First, consider whether this can be done using non-chemical means such as digging out or suppressing with mulch. Where these methods are not feasible, chemical controls may need to be used.
Consider non-chemical options first. Speedwell is less likely to be a problem in healthy lawns. Boost grass growth to discourage the spread of the weed by feeding with spring and summer lawn feeds. In autumn, scarify, aerate and top-dress as necessary. See our advice on autumn lawn care and spring and summer lawn care for further information.
Though the lawn should be mown regularly, do not cut it too close, as slightly longer grass will help smother the weed.
Ensure that compost containing lawn clippings contaminated with speedwell is thoroughly broken down before use.
Where speedwells occur in borders, hoe regularly, rake off the weeds and then let them dry out thoroughly before adding them to the compost heap. Alternatively, mulch the bare soil to smother the weeds. Destroy any shoots which succeed in growing through the mulch.
Always read weedkiller labels carefully before buying or using, to ensure you choose a product that is best fit for purpose. Take particular care when using residual weedkillers as these persist in the soil for several weeks or months and can move deeper or sideways in the soil, leading to possible damage of underlying plant roots.
Speedwell in established lawns
Speedwells are resistant to the majority of lawn weedkillers available to amateur gardeners. However, products containing the active ingredient fluroxypyr as one of their ingredients (Scotts Weedol Lawn Weedkiller or Weedol Lawn Weedkiller Ready to Use) will provide some control in lawns.
Speedwell in new lawns
Weedkillers often cause severe damage if applied to lawns within six months of sowing or turf-laying. Materials containing fluroxypyr as one of their ingredients, however, are claimed to be safe to use after only two months.
Speedwell in beds and borders
Spot treat using the non-selective weedkiller glyphosate*, taking care to avoid all contact with cultivated plants. Glyphosate is most effective between June and September. Use the gel (Scotts Roundup Gel) or ready-to-use spray (e.g Scotts Fast Action Roundup Ready-to-Use, Bayer Garden Rootkill Weedkiller, Doff Glyphosate Weedkiller Ready-to-Use) on patches of speedwell. Leave the weed for three to four weeks for the weedkiller to take effect, before removing dead foliage.
*A note on glyphosate May 2016: After reviewing glyphosate, the European Parliament has given the go ahead to relicense it but proposes disallowing certain uses such as public open space and restricting it to professional use only. The final resolution will be decided by national authorities this summer which may mean the withdrawal of glyphosate-based weedkillers for home gardeners in the UK. Check the RHS website for further updates.
Weedkillers for gardeners (Adobe Acrobat pdf document outlining weedkillers available to gardeners; see sections 1b and 4)
Chemicals: using a sprayer
Chemicals: using safely and effectively
Chemicals: using spot and broad-scale weedkillers
Weeds: non-chemical control