You get weeds out of your paving best without chemicals by combining hand weeding (a paving knife) for the root with hot water or a weed burner for the quick work. Spraying Roundup isn’t the answer for most gardeners anymore: glyphosate is heavily restricted, banned on paved surfaces in many places, and controversial for good reason. And watch out: those “natural” tips with vinegar and salt are not a good idea. They’re not even permitted and they wreck your soil. In this article I line up the 7 methods that do work, with cost, time and how often you need to repeat, plus how to stop the weeds coming back.
First: why skip the chemicals
Quick lay of the land, because this is exactly why you’re here.
Chemical weedkillers are on the way out for the home garden, and even where they’re still on the shelf, plenty of gardeners no longer want them near the patio. Glyphosate, the active ingredient in Roundup, is restricted or banned on paved surfaces in a lot of places and remains controversial. On paving there’s another catch: the stuff washes straight off hard surfaces into drains and groundwater, unfiltered.
So whether you like it or not, it’s going to be chemical-free. The good news is that the alternatives work perfectly well, as long as you know what you’re doing. And that “what you’re doing” is exactly where most people go wrong.
The big mistake: vinegar and salt
You’ll find the advice everywhere online: tackle weeds with household vinegar or a handful of salt. Sounds nice and natural, right? Well. Don’t.
Why not salt: salt stays in the ground for years. Your soil turns barren from it, including for the plants you do want. It leaches into the groundwater, attacks concrete, and garden birds that drink from a salty puddle get sick. You solve a small niggle and create a big problem.
Why not vinegar: vinegar only scorches the leaf. The root survives, so the weed is simply back a week later. And the environmental damage is serious. Research shows there’s already a risk to neighbouring plants from 6.6% acetic acid, to aquatic life from 36%, and to soil life from 54%. That soil life is your wild bees and digger wasps. You don’t want to get rid of them.
And then the legal bit, which almost nobody mentions. You may only use products that are approved for use as a weedkiller. Household vinegar and table salt aren’t on that list. Using them to kill weeds is therefore simply not permitted, and gardening bodies like the RHS advise against both.
In short: vinegar and salt aren’t an eco-friendly trick, they’re a fake fix that turns your soil, your wildlife and the rules against you. Below are the methods that actually hold up.
The 7 chemical-free methods at a glance
Every method has its place. One is fast, another gets the root, a third is free. Here’s the overview first, then I’ll walk you through them one by one.
| Method | Gets the root? | Speed | Cost | Repeat |
|---|---|---|---|---|
| Hand weeding / paving knife | Yes (taproot: mostly) | Slow, physical work | One-off ~£10–20 | Rarely, if the root comes up |
| Weeding brush (steel) | No, surface only | Fairly fast | £15–150 (hand/cordless) | Every few weeks |
| Boiling/hot water | Partly | Fast | Free (leftover water) | 3–4x per season |
| Weed burner (gas) | No, top growth only | Very fast | From ~£45 | 3–4 rounds, 2 wks apart |
| Hot-air weeder (electric) | No, top growth only | Fast | £40–120 | 3–4 rounds |
| Pressure washer | No | Fast | £80–300 | Often (speeds up regrowth) |
| Soap spray (phosphate-free) | No | Reasonable | A few pounds | Repeat |
1. Hand weeding with a paving knife
The classic, and for good reason the most sustainable. A paving knife with a hooked end catches the plant, root and all, out of the joint. If the taproot comes with it, that plant is genuinely gone, no regrowth.
No knife in the house? A stick with a stout nail through the end does the same thing. Fred budget.
Downside: it’s on-your-knees work and it takes time. But in the long run it’s the cheapest and most effective way, especially if you do it regularly and the weeds are still young.
2. The weeding brush
A sturdy steel joint brush on a handle, or an electric or cordless version. You work standing up and scrub the weeds out of the joint. Kind on your back and fast across a big patio.
Watch one thing: don’t brush like a maniac. Go too hard and you open up the joints and make the paving surface porous. And it’s precisely in open, porous joints that green film and fresh weeds take hold faster. You’d be sawing off the branch you’re sitting on.
The brush also doesn’t get the root, so count on repeating every few weeks.
3. Boiling and hot water
Simple, free and surprisingly effective. Boiling water damages the plant cells straight away and, unlike chemicals, leaves no harmful residue behind in the ground.
The smartest version: don’t boil fresh water to pour over your weeds, use the leftover water from your pasta, potatoes or veg. You’ve already heated that water, so it costs you nothing extra and not a puff of gas more. Pour it precisely, only onto the weeds, not over your borders.
With this home method you mainly hit the top growth, so repeat a few times per season. Professional hot-water kit goes deeper and reaches the fine roots too, but you don’t need that equipment at home.
4 and 5. The weed burner (gas or electric)
A burner heats the plant so briefly that the cells burst. You don’t actually have to burn the weed or char it black: a few seconds of heat is enough, after which the plant dries out on its own within a few hours. So sweep gently over it, don’t hold still.
There are two flavours. The gas burner (with a cartridge or bottle) is the familiar one. The electric hot-air weeder does the same with hot air instead of a flame, is a touch greener and just as effective. No open flame, so a bit safer in dry spells.
Important to know: a burner only kills what you can see, not the root. The first little plants are back after about two weeks. If you want to truly exhaust the root, you need 3 or 4 rounds with roughly two weeks between each. Every time the plant has fewer reserves, until it gives up.
6. Pressure washer
Fast, and it cleans the film off your slabs at the same time. But there’s a snake in the grass: the hard jet blasts your joints open and makes the paving surface porous. The result is that green film and weeds actually come back faster afterwards. So use it sparingly and top your joints back up afterwards (see prevention below).
7. Homemade soap spray
For the enthusiast: 10 grams of biodegradable, phosphate-free soap dissolved in 2.5 litres of water, in a plant sprayer. This works on the leaf, not the root, so again the rule is: repeat. A fine extra, not a miracle cure.
Safety with the weed burner: the checklist
A burner is fire (or glowing hot air) on your patio. Take it seriously, because a small patio fire jumps to a dry hedge or wooden fence in no time. Run through this before you start:
- Only on a dry, still day. Wind blows the heat to places you don’t want it.
- Never during drought or a fire ban. Check that quickly if it hasn’t rained for a while.
- Keep water or a fire blanket to hand. Always. Costs nothing, saves panic.
- Stay clear of anything flammable. Wooden fence, dry hedge, wall planting, garden furniture: keep your distance.
- Sweep, don’t stand still. A few seconds per plant is enough. Longer is a waste of gas and a fire risk.
- Keep children and pets inside. A burner, and the slabs after it, stay hot for a while.
Clever: which approach for which weed?
Not every weed asks for the same thing. A detail almost nobody mentions, but one that saves you a lot of repeat work.
Deep taprooters (dandelion, thistle) have one long root that runs deep into the joint. Burning or hot water does little here, because the root simply resprouts. Weed or lever these out with the knife, ideally after a shower of rain when the ground is soft, so the whole root comes with it.
Shallow shoots, moss and seedlings sit loosely in the joint. Those you handle nicely with the burner, hot water or the brush. Quick work.
Best moment: weed after a good shower of rain, when the roots slide out of the damp joint most easily. And start early in the season, while the weeds are still young and shallow-rooted. The earlier, the less work.
Prevention is better: stopping weeds coming back
All that clearing is bailing out a boat with the plug still open if you leave the joints bare. With a bit of prevention you keep the weeds down for good.
- Fill your joints with weed-suppressing jointing sand. This polymeric sand sets slightly, holds back germinating weeds and still lets water through. The best weapon you’ve got.
- Lay landscape fabric under new paving. If you’re redoing a patio anyway, put (biodegradable) landscape fabric under the sand layer.
- Sweep regularly. Seed that can’t settle never becomes a weed. A broom is your cheapest maintenance tool.
- Sort out good drainage. Puddles and damp in the joints are an invitation to moss and weeds.
- Consider fewer slabs, more green. The advice is to keep paved area limited. A border or ground cover where a few slabs were gives you less weeding, and helps against flooding and summer heat. Two birds with one stone.
Common mistakes
- Using vinegar or salt. Doesn’t touch the root, damages your soil and isn’t permitted. Just don’t.
- Burning once and thinking you’re done. Without repeating, the root resprouts within two weeks.
- Brushing or pressure-washing too hard. You open the joints and actually speed up regrowth.
- Weeding rock-hard, dry ground. The root snaps and stays put. Wait for a shower of rain.
- Using the burner in drought or wind. Fire risk. Pick a still day after rain.
- Only fighting, never preventing. Without weed-suppressing jointing sand you’ll be at it forever.
Frequently asked questions
Does vinegar really work on weeds between paving?
Short answer: no, not really. Vinegar only scorches the leaf, the root survives and the weed is back within a week. On top of that, vinegar is harmful to soil life and aquatic organisms and isn’t permitted as a weedkiller. Go for hand weeding or hot water instead.
Is salt a good alternative to chemicals?
No. Salt stays in the ground for years, makes your soil barren, leaches into the groundwater and harms garden birds. Like vinegar, it isn’t approved as a weedkiller either. The damage is greater than the problem you’re solving.
Can I still use Roundup or glyphosate at home?
Glyphosate is restricted or banned on paved surfaces (patio, drive, paving paths) in many places and remains heavily controversial. Either way you’re better off with the chemical-free methods in this article, which are kinder to your soil, your pets and pollinators.
What’s the fastest way to clear weeds between paving?
A weed burner or hot-air weeder gives the fastest visible result: a few seconds of heat and the plant dries out within hours. If you want it to genuinely stay gone, hand weeding with a paving knife (root and all) is more effective in the long run. The best approach combines both.
Do weeds come back after burning or boiling water?
Yes, after one treatment they do. Burning and hot water kill the top growth, but not the root. That resprouts after about two weeks. Count on 3 or 4 rounds, two weeks apart, to exhaust the root. With hand weeding that lifts the root, repeating usually isn’t needed.
Weed burner or hot water: which is better?
The burner is faster and covers a big area. Hot water (especially the free leftover water from your pasta or veg) is cheaper, energy-neutral and safer, because there’s no flame. For most gardens hot water is the sensible choice; if you’ve got a lot of paving, a burner is handier. Both need repeating.
How do I stop weeds coming back between my slabs?
Fill the joints with weed-suppressing jointing sand, sweep regularly so seed can’t settle, and sort out good drainage. If you’re laying new paving, use landscape fabric underneath. And consider swapping a few slabs for greenery: less paving means fewer weeds and better protection against flooding and heat.
Get stuck in in the garden
Keeping weeds between your paving under control doesn’t need chemicals and doesn’t need any fuss. A paving knife, some leftover water from the kitchen and the right joint filling get you a long way. And the best part: your soil, your bees and your neighbourhood birds stay healthy.
Want more garden projects with a clear step-by-step approach and precise measurements? At Fred’s DIY Plans you’ll find worked-out build plans for your garden and patio, so you can get going without guesswork.
Happy building.
Fred