Speedwell Is Tough — But So Is a Healthy Lawn
Speedwell resists most weedkillers, so your best defence is thick, competitive grass. Our seasonal treatments strengthen your lawn while targeting broadleaf weeds — the combination that actually works.
Let’s be honest from the start: speedwell is one of the most difficult common UK lawn weeds to control. If you’ve already tried treating it and watched it bounce back, you’re not doing anything wrong – this weed genuinely is that stubborn.
The chemical that used to kill speedwell effectively (Ioxynil) was banned in 2015. Since then, gardeners and professionals alike have been fighting an uphill battle. But difficult doesn’t mean impossible. Understanding what you’re dealing with – and what actually works – puts you in the best position to win.
What Is Speedwell?
Speedwell belongs to the Veronica genus, and you’ll encounter three main types in UK lawns: slender speedwell (Veronica filiformis), germander speedwell (Veronica chamaedrys), and thyme-leaved speedwell (Veronica serpyllifolia). All produce those distinctive flowers with four petals – though the colour varies from bright blue to pale blue-white depending on species.
The key thing to understand is that speedwell is perennial. Unlike annual weeds that die off and regrow from seed, speedwell’s root system survives year after year. Kill the leaves and stems, and it simply regrows from the roots. This is why it’s so persistent.
All types spread by creeping stems that root at intervals wherever they touch soil. They grow flat to the ground, ducking under mower blades, and can form dense mats that smother grass. Worse still, every fragment of stem that breaks off during mowing or raking can root and grow into a new plant.
Identifying Speedwell Varieties
You don’t strictly need to identify which type you have – the control methods are the same – but knowing what you’re dealing with helps you understand the problem.
Slender Speedwell (Veronica filiformis)
The most common lawn speedwell. Has tiny, rounded leaves (5-10mm) on thread-like stems. Flowers are small (8-10mm), pale blue with darker veins, appearing March to May. Originally introduced as a rock garden plant from Turkey before escaping into lawns across the country. It rarely produces viable seed in the UK, spreading almost entirely by stem fragments – which is why mowing spreads it so effectively.
Germander Speedwell (Veronica chamaedrys)
Coarser than slender speedwell, with larger triangular leaves (1-3cm) that have toothed edges and two distinct lines of fine hairs on the stems. Flowers are bigger (10-12mm) and a deeper, brighter blue with a white centre, appearing March to August. Can grow up to 50cm tall in borders but stays low in mowed lawns. Unlike slender speedwell, it spreads by seed as well as stem fragments, making it potentially harder to eliminate.
Thyme-Leaved Speedwell (Veronica serpyllifolia)
Often overlooked because its flowers are smaller and paler. Has oval, glossy leaves (1-2cm) that resemble thyme, arranged in opposite pairs along creeping stems. Flowers are tiny (5-8mm), pale blue to white with darker veins, appearing April to October. Thrives in damp, shaded lawns and compacted areas. Spreads by both seed and rooting stems, and tolerates close mowing better than other speedwells.
Quick Comparison: UK Lawn Speedwells
Speedwell often appears alongside other low-growing lawn weeds like trefoil and chickweed, all exploiting similar gaps in the turf.
Why Is Speedwell So Hard to Kill?
Several factors combine to make speedwell particularly resistant:
It resists most weedkillers. The leaves have a waxy coating and fine hairs that prevent herbicides from penetrating effectively. Products that kill clover and dandelions often barely touch speedwell.
The best chemical was banned. Ioxynil was highly effective against speedwell, but EU regulations removed it from sale in 2015. Nothing currently available works as well. The best remaining option is fluroxypyr, but even this typically requires multiple applications.
It’s perennial with a strong root system. The plant stores energy in its roots, so it can regrow repeatedly even when the foliage is killed. You’re not just fighting what you can see.
It spreads by fragments. Every time you mow, rake, or scarify, you risk breaking stem pieces that then root elsewhere. Without realising it, you might be spreading speedwell around your lawn.
It thrives in good conditions. Unlike many weeds that indicate poor soil, speedwell actually loves moist, nutrient-rich ground. Your well-watered, well-fed lawn might be exactly what it wants.
What Actually Works Against Speedwell
Controlling speedwell requires a multi-pronged approach. No single method will eliminate it, but combining several tactics gives you the best chance.
1. Box Your Clippings – This Is Crucial
If you do nothing else, start collecting your grass clippings instead of mulching them back in. Every time you mow without boxing, you’re potentially spreading speedwell fragments across your lawn. Those fragments root within days.
The same applies to raking and scarifying – remove all debris from the lawn and don’t compost it (unless your compost gets hot enough to kill plant material). Treat any speedwell-contaminated material as waste.
2. Hand Removal for Small Patches
If speedwell has only appeared in a few spots, dig it out completely. Use a spade to remove the entire patch plus a good margin of surrounding soil – speedwell stems can extend further than you’d expect. Reseed the bare patch promptly to prevent recolonisation.
Be thorough. Any stem fragment left behind will regrow. After removal, watch the area closely for several weeks and dig out any regrowth immediately.
3. Selective Weedkiller (Multiple Applications)
For larger infestations, you’ll need a selective lawn weedkiller containing fluroxypyr. This is the most effective ingredient still available, though it’s nowhere near as good as the banned Ioxynil. Products containing 2,4-D or dicamba can help weaken speedwell when used alongside fluroxypyr.
Apply when speedwell is actively growing (spring is ideal) and expect to treat again after 6-8 weeks. Many cases need three or four applications over a season to see real results. The weed often looks unaffected for weeks before suddenly declining – patience is essential.
Some professionals report better results by applying lawn sand (ferrous sulphate) first to burn back the leaves, then following up with weedkiller once fresh growth appears. The new leaves are more vulnerable than the older, tougher foliage. For borders where speedwell has escaped, glyphosate offers a non-selective option that kills everything.
4. Build a Competitive Lawn
Thick, healthy grass leaves no room for speedwell to spread. This won’t kill existing plants, but it prevents the weed from expanding and makes your other control efforts more effective.
Feed your lawn seasonally to promote dense growth. Water deeply but infrequently to encourage deep grass roots. Aerate compacted areas to improve grass vigour. Overseed any thin patches before speedwell colonises them.
Raise your mowing height slightly – taller grass shades the soil surface and makes it harder for speedwell stems to root successfully.
5. Rake Before Mowing
Running a spring-tine rake over speedwell patches before mowing lifts the creeping stems into an upright position. The mower then catches more of the plant, weakening it over time. Combined with boxing clippings, this gradually depletes the weed’s energy reserves.
Setting Realistic Expectations
Complete eradication of established speedwell is difficult. Many gardeners find that consistent control – keeping it suppressed rather than eliminated – is a more achievable goal.
The good news is that with persistent effort, you can reduce speedwell to the point where it’s barely noticeable. A thick lawn hides a lot, and regular treatment prevents the dense mats that really spoil the appearance of your grass.
Think of it as an ongoing management task rather than a one-time fix. Treat in spring, box your clippings all season, hand-pull any obvious patches, and maintain strong grass growth. Over two or three seasons, most people see dramatic improvement even if a few plants persist.
Frequently Asked Questions
Why is speedwell so hard to kill?
Several factors: it’s perennial (regrows from roots year after year), the leaves resist herbicide penetration, and the most effective chemical (Ioxynil) was banned in 2015. It also spreads via stem fragments, so mowing and raking can accidentally spread it around your lawn. Current weedkillers work, but typically need multiple applications.
What are the different types of speedwell in UK lawns?
Three main types: slender speedwell (tiny rounded leaves, pale blue flowers, spreads only by fragments), germander speedwell (larger triangular toothed leaves, bright blue flowers, spreads by seed and stems), and thyme-leaved speedwell (oval glossy leaves, pale blue-white flowers, prefers damp shade). Control methods are the same for all three.
Will mowing get rid of speedwell?
No – speedwell grows flat to avoid mower blades. Worse, mowing can actually spread it by breaking stems into fragments that root elsewhere. If you have speedwell, always box your clippings rather than mulching. Raking before mowing helps lift stems into the blade path, which weakens the plant over time.
Can I dig out speedwell by hand?
For small patches, yes – but you must be thorough. Remove the entire plant plus surrounding soil, as stems spread underground. Any fragment left behind will regrow. Watch the area for weeks afterwards and remove any regrowth immediately. Reseed bare patches quickly to prevent recolonisation.
What time of year should I treat speedwell?
Spring is best, when speedwell is actively growing and absorbs weedkiller most effectively. Expect to need repeat treatments – typically 2-4 applications over the season, spaced 6-8 weeks apart. Autumn treatment can also help catch any late-season growth before winter.
Does speedwell mean my lawn is unhealthy?
Not necessarily. Unlike clover or trefoil (which indicate low nitrogen), speedwell actually thrives in moist, nutrient-rich soil – the same conditions grass likes. Speedwell often gets established through contaminated compost, soil, or turf, then spreads from there. A healthy lawn resists its spread better, but won’t prevent it appearing in the first place.
The Bottom Line
Speedwell is genuinely one of the toughest lawn weeds you’ll face. Anyone who tells you it’s easy to kill either hasn’t dealt with it or is selling something.
But difficult isn’t impossible. Box your clippings religiously, treat with fluroxypyr-based products multiple times per season, hand-remove small patches before they spread, and maintain the thickest lawn you can. Most people who stick with this approach see major improvement within a couple of seasons.
The key is persistence. Speedwell didn’t take over your lawn overnight, and it won’t disappear overnight either. Consistent effort wins this battle. For more weed control strategies and lawn care tips, explore our UK lawn care guide hub.
Build a Lawn That Fights Back
Our Spring Lawn Treatment strengthens your grass while targeting broadleaf weeds. A thick, well-fed lawn is your best long-term weapon against speedwell.
