain plant debris.
• Mow regularly and at an appropriate cutting height for the conditions to remove flower heads prior to the self-heal setting seed and to maintain good sward density.

Chemical control

Selfheal is not a difficult weed control using a selective herbicide and a single application is usually all that is required.

Spot treating individual plants before they become too widespread can be very effective.  There are a range of active ingredients with approval for the control of this weed.

Products should be applied at a time when both the grass and weed are growing strongly, usually between April and October.