The short answer
Weeds in artificial grass come from two directions, and you deal with each differently. Growth from below (roots pushing up through the lawn) is prevented at installation by a weed membrane over the soil and a clean, compacted base; if persistent perennial weeds are the issue, removing them and using a sound membrane is the real fix. Weeds from above are far more common once a lawn is down — airborne seeds land in the sand infill or in trapped organic debris and root shallowly. These are easy to deal with: pull them out by hand, keep the lawn clear of leaf litter that gives seeds something to root in, and treat stubborn patches with a grass-safe weed treatment. Regular brushing and rinsing stop debris building up, which is the main thing that lets surface weeds get established.
People are often surprised to find weeds in an artificial lawn. The good news is that most appear on the surface, not from underneath, so they're shallow-rooted and simple to remove — and easy to prevent with a little routine care.
Weeds and artificial grass
- From belowPrevented by weed membrane
- From above (common)Airborne seeds in infill/debris
- Surface weedsShallow-rooted, easy to pull
- Key preventionKeep lawn clear of debris
- Stubborn patchesGrass-safe weed treatment
Why weeds appear at all
It seems odd that a plastic lawn grows weeds, but there are two sources:
- From below: if perennial weeds or their roots were left in the ground, or the base lacks a proper membrane, growth can push up through the drainage holes and seams. This is the harder type to deal with after the event, which is why prevention at installation matters.
- From above (the common one): windblown seeds settle on the lawn, lodge in the sand infill or in any layer of rotting leaves and dust, and germinate with shallow roots. Because they're rooting in surface debris rather than soil, they come away easily.
Most weeds in an established artificial lawn are the second type. They're a sign that debris has been allowed to build up, not that the lawn has failed.
Preventing weeds from below at installation
The defence against weeds growing up through the lawn is built in when it's laid:
- Clear the ground first: remove existing weeds, especially tough perennials, before basing. Roots left in place can persist.
- Weed membrane: a geotextile membrane over the soil suppresses growth from below while still letting water drain. Many installers add a second membrane above the levelling layer for extra protection directly under the grass.
- Compacted base: a properly built Type 1 sub-base and levelling layer leave little for roots to exploit.
If you already have weeds coming up from below an existing lawn, it usually points to a missing or failed membrane or roots left in the ground. Spot-treating with a suitable weed treatment can help, but a lasting fix may mean lifting the affected area, dealing with the roots and re-laying with a sound membrane.
| Weed source | Prevention / fix | When |
|---|---|---|
| From below (roots) | Clear weeds + weed membrane | At installation |
| From below (existing lawn) | Treat, or lift and re-membrane | Ongoing / remedial |
| From above (seeds) | Pull out, clear debris | Routine upkeep |
| Stubborn surface weeds | Grass-safe treatment | As needed |
Indicative approaches. Match the method to the source.
Dealing with surface weeds and keeping them away
For the common, shallow-rooted surface weeds, treatment is straightforward:
- Pull them by hand: because they root in the infill or debris, most lift out cleanly. Do it while they're small.
- Keep the lawn clear: regularly remove fallen leaves, blossom and other organic debris before it rots into a layer that seeds can root in. This is the single most effective prevention.
- Brush and rinse: routine brushing and an occasional hose-down stop debris building up and keep the infill clean.
- Treat stubborn patches: for weeds that keep returning, use a weed treatment that is safe for artificial grass, following the instructions and rinsing afterwards. Avoid harsh products meant for other surfaces unless confirmed grass-safe.
With a clean lawn and prompt removal of any seedlings, surface weeds rarely become more than an occasional, minor job. The key is not letting organic debris accumulate, since that's what turns a clean infill into a seedbed.
Dealing with moss, edges and seams
Alongside true weeds, a couple of related problems crop up on artificial lawns, and they respond to similar thinking — keep the surface clean and the lawn dealing with them is straightforward.
Moss and algae are not weeds in the usual sense, but they colonise damp, shaded artificial grass in the same way they would paving. They take hold where debris and moisture linger, typically in north-facing or tree-shaded corners. To manage them: clear the organic debris that feeds them, improve airflow and light where you can by trimming back overhanging growth, and treat affected areas with a product that is safe for artificial grass rather than a harsh paving moss killer that could damage the fibres. Regular brushing and rinsing in shady spots stops them establishing in the first place.
Edges and seams deserve a special mention, because they are the places weeds most often appear even on a well-membraned lawn. Wind-blown soil and debris collect against borders and walls, creating a little pocket where seeds can root, and any gap at a seam gives growth a route through. Keeping the perimeter clean, making sure edges are properly secured, and checking seams are sound all reduce these opportunities. A quick inspection of the edges when you brush the lawn catches seedlings while they are still easy to pull.
The overall picture is reassuring: artificial grass dramatically cuts the weeding a real lawn demands, and the weeds that do appear are mostly shallow surface growth that lifts out by hand. The membrane and a clean base handle the harder problem of growth from below, while a light routine of debris clearing, brushing and the occasional grass-safe treatment keeps the surface clear. There is no digging, no persistent perennial roots to battle, and no need for the repeated chemical treatments a paved or gravelled area might need — just the odd few minutes of upkeep.
Frequently asked questions
Does artificial grass stop weeds growing?
It greatly reduces them but does not stop them entirely. A weed membrane and a clean compacted base prevent most growth from below, but windblown seeds can still root in the sand infill or in trapped organic debris on the surface. These surface weeds are shallow-rooted and easy to pull out, and good upkeep keeps them to a minimum.
Can you use weed killer on artificial grass?
You can use a weed treatment that is specifically safe for artificial grass, following the instructions and rinsing afterwards. Avoid strong weed killers intended for paths or paving unless they are confirmed grass-safe, as some can damage or discolour the fibres. For shallow surface weeds, hand-pulling is often all that's needed.
Why are weeds growing through my artificial grass?
If weeds push up through the lawn or seams, it usually means the weed membrane is missing, damaged, or perennial roots were left in the ground before laying. Weeds appearing on the surface instead are airborne seeds rooting in the infill or debris. Identifying which it is tells you whether to treat the surface or address the base.
Sources & further reading
Figures on this page are typical UK ranges drawn from published cost guides and are intended as guidance, not a quotation.