Speedwells (Veronica spp.) are pretty, blue-flowered perennials that look attractive in a flower-rich lawn. However, their ability to root quickly, even from small sections, means they can quickly get out of hand in both lawns and borders.
Botanical names Veronica spp.
Areas affected Lawns and borders
Timing Flowers from early spring onwards; treat lawns in spring-autumn, treat borders in early summer-early autumn
What is speedwell?
Slender speedwell (Veronica filiformis) was introduced to Britain from Turkey and the Caucasus during the early 19th century. It was much grown as a rock plant until gardeners realised how invasive it could be. It is now widely naturalised in many parts of the country and can be a cheerful addition to a flower-rich lawn. Learn more about making the most of lawns as a wildlife habitat and ways to help our bees;
Slender speedwell along with several other species of speedwell are invasive and can be a weed in lawns and borders. This page looks at options where speedwell is becoming a problem.
Slender speedwell (Veronica filiformis) is a low-growing plant with bright blue, long-stemmed flowers early in the year, usually March to May. It is low-growing and can form dense patches in a lawn.
Germander speedwell (Veronica chamaedrys) is a stronger growing, coarser species than V. filiformis, flowering March to August. It is native in grassland, open woodland and hedgerows throughout the British Isles. It is usually troublesome in less frequently mown grass but can adapt to, and survive under, close mowing.
Ivy-leaved speedwell (Veronica hederifolia) and thyme-leaved speedwell (Veronica serpyllifolia) are occasionally troublesome in lawns or borders, the former favouring shadier situations, the latter moister conditions.
Why is speedwell a problem?
Speedwells are perennial plants, producing numerous, slender-branched stems, creeping and rooting at the nodes as they spread to form a dense weed carpet.
The flowers are rarely followed by seeds as the plants are self-sterile and most appear to be from the same clone.
The commonest methods of spread include:
- Stem sections scattered by the mower
- Lawn clippings put on the compost heap, which spread the weed around the garden if the compost is spread before it is completely decomposed
- Nesting birds can spread speedwell while gathering moss from the lawn to line their nests
- Weak grass growth allows the weed to spread
Even when lawn clippings are raked up and disposed of, or the lawn is raked thoroughly to remove moss and weeds, numerous small rooted sections of the weed usually remain.
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.
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.
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 (Weedol Lawn Weedkiller or Weedol Gun 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.
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.
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 (Roundup Gel) or ready-to-use spray (e.g Roundup Fast Action Ready-to-Use, SBM Job done General Purpose Weedkiller, Doff Advanced 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.
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 4)
The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.