Yarrow is a difficult weed to control once it is established in lawn grasses or turf so good lawn care is an effective preventative measure. First, consider whether this can be done using non-chemical means such as digging out. Where this method is not feasible, chemical controls may need to be used.
The RHS believes that avoiding pests, diseases and weeds by good practice in cultivation methods, cultivar selection, garden hygiene and encouraging or introducing natural enemies, should be the first line of control. If chemical controls are used, they should be used only in a minimal and highly targeted manner.
A number of practical approaches can be taken;
- Encourage vigorous grass growth by applying a proprietary top-dressing in early spring at 1-4kg per sq m (2-7.5lb per sq yd) working in well with a rake or broom
- Over-application may impede mowing so a trial application is advisable
- Apply a further dressing in September at a heavier rate
- Feed the grass when it is growing actively with proprietary spring and summer lawn fertilisers, taking care to follow manufacturers instructions
- During the growing season the grass should be cut regularly and lightly raked, then after two or three days, cut again, removing the long growth
- Repetition of this treatment weakens the weed and strengthens the grass
- Regular watering at seven or eight day intervals during dry periods is essential to maintain vigour in the turf
Note: Avoid feeding a lawn when it is drought-stressed.
Use of chemicals may eventually eliminate the weed. However, feeding and regular top-dressing will encourage better grass growth, and make conditions less favourable for the weed seedlings to re-establish.
Yarrow is fairly resistant to many selective weedkillers used for weed control in turf but it may be worth trying;
- Repeated applications of weedkillers containing 2,4-D, plus mecoprop-P or dicamba (Doff Complete Lawn Feed, Weed & Mosskiller, Garden Direct Lawn Feed, Weed & Mosskiller, Westland Aftercut All-in-One Feed, Weed and Moss killer (also contain fertiliser and mosskiller)) can be affective
Do not add the first lawn clippings after application of a lawn weedkiller to the compost heap. To avoid possible contamination of compost, do not collect the clippings at all but mow frequently and allow the short clippings to remain on the surface of the lawn. These will quickly disperse to leave an acceptable finish.
Weedkillers often cause severe damage if applied to lawns within six months of sowing or turf-laying.
Inclusion of a weedkiller product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener.
Weedkillers for gardeners (Adobe Acrobat pdf document outlining weedkillers available to gardeners; see sections 1b, and d)
Chemicals: using a sprayer
Chemicals: using safely and effectively
Chemicals: using spot and broad-scale weedkillers
Weeds: non-chemical control