How to Get Rid of Weeds Between Patio Slabs

There’s nothing that undoes a tidy patio faster than a row of weeds sprouting through the joints. You pull them out, and a fortnight later they’re back, usually thicker than before. That’s because most of the quick fixes people reach for, a kettle of boiling water, a squirt of vinegar, only deal with the weed you can see, not the gap that let it grow in the first place.

The good news is that clearing existing weeds is straightforward, and stopping them coming back is even more straightforward once you understand why they’re there. This guide is written for UK homeowners, and covers the fastest ways to get rid of weeds between patio slabs, how to use weedkiller properly if you need it, and, most importantly, the long-term fix that means you stop doing this job every summer.

Why weeds keep growing between your patio slabs

Weeds don’t grow through solid stone. They grow in the gaps: the joints between your slabs. If those joints were originally filled with sand, or with a jointing compound that’s worn thin over the years, you’ve effectively got a strip of loose growing medium running across your whole patio. Add a bit of blown-in soil, some airborne seeds, and a bit of rain, and it’s as good a spot for a weed to germinate as your flower beds.

Poor drainage makes it worse, since damp joints stay hospitable to seeds for longer, and joints on the sunnier side of a patio tend to be the first to sprout. The pattern is nearly always the same: wherever the jointing has failed, was never done properly, or is just loose sand, that’s where the weeds show up.

Quick ways to remove weeds you already have

If you need your patio looking respectable this weekend, here are the fastest non-chemical methods, roughly in order of effort.

Manual removal. A patio weeding knife, an old kitchen knife, or a wire brush run along the joint line will pull weeds out roots and all. It’s the most reliable “kills it properly” option for small numbers of weeds, if a bit slow across a whole patio, and it needs repeating regularly since it doesn’t stop new seeds settling into the same gap.

Boiling water. Pour it directly onto the weed and the surrounding joint. It scalds the leaves and roots on contact, is completely non-toxic, and costs nothing, though it tends to kill only what it touches, so it’s best used on small, young weeds rather than established, deep-rooted ones.

Vinegar. Household white vinegar works by dehydrating the leaf and stem, and is most effective on small, young weeds rather than mature growth. A stronger vinegar and salt mix will scorch tougher weeds too, but salt can affect the soil for a while afterwards and isn’t kind to nearby plants or borders, so use it with a bit of care if your patio backs onto planting.

Baking soda. Sprinkle it directly onto damp weeds and joints. The high sodium content dehydrates the plant in a similar way to salt. It’s cheap and simple for the odd stray weed, but like salt-based treatments it can harm nearby plants and grass if it washes into borders, so keep it away from anything you want to keep growing.

How to stop weeds growing between paving slabs with weedkiller

For a heavily overgrown patio, or joints that keep sprouting no matter what you try, a dedicated weedkiller is usually the quickest way to get on top of it in one go. UK homeowners have plenty of path and patio weedkillers to choose from in garden centres and DIY stores, so it’s worth knowing what you’re actually buying.

Most path and patio weedkillers fall into two types. Contact weedkillers kill off the visible leaf and stem quickly but rarely touch the root, so regrowth from perennial weeds is common. Systemic weedkillers, typically glyphosate-based, are absorbed through the leaves and carried down into the root system, killing the whole plant rather than just what’s above the joint. This is generally the more effective option for anything established or recurring. Some path weedkillers also contain a residual ingredient that stays active in the joint for several months, stopping new seeds from germinating there at all.

A few tips for getting the best from it:

1. Apply on a still, dry day. Rain within a few hours will wash the product off before it’s absorbed, and wind can carry spray onto nearby plants or lawn.
2. Treat weeds while they’re actively growing. Spring and early summer, when growth is strongest, is when systemic weedkillers are absorbed most effectively.
3. Follow the dilution and reapplication instructions on the label. Stronger isn’t always better. Overdosing doesn’t kill weeds faster and can damage the surrounding stone.
4. Keep pets and children off the treated area until it’s dried, and be cautious using any weedkiller near ponds, vegetable patches, or borders you want to protect.

Is it better to pull or spray weeds?

It depends on what you’re dealing with. Pulling is instant, free, and fine for the odd weed here and there, but if you’re not getting the full root out, which is easy to miss in a tight paving joint, it’ll usually grow back within a few weeks. Spraying with a systemic weedkiller takes longer to show results, often one to two weeks, but kills the root as well as the leaf, so it deals with the problem more completely. For a patio with just a handful of weeds, pulling is usually enough. For widespread or recurring growth, spraying first and then repointing the joints (see below) is the more lasting combination.

Pressure washing and flame weeding

A jet wash will blast weeds and moss off in minutes and leave your slabs looking brand new. It’s also a good way to clean out old, crumbling joints before repointing. The catch: if your joints are filled with loose sand, pressure washing often washes the sand straight out along with the weeds, leaving the joint emptier than before, which means it grows back faster next time.

A patio weed burner or blowtorch attachment wilts weeds almost instantly with heat rather than chemicals. It’s satisfying to use and chemical-free, but like boiling water it only kills the visible growth, so deep-rooted weeds tend to resprout.

The real fix: repointing with a proper jointing compound

Every method above deals with the weed. None of them deal with the joint. If your patio has sand-filled joints, or joints that have eroded, cracked, or gone mossy over the years, you’re going to be back out here with the kettle or the spray gun every few months, because the growing medium is still sitting there waiting for the next seed.

The fix that actually lasts is repointing the joints with a proper brush-in jointing compound rather than loose sand. You may also see this approach called polymeric sand: a sand-based jointing product with a binding agent that hardens once watered in, rather than ordinary kiln-dried sand, which stays loose forever. A compound like Tile Mountain’s MapePave Brush In Grout works on the same principle. It sets hard once it’s watered in, sealing the joint so there’s no loose material left for weeds to root into and no gap for seeds to settle in. It’s the same idea as grouting a tiled floor: once the joint is solid, weeds simply have nothing to grow in.

Here’s the process in outline:

1. Clear out the old joints. Use a plugging chisel, a joint raker, or a pressure washer on a low setting to remove old sand, moss, and any remaining weeds down to a firm base, going roughly two-thirds of the way down the joint depth. A stiff brush or a wet-and-dry vacuum works well for lifting out the loosened debris afterwards.
2. Let the patio dry. Most jointing compounds need a dry surface to bond properly, so pick a dry day and give the slabs time to dry out fully.
3. Brush the compound in. Pour the jointing compound over the slabs and use a stiff broom to work it into the joints, packing them fully and brushing off any excess from the surface of the slabs before it cures.
4. Compact and cure. Follow the product instructions for watering in or curing time. Once set, the joint is solid, weatherproof, and far too dense for a weed to push through.

It’s a weekend job for an average-sized patio, but it’s the difference between fighting the same weeds every year and not thinking about it again for a long time.

How to stop patio weeds from coming back again

Once your joints are properly filled, a few habits will keep your patio looking sharp with very little ongoing effort.

Give it a sweep every few weeks to clear out windblown soil, seeds, and organic debris before they get a chance to settle into the joints. Deal with moss early, since it holds moisture and creates a foothold for weed seeds to germinate on top of it, and moss is a particularly common problem on UK patios given how much rain and shade most gardens get through the year. Seal the surface: a sealing treatment locks the joints and slabs against water and staining as well as weed growth, so for porcelain or natural stone paving, a pre-grout or sealing product such as LTP Porcelain Tile Protector is worth applying alongside a fresh repoint. And keep an eye on the edges and borders where your patio meets a lawn or flower bed, since that’s the most common route for weeds and grass to creep back in from the side, not just up through the joints themselves.

Combining approaches works best: repointing to remove the growing medium, sealing to protect the new joints, and a quick sweep or spot-treatment now and then for anything that does blow in.

FAQs

What kills weeds between patio pavers?

Anything that reaches the root will kill a weed properly: hand-pulling the full root, a systemic (glyphosate-based) weedkiller, or repeated boiling water and vinegar treatments on younger growth. For a lasting result, killing the weed and then filling the joint with a proper jointing compound stops new ones taking root in the same spot.

Does putting sand between slabs stop weeds?

Not on its own. Ordinary kiln-dried sand fills the gap but stays loose, so it’s still an easy spot for seeds to settle and germinate. A binding jointing compound, sometimes sold as polymeric sand, hardens in place and is far more effective at keeping weeds out than loose sand.

What do I use to fill the gaps between paving slabs?

For a genuinely weed-resistant finish, use a brush-in jointing compound rather than loose building sand. A product like MapePave Brush In Grout sets solid once watered in. Loose sand is cheaper and easier to apply but will need topping up regularly and won’t stop weeds long-term.

Is it better to pull or spray weeds?

Pulling is quick and works fine for the odd isolated weed, provided you get the whole root out. Spraying with a systemic weedkiller takes a week or two to show results but kills the root system too, making it the more reliable choice for widespread or recurring weeds. Many UK homeowners use both: spray first, then pull out the dead growth once it’s died back.

Does vinegar kill weeds permanently?

Not usually. It scorches the leaves effectively but rarely kills the root system of established perennial weeds, so regrowth after a few weeks is common. It works best as a quick knockdown on small, young weeds between more permanent fixes.

Is bleach safe to use on patios?

It’s best avoided. Bleach can discolour natural stone and some porcelain finishes, and it’s harmful to nearby plants, pets, and soil life. A dedicated patio weedkiller or the vinegar and boiling water methods above are safer choices.

How often should I re-grout my patio?

A properly installed jointing compound can last many years, but sand-filled joints may need topping up annually. If you’re noticing weeds in the same spots every year, that’s usually the sign it’s time to repoint rather than just re-weed.

Will pressure washing get rid of weeds for good?

It clears them visibly, but if your joints are sand-filled, pressure washing often washes out the sand too, leaving the joint more exposed and quicker to weed up again. It’s best used as a clean-up step before repointing, not as a standalone weed treatment.

In summary

Pulling weeds from between your patio slabs is a five-minute job, but it’s one you’ll be doing on repeat unless you deal with the joint underneath, not just the weed on top. Boiling water, vinegar, baking soda, and weedkiller will all clear what’s growing today, but a patio with solid, properly filled joints is one that simply doesn’t grow weeds in the first place.

If your joints are sand-filled, worn, or you’re pulling the same weeds year after year, repointing with a jointing compound such as MapePave Brush In Grout, and sealing with something like LTP Porcelain Tile Protector, is the combination that actually solves the problem for good. Browse Tile Mountain’s jointing compound and paving care range to get started.