Can bio-washing powder kill weeds? Yes, but it comes with a warning from experts

The secret to a weed-free patio is already under your sink

Garden shed with lawn surrounding, trees, plants in planters
(Image credit: Future / Heather Young)

If your patio is sporting unwanted greenery or your flowers are being ravaged by weeds, you’ll know just how quickly these undesirable plants can spread. While the key is to get rid of them as soon as you can, the question on everyone’s lips is: Can bio washing powder kill weeds?

Of course, there are countless chemicals and methods for how to kill weeds. But if you’re on a budget or looking to steer clear of harsh chemicals that could harm your patio ideas, opting for affordable and accessible alternatives might be higher up on your priority list. 

So, what can you use? The word on the street is that washing powder is the key to banishing weeds from your garden once and for all. But as we’re bombarded with so-called “hacks” all the time, we’re used to certain products falling short of their hype. That’s why we’ve decided to ask the experts whether bio-washing powder really can kill weeds. 

Can bio washing powder kill weeds? 

Whether you want to remove weeds from a patio or get rid of weeds in gravel, you’ll be happy to know that biological washing powder can indeed kill weeds. 

Front garden with blue door

(Image credit: Future PLC)

Tom Clifford, garden landscaping expert at Gardenstone explains, ‘Strong chemical weed killers, although effective, can often be harmful to your patio surface, especially if it's made from delicate stone.’

‘Washing powder offers a gentler option that shouldn't harm your patio surface but will effectively kill weeds. In addition, washing powder is a regular household object, making it much more accessible and affordable than chemical weed killers.’

So, how does it work? Well, a major ingredient in bio-washing powder is boron, and boron is incredibly toxic to plant life. When exposed to boron, plants will start to wither and die. But bio-washing powder doesn’t stop there. 

table and chairs with umbrella and growing weeds

(Image credit: Future Publishing Ltd / Colin Poole)

Anyone who has ever used biological washing powder before will know that it’s great for cleaning dirty clothes and removing stains, and it essentially does the same thing with weeds. In fact, the soaps and detergents in the bio-washing powder strip the weeds of their natural oils that protect the leaves. When this natural coating is broken down, it leaves the weeds incredibly vulnerable to boron and other pathogens. 

Before too long, they’re infecting the weeds and killing them from the roots up. This will see them shrivel and dry up, allowing you to simply pull them up or even brush them away. It’s incredibly easy to get rid of weeds in your garden this way, too.

Craig Morley, a gardening expert from Budget Seeds, says, ‘To use washing powder to kill weeds, sprinkle the powder into gaps in the paving or onto affected areas, and then pour boiling water over it. Once the leaves have turned brown and the weeds begin to wilt, you can sweep them away easily. It can also be used to remove moss from in between paving effectively.’

The exterior of a modernised and extended 14th century farmhouse.

(Image credit: Future PLC/Polly Eltes Photography)

If you’re looking for a more targeted approach, Tom has suggested another option. ‘Alternatively, you can create a mixture of washing powder and warm water in a spray bottle and generously soak each of the weeds. This may help with targeting the weeds more directly and avoid getting any of the mixture on the patio surface.’

However, you need to be careful when using this method. As boron is toxic to plant life, you should avoid using it anywhere near plants that you want to keep alive - like those in your garden borders, and especially if you want to get rid of weeds in your lawn. 

In fact, experts advise against using this concoction anywhere near your grass, as you run the risk of killing it in the process. 

John Marshall, Landscaping Expert at Wenningdale Escapes, explains, ‘Washing detergents including boron will help kill weeds. However, they will also do the same to your grass - which no one wants! So we recommend avoiding putting it near your grass and flowers and if you are using it on paving or pathways, make sure you sweep up any additional residue to avoid it blowing into the grass or other green parts of the garden.’

With this in mind, you should also keep your children and pets away from the area if you choose to use this method. But if it’s used correctly, you can kill weeds and clean your patio at the same time. And that’s a win-win in our books. 


How long does it take for washing powder to kill weeds?

It can take anywhere from a few days to a few weeks for washing powder to kill weeds, as this all depends on the severity of the issue. If they are relatively young and new weeds, they could only take a few days to turn brown.

However, if your patio is covered in weeds and you want to ensure they’re all dead, it’s best to give them as much time as possible. When they’re brown, dry, and crusty, you should be able to pull them up or sweep them away. In some cases, they may even turn to dust. 

If it rains a lot during this waiting game, you may need to reapply the water and washing powder concoction.

Does washing powder kill weeds on a patio?

Yes! Washing powder is extremely effective at killing weeds on a patio, but you need to be careful when choosing this method. 

To kill weeds on a patio, simply sprinkle the weeds with washing powder, pour boiling water over the top, and let it work its magic for a week or so. Just make sure that you don’t cover anything that you want to keep alive, as the boron inside of this washing powder will kill any plant life it touches.

For this reason, you should also keep it away from your lawn. 

Does Aldi washing powder kill weeds?

Yes, any washing powder that contains boron should kill weeds in your garden. If you’re not sure if Aldi washing powder will kill weeds, it’s a good idea to check the ingredients list. If it doesn’t have boron in it, it’s unlikely to be as effective. 

Who knew washing powder had so many handy uses? 

Lauren Bradbury

Lauren Bradbury is a freelance writer and major homes enthusiast. She graduated with a Bachelor’s degree in English and Creative Writing from the University of Chichester in 2016, before dipping her toe into the world of content writing. After years of agency work, writing everything from real-life stories to holiday round-ups, she decided to take the plunge and become a full-time freelancer in the online magazine world. Since then, she has become a regular contributor for Real Homes and Ideal Home, and become even more obsessed with everything interior and garden related. As a result, she’s in the process of transforming her old Victorian terraced house into an eclectic and modern home that hits visitors with personality as soon as they walk through the door.