How to kill weeds – permanent solutions to banish these agricultural pests

Here's how to kill weeds so they don't grow back, whether they're growing through gravel, grass, or paving

killing weeds and stopping them from growing
(Image credit: Future PLC / Colin Poole)

Weeds are the plants that none of us asked for, the agricultural pests that we just can't seem to shake no matter how hard we try. If your garden is currently playing host to these unwanted interlopers, you're probably wondering how to kill weeds so that they don't come back again. 

Well, the good news is that you can clear weeds from your garden ideas and go back to admiring the plants that you actually chose to grow instead. Learning how to kill weeds is especially essential at this time of year, when we're about to start enjoying our gardens more and we want to fill it with colourful spring flowers.

'Weeds can be a nuisance for any garden and some can cause more problems than just being an eyesore,' says Sam Jenkinson, Garden Expert, Tiger. 'But luckily for gardeners, there are many methods we can use to get rid of them.'

The question is, how do we kill weeds, and fast? You may have weeds growing in between your paving stones or even on your gravel driveway, but wherever they are, you can learn how to kill weeds with the help of our essential guide.

How to kill weeds and stop them from growing

The methods in our guide will explain how to kill weeds so that they don't grow back, which is every gardener's dream. You may need to try multiple methods to find the one that gets rid of the weeds in your garden, but the experts have assured that you can learn how to kill weeds no matter what type you're dealing with.

1. Know what weeds you're dealing with

kill weeds and stop them from growing

(Image credit: Future PLC/Amateur Gardening)

Before removing any weeds, it is necessary to determine the species you are dealing with in order to ensure you choose the most effective method of removal.

Weeds are classified under two main categories in regards to their growing characteristics - annuals and perennials. Annuals are those that grow and sprout quickly and have an average lifespan of one year. Before they die they release hundreds of seeds which germinate and appear in the garden the following year. Common examples of annual weeds you might find in your garden are fat hen, chickweed, groundsel and hairy bittercress.

Perennial weeds on the other hand, return every year and typically develop extensive root systems, which make them extremely hard to eliminate. Examples of this type of weed are creeping thistle, brambles, bindweed and ground elder.

'To identify the type of weed you're dealing with, you can use an online weed identification tool or consult with a local gardening expert,' says Henry Bravo, Founder, SmartGardenHome. 'Remember that different weeds require different control methods.'

There are plenty of visual guides you can use to help you identify the weeds in your garden, such as the RHS guide to identifying common weeds.

2. Tackle annual and perennial weeds differently

'Annual weeds complete their lifecycle within a year and die off naturally, so removing them manually or with an herbicide should be sufficient,' explains Henry. 'Perennial weeds, on the other hand, have deep root systems and can regrow even after being removed. Dig out as much of the root system as possible for these weeds and use a herbicide specifically formulated for perennial weeds.'

Treating annual weeds before they set seed is essential to prevent them from spreading, so it's good to have a spot treatment on hand.

Try this: Roundup Fast Action ready-to-use weed killer 2.5ltrs, £3, B&Q

As explained by Henry, perennial weeds need to be tackled from the root. You could dig these weeds out by hand, but make sure you get the whole root. Leaving even the smallest piece can allow the weed to regrow. Use a knife to loosen the soil and lever up individual weeds that grow in beds and paved areas.

It's also a good idea to use a specialist weedkiller that targets the roots.

Buy now: Fiskars weed puller, £28, B&Q

3. How to stop weeds from growing between pavers

table and chairs with umbrella and growing weeds

(Image credit: Future Publishing Ltd / Colin Poole)

Weeds often leave patios and driveways looking unkempt by growing between the slabs. To prevent this, try using polymeric sand, available at Wickes. It has a naturally high pH that stops weed growth. All you have to do is pour it on the paving and sweep it into the joints (it works on gaps 1-5mm wide).

Already spotting dandelions and other weeds cropping up? Although it's a laborious and fiddly task, pulling them out by hand is a cheap and effective way to revive your patio ideas. The first step to take is to dampen the area between the pavers. This makes the weeds easier to remove.

Use gardening gloves, a weed knife with a hooked end, and a gardening kneeling pad, at Amazon and remove the weeds manually. Give the area a good sweep afterwards to remove any seeds that might have come loose in the process.

While you can use a pressure washer, we'd advise against doing so regularly, as it can cause damage to your paving over time. If that all sounds far too time-consuming, try pouring hot water on the gaps between paving slabs. You can also use baking soda to dry weeds out – pour it over your paved area and sweep into the cracks.

Another cupboard staple that's often recommended is white vinegar. Spray it on the affected area to help kill off unwanted growth. Cass Heaphy Digital Director at Paving Direct warns not to use salt to kill weeds as it can damage paving, and recommends using an organic herbicide if weeds are persistent.

4. How to stop weeds from growing through gravel

brick wall with trees and armchair

(Image credit: Future Publishing Ltd / Jonathan Jones)

Weeds will find a way of growing anywhere, including your gravelled driveways and outdoor living spaces. Knowing how to kill weeds growing in gravel can be done swiftly, and there are a few solutions you can try. 

'One method is to use boiling water and vinegar to kill the weeds down to the root'm says gardening expert Henry. 'You can pour the mixture directly onto the weeds, being careful not to splash it on surrounding plants. Another option is to use a pre-emergent herbicide, which will prevent weed seeds from germinating in the first place.'

If this doesn't work, William Mitchell, Gardening Expert at Sutton Manor Nursery, recommends digging the area affected by the weeds to get rid of both the roots and the seeds. This will kill the weed and hopefully prevent it from returning.

‘All gravelled areas should lay on top of a landscape fabric membrane,' William explains. 'This acts as a layer between the soil underneath and the gravel on top. It makes it extremely difficult for weeds to pop through and into the gravel.’

5. How to kill weeds on a lawn

garden area with trees and lawn

(Image credit: Future PLC/Brent Darby)

Any patch of grass will act as a magnet for unwanted plants, making it virtually impossible to stop seeds from infiltrating and germinating amongst the blades of grass. Good lawn care can help though. Remove space for weeds to flourish by mowing regularly and over-sewing bare patches with grass seed.

Hand weeding can be a faff, but it's a good – and natural – way to stop a small group of weeds to spread. You might want to invest in a daisy grubber – the classic two-pronged tool with a lever-action for pulling daisies and other weeds out of a lawn without spoiling the grass.

For larger infestations, you'll need to use a selective weedkiller that won't kill the grass. Granular selective weedkiller is often combined with a lawn feed and conditioner and is supplied in 'easy-flow' pans. These kill weeds and moss and feed the grass, too. They're easy to apply and work well.

Alternatively, water-on selective weedkillers contain a range of chemicals to target specific weeds. They are relatively cheap and are easy to use.

Buy now: Evergreen complete 4 in 1 lawn care tub, £10, Wickes

6. How to kill weeds with weedkiller

killing weeds and stopping them from growing

(Image credit: Roundup)

Weedkillers, such as Roundup and Resolva, kill weeds from the inside out. When sprayed onto the leaves of the weed, they are absorbed and transported to the growing points of the plant – including the roots.

'But it's important to note that weeds will only take up the weedkiller when they are actively growing,' says Janne Hasen, Controls Category Manager for Roundup. 'Which is why treatment during the warmer months is recommended. Also, spot weedkillers are not selective and will kill any plant they touch, so be careful when applying them,

Penetration through the leaves takes some time and effectiveness can be reduced if it rains within six hours of application. Weedkiller should therefore be applied on a dry calm day in order to achieve the best results.

How often should you weed, and when?

The best approach to wage war on weeds is to make time for a weekly weed workout. Hoe the soil when the surface is dry, and on a hot sunny day, or when there's a good breeze.

'If you’re pulling the weeds by hand, it’s best to do this either early in the morning or late in the evening, because this is when it's more humid,' says John Dempsey, Gardening Expert, 'This means the soil will be looser, making it much easier for you to pull the weeds out right down to the root.'

But are there certain times of the year when weeding is more important? According to John, yes. 'Weeding is most important between the months of March and June. This is when you should actively try to weed once a week. After that, you’ll likely find that you won’t need to weed as much.'

What is the quickest way to kill weeds?

If you want to learn how to kill weeds quickly, one of the best things you can do is boil the kettle and pour the hot water on the weeds.

'Boiling water can be used to eradicate weeds within a couple of days,' says Sam Jenkinson from Tiger. 'Pour this on the base of the plant to instantly shock the weed and any seeds that are covered. Be very careful where this is poured, only use small amounts and make sure it doesn’t splash onto plants and flowers that you want to live.'

You can also use a herbicide or specialist weed killer to do the job quickly. 'In terms of the quickest way to get rid of weeds, using a herbicide will typically provide faster results than manual removal,' says Henry, SmartGardenHome. 'However, it's important to remember that herbicides can harm other plants and the environment if not used correctly. Always follow instructions carefully and consider using organic, non-toxic options if possible.'

What kills weeds permanently?

For learning how to kill weeds permanently, it's important to tackle them at the root, especially perennial weeds. 

'One of the main ways to get rid of weeds permanently is to dig them up and remove all of the roots to stop any further growth,' says Henry. 'This can be done with a trowel, but be sure to be gentle so that no bits break off as this may cause more weeds. No matter how weeds are removed it is essential to discard them properly, ensure no remnants are left and don’t add to any compost piles.'

Another way to kill weeds for good is to use a strong acid to burn them away. Experts recommend either vinegar or lemon juice for this. 'Cut a lemon in half and then squeeze the juice over the weed,' says gardening expert John. 'The citric acid in the lemon should kill the weed within a few days. This method is especially effective when there is strong sun shining on the weeds. The lemon juice can be used as it is, there is no need to dilute it.'

Does vinegar kill weeds permanently?

You probably already know that cleaning with vinegar is one of the fail-safe ways to kill unwanted bacteria, but can this household staple get rid of weeds for good?

'The acetic acid inside vinegar is effective on smaller weeds and will get rid of any that are visible,' says Sam Jenkinson. 'It is better to use vinegar on gravel and paving rather than grass as it can alter the soil and prevent anything from growing in the future.'

The only risk with using vinegar for killing weeds is that the acid may kill the leaves before reaching the root system, which will result in them growing back. But if the vinegar can penetrate the roots, it will get rid of the weeds for good. 

Pour a high quantity of vinegar onto the roots for a more permanent solution. You can mix this with other actives, like salt and washing-up liquid, which will combine together to make a powerful weed killer.

'Using a vinegar and dish soap mixture did the trick and killed the weeds in my own garden down to the root,' says Henry Bravo. 'It was a small victory, but it felt like a major accomplishment in my ongoing battle against weeds.'

Amy Cutmore

Amy Cutmore is an experienced interiors editor and writer, who has worked on titles including Ideal Home, Homes & Gardens, LivingEtc, Real Homes, GardeningEtc, Top Ten Reviews and Country Life. And she's a winner of the PPA's Digital Content Leader of the Year. A homes journalist for two decades, she has a strong background in technology and appliances, and has a small portfolio of rental properties, so can offer advice to renters and rentees, alike. 

With contributions from