Can you use weedkiller on artificial grass?

By The Weed Guy·Last updated 2 September 2026

Yes, and plain glyphosate is the one to reach for. Glyphosate kills a plant by blocking an enzyme that only plants have, so there is nothing in it that can attack polyethylene fibres or a latex-backed turf. The things that genuinely wreck artificial grass are the cheap alternatives people try first: bleach, salt, boiling water and anything petroleum based. Spot-spray the weed itself, keep it off the rest of the pile, and read your turf warranty before you start, because plenty of them exclude chemical damage.

The mechanism is the part that actually answers this, so here it is. Glyphosate works by blocking an enzyme called EPSP synthase, which sits in a chemical pathway that plants and some microbes have and animals do not. What goes in the sprayer is that active as a water-soluble salt, in water, with a wetting agent. It is not an acid, not a bleach and not a solvent, so there is no process by which it goes to work on a plastic. Your grass fibres are polyethylene or polypropylene, the primary backing is normally woven polypropylene, and the secondary backing is a latex or polyurethane coating. A herbicide has no way into any of that.

What nobody arguing about this has done, though, is read the label. A UK glyphosate label lists the situations the product is approved for, and that list is closed. Roundup ProActive names natural surfaces not intended to bear vegetation, permeable surfaces overlying soil, hard surfaces and amenity vegetation. Artificial grass is not on it, and it is not on any other label I have checked, in either direction. So nobody can show you a manufacturer approval, and nobody can show you a manufacturer prohibition either. The other honest unknown is the rest of the bottle, because the surfactants that make a spray cling to a leaf are the aggressive part of any formulation and nobody has published anything on how they behave on turf yarn. If you want certainty rather than reasoning, test your mix on an offcut from the installation or a hidden strip behind the shed, leave it a week and look at it.

The warranty is the part nobody selling you weedkiller mentions, and it is where the real risk sits. Artificial grass guarantees routinely exclude exactly this: the standard industry wording rules out damage from "use of cleaning chemicals, herbicides or pesticides", and UK suppliers use that clause word for word. One of them sells its own branded artificial grass weedkiller on the same website without disclosing what is in it. Another UK guarantee excludes weed growth itself, membrane or no membrane. Then again, one installer goes the other way entirely and its ten year warranty tells you that where airborne seed germinates on the surface, a weedkiller must be applied. The trade does not agree with itself, so the only warranty that counts is the one in your paperwork. Go and read it before you spray anything on a surface that was not cheap to lay.

The turf manufacturers are more use than the installers here, because a couple of them publish a real do-not-use list. One says never use bleach or sodium hypochlorite, because it damages the fibres, and never calcium chloride, ammonium nitrate, common salt or rock salt. Another warns that bleach, rust removers and concentrated chlorine cause discolouration and fibre breakdown, and that oils and petroleum products soak in and weaken the plastic structure over time. Hold that against the home remedy advice doing the rounds and the salt-and-vinegar recipe is ruled out by the people who made your lawn. Boiling water is the sly one, because it looks harmless. Polyethylene does not have to reach its melting point to be ruined. It softens and distorts below it, and a turf fibre is fine enough that softening alone mats it flat for good. The polyethylenes used in turf yarn are published as melting from around 105 degrees Celsius, and a kettle pours at 100, so you are working right up against it before you even count the softening that starts lower down. A flame weeder on a plastic lawn needs no further comment.

Residual "path and drive" weedkillers are the other thing to leave on the shelf, for two reasons. The Weedol Pathclear label restricts the product to natural surfaces not intended to bear vegetation and permeable surfaces overlying soil, and says do not use it on impermeable surfaces or surfaces underlaid with impermeable material, such as concrete, tarmac, decking and paved areas. An artificial lawn laid over a concrete slab or an old patio is exactly that, and the same label caps you at one treatment a year in any case. The second reason matters more: a residual works by leaving a barrier in the soil, and the weeds up here are not growing in soil.

That is the bit that usually gets left vague. Weeds in artificial grass, astroturf, fake lawn, whatever you call it, are hardly ever pushing up from the ground underneath. They root in the sand infill, in the fine dust and leaf litter that settles into the pile over a few years, and around the seams, the edges and the punched drainage holes in the backing. The root you need to kill is sitting a few millimetres above your weed membrane, not below it. That is why pulling by hand keeps failing, and why a soil-acting product is spending its money on nothing.

So what works is dull, and it works every time. Spot-spray a plain glyphosate concentrate, mixed to the rate on its own label, straight onto the leaf on a dry day, and keep it off the rest of the pile. Give it two to four weeks, because systemic means it has to travel, and anything that wilts within hours has burned the leaf and missed the root. Then brush the dead growth and the built-up debris out with a stiff brush, so the next seed that blows in has nothing to land in. The edges are a fitting problem rather than a spraying problem, so budget on doing them again each year. And if it is moss rather than weeds you are staring at, that is a different job and not one I cover here.