How to kill weeds but not grass – 6 expert methods for a greener, healthier lawn (2024)

When weeds pop up in your otherwise spotless lawn there can be a brief moment of despair. Most products or DIY home hacks targeted towards getting rid of weeds can also damage grass too, so we gardeners are often left with the question of how to kill weeds but not grass?

Even if your lawn has become riddled with pernicious plants, there is no reason to give up on achieving a perfect patch of grass this summer. Simply by adapting how you get rid of weeds will help you towards a lush lawn in no time, experts say.

We have spoken to gardening professions, who explain six simple ways you can relieve your lawn of weeds without killing off any precious grass.

How to kill weeds but not grass

‘Before you can effectively remove weeds from your lawn, you need to know what types of weeds exist in your garden,’ begins David Angelov, master gardener at Plant Parenthood. ‘There are two main types of weeds: annual and perennial. Annual weeds grow and die within a single growing season, while perennial weeds come back year after year.’

Using salt to kill weeds is too harsh for your grass, while using cardboard for weed control leaves unsightly brown patches. Here are some alternative suggestions.

David Angelov

David is an active gardener growing his appreciation for plants every day. He specializes in formal and informal gardens maximizing clients' connection to nature.

1. Dig weeds up by hand

If you take pride in your lawn, then you will likely be used to tasks such as aerating a lawn and scarifying a lawn. You may, then, be unsurprised to hear that one of the best ways of removing weeds from grass without damaging it is to do it manually.

'To get weeds out of grass without damaging the turf, one of the simplest and most effective options is to remove them by hand,' says Drew Swainston, a former professional gardener and Content Editor for Homes & Gardens. 'This allows you to focus on each weed one by one and make sure you remove the full weed and its root to prevent it from coming back.

‘When you are dealing with perennial weeds, such as dandelions and plantain, both common lawn weeds, failure to remove the roots will result in it growing back again quickly,' says Drew. 'Scour the lawn for weeds, take hold of each one firmly, and pull the whole plant out. If needed, use a garden fork or garden weeder, available at Amazon to get underneath the weed and lever it out of the lawn. The grass will quickly grow to fill any space left by the weed.’

Drew Swainston

Gardening piqued Drew's interest and he studied for a Level 3 Horticulture qualification. This opened up the chance to work as a professional gardener for several years. His journey saw him have the fantastic opportunity to work at the world famous arts and crafts garden Hidcote Manor Garden in the UK, and he also spent several years at Hanbury Hall gardens in the West Midlands, UK. During his gardening career he also specialized as a kitchen gardener.

2. Improve the health of your lawn

There is more to a good, healthy lawn than simply planting grass seed; getting your lawn care regime right can help your grass fend off unwanted weed growth. ‘A healthy lawn is less likely to have weed problems,’ explains David Angelov of Plant Parenthood.

'You may also want to consider fertilizing your lawn and overseeding bare areas to help promote healthy grass growth (reducing weed growth), he adds.’

The main offenders on lawns are daisies, buttercups, clover, and moss. The best way to deal with them organically is to improve the health of your lawn and encourage vigorous grass growth – try feeding, aerating with a garden fork, such as this model from Amazon, and scarifying with a rake - this model from Amazon is top rated.

Lawn weed killers are often combined with feed and can be sprinkled or sprayed over your lawn. Apply to lawns any time between April and September when weeds are actively growing – don't apply more than twice in a year and leave a three-month interval in between.

3. Keep on top of mowing

If your grass is being taken over by common lawn weeds such as dandelions, one of the easiest ways to prevent them growing and spreading is to let your lawn mower do the hard work for you.

‘Make sure to mow your lawn regularly and not cut it too short, as well as watering it deeply, but infrequently,' explains David Angelov of Plant Parenthood.

If your lawn mower has a mulching option where it spreads the grass clippings straight back onto the lawn to feed the grass, it's important not to use this option when weeds such as dandelions are setting seed in mid to late spring. All you'll succeed in doing is spreading the seeds back into your grass.

A better option would be to keep the bagging attachment on your mower and get rid of the grass clippings that contain the seedheads instead.

4. Sprinkle on corn gluten meal

Sprinkling a layer of corn gluten meal over your lawn will benefit the lawn itself (a by-product of corn starch and corn syrup production, it contains protein and nitrogen), and is said to suppress weed germination.

Corn gluten meal is non-toxic to humans and animals, and is most effective if applied in late March to mid-April, a month or so before crabgrass starts to germinate. Sprinkle liberally, water, then let the soil dry out. You can buy Johnathan Green corn gluten meal lawncare products from Walmart.

5. Aerate your lawn

Aerating a lawn promotes healthy grass roots and growth, and decompacts soil, which in turn discourages weed growth. You can aerate with spikes or plugs (see below).

Aerating before fertilizing will give your grass an even better chance of thriving, but if weeds are a problem, consider a fertilizer/weed killer combined. You can use a spreader (see below) to do this last part of the job evenly and efficiently.

6. Use a specialized weed killer

'If you are going to go down the route of using a weed killer to get rid of weeds on your lawn, make sure you opt for a specific lawn weed killer,' says Ruth Hayes, gardening contributing editor on Homes & Gardens. There is a range of weed killers on the market, including several homemade varieties such as weed killers using vinegar and Epsom salts, but many are not suitable for use on otherwise healthy grass.

'Using a general-purpose weed killer will kill the grass as well as any weeds, and ruin your lawn in the process,’ Ruth continues. ‘Weed killer is either combined with a moss killer and lawn food or as a stand-alone product,’ she adds.

‘Selective herbicides are designed to kill specific types of weeds while leaving the surrounding grass unharmed,’ continues David Angelov or Plant Parenthood. ‘Look for a product that is labeled for the specific types of weeds in your lawn and follow the instructions carefully. There are different chemical concentrations for broad-leaf weeds vs narrow-leaf weeds.' A good option is the Ortho weed killer for lawns, available from Walmart.

'It’s important to apply herbicides when the weeds are actively growing and the temperature is not too hot. I recommend doing so in the spring or fall.’

Ruth Hayes

Ruth Hayes is an expert gardener, and formerly gardening editor of Amateur Gardening magazine. She is horticulturally trained, with a qualification from the Royal Horticultural Society, and now regularly shares her expertise with Homes & Gardens.

FAQs

Will vinegar kill weeds but not grass?

Vinegar is a strong acid which will kill the weed, and any plant matter (including grass) around it. When using vinegar to kill weeds, ensure it is not in an area you want to preserve, and that the vinegar only touches the weed you are trying to treat.

Does boiling water kill weeds?

Boiling water will kill any area of a weed it comes into contact with, but will not kill the roots, leaving the weed to return within a few weeks. As a result, it is not advised to use plain boiling water as a weed killer – especially in areas of your yard surrounded by grass.

Now you are fully armed with all the professional advice on how to kill weeds but not grass, you can discover what needs to be on a spring lawn care checklist, and ensure your lawn is lush and healthy all year long.