- Small pink-flowered weeds with soft, round leaves settle into thin and bare lawn patches, then fire their seed across the grass.
- Pull or hoe young plants, rake and mow regularly in the growing season, and fill the gaps with grass so the weed has nowhere to land.
- Weedkiller is too slow, as the seed can ripen before the plant dies.
Why Spraying Loses the Race Against a Weed That Throws Its Seed
You know this plant, named or not. It makes a low, spreading mat of soft, rounded, lobed leaves, mid-green and covered in fine hairs, and it carries small pink-purple flowers. It is dove’s foot cranesbill, a low-growing annual wildflower, and the flowers look pretty and out of place in a lawn.
The fix starts with your hands. Lift small plants out by hand. Use a hand fork on bigger ones. Where a patch of them has formed, hoe it off on a warm, dry or windy day so the cut roots dry out on the surface. Then close the gap with grass seed or turf so nothing new can move in.
Skip the spray. RHS advisers say weedkillers often take days to kill this plant, and in that time the seeds can still ripen and be dispersed. A weed that fires its own seed does not wait for the chemical to finish.
What It Is and Why It Loves Your Bare Patches
This is a low-growing annual. It can reach 35cm (14in), but in a lawn it stays much shorter. Flowers appear from March to September, usually pinkish-purple in shades from strong to pale, and occasionally white. The name comes from the seed capsule, a long, narrow, pointed shape that looks like the bill of a crane.
That long flowering season is the engine of the problem. One plant produces many seeds from spring right through to early autumn. When a seed is ripe, it ejects from the pod and is catapulted away from the parent.
Where does the seed land? On the weak spots. It grows well in poor, dry soils and makes the most of patches where other plants are sparse or weak, and a thin lawn is exactly that. Light, free-draining soil suits it. It also shrugs off foot traffic and regular mowing, so a lawn that gets walked on and cut every week gives it no trouble at all.
A seedling needs light and space. Thick turf shades the soil and fills the space, and a bare patch hands both over. Lawn weeds in general are quick to colonise bare ground where grass growth is patchy.
Bare patches have ordinary causes. A summer of regular use or a spell of hot, dry weather leaves a lawn tatty, and frosty or soggy winters can take their toll, especially if you walk across the grass a lot. Each gap is a vacancy.
Pulling and Hoeing: How to Lift It With the Root
This is the good news. The root system is fibrous and grows downwards from just the centre of the plant. The roots do not creep or spread far underground. The stems and leaves spread like a mat above ground, but the whole root system sits under one central growing point. Find that point, lift it, and the plant is gone. Hand weeding is easy and satisfying.
Here is how to do it well.
1. Pull small plants by hand. Get your fingers in at the centre of the plant, not out on the trailing stems, so the root comes with it.
2. Use a hand fork on larger plants. Slide it in beside the centre, lever gently and lift the whole thing out.
3. Hoe the spread-out patches. Sever the roots of young plants on a warm, dry or windy day, so the exposed roots dry out quickly. A hoe disturbs the soil very little. Warm, dry days are rare in November, so pull or fork now and keep the hoe for spring.
4. Bag the plants and take them away. Do not leave them on the lawn.
The mistake to avoid is leaving it late. Weed before the seed ripens, as ripe seeds eject from the seedpod easily. Lift the whole plant into a bag or bucket rather than shaking it across the lawn.
Not every plant has to go. RHS advice says to let it grow in a wildflower patch, a species-rich lawn or a dry area that would otherwise be bare soil, where it adds to biodiversity. Remove it where you want to sow seed or keep a uniform, fine lawn, which is the case here.
Closing the Gaps So Nothing New Can Move In
Pulling the weed leaves a hole. A hole is an invitation. Re-seeding or re-turfing is what stops the next plant, and it is the step most people skip. Repairing bare areas helps to stop unwanted weeds colonising them, and spring and autumn are the ideal times, when the weather is damp and cool and the lawn is most likely to recover well.
The guidance gives September to November as the autumn window for sowing, and says early autumn is better as seedlings root in before the first hard frosts. November sits at the end of that window, so sow only in a mild spell. If the ground turns frosty or sodden, wait for mid-spring (March to April) and keep pulling in the meantime.
Seed is easier and cheaper when you have no spare turf. Turf gives an instant result.
To sow seed in a bare patch:
1. Cut out the damaged area in a square with a half-moon edging iron or a flat-bladed spade, then slice underneath to lift it, to a depth of about 5cm (2in).
2. Lightly fork over the soil in the square and work in some topsoil or garden compost. Firm it gently with your feet to make a level surface.
3. Scatter the seed evenly at the rate on the packet, usually about 15 to 25g per square metre (½ to ¾oz per square yard).
4. Cover the seed with a light sprinkling of topsoil or home-made compost to hide it from birds. Fleece pinned down at the edges also keeps birds off.
5. Water gently with a can fitted with a fine rose, so the seed stays where you put it.
Pick the seed to suit the cause. If shade created the bare patch, choose a seed mix for shady sites. If the lawn takes heavy wear, choose a hard-wearing utility mix. Seed takes several months to establish, and newly sown seed and fresh turf dry out until they are well rooted, so water regularly if rain is short.
For an instant fix, cut a square of healthy turf from an unseen part of the lawn, set it in the prepared square level with the grass around it, press the edges down with the back of a rake, brush a sandy top-dressing into the cracks and water it well. Your own turf avoids a patch of a different colour. The full routine is in this autumn patch repair guide.
Once the patch is repaired, find and fix the cause of the damage, so the lawn stays in good shape.
Mowing It Out in the Growing Season
Mowing is your second weapon, and it works from March to October. The advice for this plant is to mow low and often, collecting and removing the clippings. Regular close mowing prevents seed set, and any seed that does form is more likely to be carried off in the box before it can germinate.
Rake first. Drag a rake over the weedy area before you mow, to lift the stems, flowers and unripe seed heads. The mower can then cut more of the growth, which weakens each plant and stops it self-seeding. Speedwell is another creeping weed that fills thin turf, and clearing speedwell from a lawn uses a different method.
Low still means leaving some grass. Aim for 13 to 25mm (½ to 1in) in summer, and up to 40mm (1½in) in spring and autumn for an ordinary lawn, and never take off more than a third of the grass height in one cut. Avoid excessively close mowing. It weakens the grass plants, encourages shallow rooting and makes the lawn more susceptible to drought damage, weeds and moss. Extremely low cutting can also scalp the lawn and leave bare patches where there are bumps or tree roots at the surface, and bare patches are what this weed wants. Cutting too short has a second cost in hot weather, covered in mowing too short in a heatwave.
Scalping happens on soft ground when the wheels sink in, on turns taken too fast, where ruts form from cutting the same direction every time, and where the surface has bumps and hollows. Vary your direction, slow down at the turns and level the bumps.
In November the answer is different. Mowing is usually not necessary in winter unless the weather is mild and the grass is still growing. If you must, cut occasionally on a high setting, and never mow if the ground is very soft, wet or frozen. Save the close, frequent mowing for the growing season.
How to Stop It Coming Back
Thick grass is the lasting answer. A programme of spring, summer and autumn lawn care encourages dense, healthy grass growth, which makes it much harder for weeds to establish and spread.
Work through this short routine:
- Repair gaps early. Fill any bare patch as soon as you see it, in spring or autumn, before the weed gets there first.
- Never scalp. Keep the blades at the heights above and level out the bumps.
- Check the patches each spring and hoe or pull young plants early.
- Fix the cause of every bare patch. Shade, wear and drought will keep making new gaps.
On poor, dry soil that would otherwise stay bare, it feeds pollinators and adds colour. If you want a fine, even lawn, a regular look, a hand fork and a handful of seed will keep it out without a drop of spray.
