Sumo Gardener

How to Kill Grass in Flower Beds

While grass looks wonderful as a neat and lush lawn, it can be a real problem plant when it gets into flower beds!

Our helpful guide on how to kill grass in flower beds covers a range of different methods that will help keep your yard tidy and thriving.

How to kill grass in flower beds

How To Kill Grass in Flower Beds

While grass looks wonderful as a neat and lush lawn, it can be a real problem plant when it gets into flower beds!

Our helpful guide on how to kill grass in flower beds covers a range of different methods that will help keep your yard tidy and thriving.

Using A Flower Bed Weed Killer

The easiest and often most effective method to kill grass in your flower bed is to use a broad-spectrum herbicide.

You can typically find this at online or any local garden depot, and it comes in a liquid concentrate or as a premixed solution that is ready to use.

In addition to killing grass, it is also an effective flower bed weed killer, so you can use it on any weeds that appear through the season.

It’s important to use this option as a last resort. Many weed killers for flower beds have very dangerous chemicals in them, which is why you need to wear protective clothing.

These chemicals are harmful to the environment, pets and children, so they should be avoided where possible and only used under safe circumstances.

Here’s how to safely use weed killers for flower beds:

  • Choose a day that when there is little or no wind, and when it is unlikely to rain for at least 24 hours.
  • Put on protective clothing. Wear old yard clothes and rubber gloves. You can also wear protective eyewear (sunglasses work just fine) and a mask or old scarf around your mouth.
  • Apply the herbicide carefully to the entire plant. Herbicides with a wand sprayer work the best because they limit overspray.
    Be very careful not to get this flower bed weed killer on any other plants, as it will kill them too. You can use a piece of cardboard to help shield them if the grass or weeds have grown up close to other plants.
  • Wait a day or two and check the grass. It should be turning yellow and dying. If not, you will need to reapply the herbicide.
  • Once it is dead, dig it up and throw it in the waste bin. Don’t put it in your compost, as the herbicide is still dangerous to other plants.

Using Herbicides to Kill Grasses and weeds in your gardens

Selecting Herbicide Weed Killers for Flower Beds

A better option is to use a selective weed killer for flower beds. Although these still contain harmful chemicals, they shouldn’t harm your other plants and work on almost all types of grasses like crabgrass, nimblewill, quackgrass and foxtails.

If you have a nutsedge infestation (identifiable by the small tubers in the roots), you will need a nutsedge-specific herbicide. You can apply these herbicides the same way you would a broad-spectrum herbicide.

Using Pre-Emergent Weed Killer in Flower Beds

Want to know how to kill grass in flower bed before it even starts growing? A pre-emergent herbicide will kill grass seeds that have landed in your flowerbeds, preventing them from growing.

This is especially useful if you have seeding grass that has gotten out of control. This type of herbicide won’t affect growing weeds and grass (or the rest of your plants) as it only targets seeds. 

It is a broad-spectrum seed killer, however, so don’t use it where you have planted seeds you wish to propagate.

How To Kill Grass in Flower Beds Organically

Because of the harm they do to the environment and the risks to your health, your family and pets, we do recommend that you use alternatives to these dangerous chemicals. Here’s how to kill grass organically.

Using Newspaper

How to kill grass in flowerbeds using a newspaper-based sheet composting method:

  • First, lay down sheets of newspaper over the unwanted grass, making your layer 4-5 sheets thick. 
  • Water the newspaper well. This will help weigh it down, so it doesn’t blow away. 
  • Add a thick, 3-inch layer of mulch over the newspaper. You can use any mulch or compost on offer from your local garden center or you can make your own compost.
  • The darkness and wet will kill the grass and the newspaper will decompose into the flower bed, adding nutrients. The whole process may take about a week but it’s faster if you keep the mulch and newspaper wet.
  • Simply pull out any grass that survives.
  • This is a good method to apply before the grass starts to seed, as it will kill the growing grass. It will leave seeds unaffected, however, and these may still sprout.

    If this happens, either pull them out as they appear or repeat the newspaper process.

Using Boiling Water in Your Flower Beds

Using Boiling Water in Your Flower Beds to kill grass and weeds

Boiling water is very effective at killing grass and weeds, and it’s pretty effortless too! Here’s how: 

  • Boil water and pour it onto the grass that you want to kill. This method is indiscriminate, so don’t let the boiling water touch any other plants.
  • Watch the grass, as it should turn yellow and die.
  • The roots may be unaffected with just one round of boiling water, so repeat this process two days after the initial treatment.

Using Vinegar or Salt Solution

Use Vinegar solution or salt solution as a grass killer in your flower beds

Household vinegar is another great organic flower bed weed killer that works very well on all types of invasive grasses. The acetic acid in the vinegar dissolves the cell membranes of plants, so they dry up and die.

It’s safe for you and the environment, inexpensive and easy to use.

Vinegar Recipe 1

For the vinegar and liquid soap solution, mix one ounce of liquid soap per gallon of vinegar. 

Vinegar Recipe 2

Another popular mix is 1lb of salt to 1 gallon of vinegar with 1tbs of dishwashing liquid. 

Here’s what to do:

  • Buy vinegar from your local store. Any normal, cheap vinegar will do. You’ll need about half a cup per plant or enough to soak the area you want grass-free up to about 1-inch deep in the soil. You can also buy horticultural vinegar, which has a higher level of acetic acid.
  • Fill a spray bottle and adjust it to “stream” rather than “spray”.
  • Spray the grass or weeds, and avoid spraying any other plants or they may be harmed.
  • Watch the grass as it should turn yellow and die after a day or two. Repeat in a week’s time if the grass has not died.
You can also combine household vinegar, dish soap, salt and water as an alternative solution, following the same application method as above.

Using Solarization and Plastic

Too much sun and heat can kill grass, and this method allows you to use the sun to organically kill unwanted grass and weeds.

It’s especially effective on larger areas, like new or overrun flowerbeds, and is one of the best flower bed weed killers. Here’s how:

  • Although you can use this method any time of year, it’s best to choose a time of year that is hot and sunny without much rain.
  • Cut the lawn as short as possible in the area where you want the grass or weeds removed.
  • Irrigate the area well. This helps raise the temperature once the plastic sheeting is in place.
  • Cover the space with a 2-4 mil plastic sheet, the kind you can get at any home improvement store. Black plastic works well but even clear plastic will do. Try to cover a bit beyond the borders of the space you want cleared. You can overlap sheets if needed, just remember to leave no gaps.
  • Anchor your sheets down with rocks.
  • Leave the sheets in place for 6-8 weeks without watering the area. You can start clearing dead grass away 1-2 weeks after the grass has turned brown.

This method is a little time consuming but is very effective and safe for the environment! You can make the process faster by double-layering your plastic sheeting.

Pulling Out Grasses in Your Flower Beds

Pulling Out Grasses in Your Flower Beds with all of the roots

A slightly more labor-intensive job is to pull out unwanted grass by hand. This works well in small problem areas or where you have removed grass and simply want to maintain a flower bed by controlling the small amounts that unavoidably grow each season. Here’s how:

  • Use a small garden spade or trowel.
  • Start weeding and removing grass when the soil is wet after rain or being irrigated.
  • Dig around the grass clump and remove with the roots intact, without shaking the grass and potentially spreading grass seeds.
  • Dispose of in a bucket that is emptied into the trash and not the compost bin, as this will allow grass seeds to grow.
  • Repeat each week through the growing season in order to remove grasses before they start seeding.

You can also use a small tiller to help remove weeds and grass, and prepare flower beds for planting.

Using Mulch to Suppress Grass

Using Mulch to Suppress Grass from growing in your flower beds

You can also suppress the growth of grass by adding mulch. For people who don’t know, mulch is made out of materials that are decaying, including dead leaves and as well as compost that is generously spread along the soil's surface to enrich or insulate the oil.

Now, once you have removed almost all of the grass, the next thing that you can do is to cover the soil with a thick layer of newspaper and place at least 4 inches of your chosen mulch. This process will kill the grass since the air and light will be blocked from penetrating through the soil.

Using Common Plants To Prevent Grass Growing

growing Basil in flower beds is a natural repellent for grass

You can also start growing plants that can act as the garden's natural repellents, such as crown imperial, citronella grass, basil, and bay leaves.

These are some of the tips on how to kill grass in flower beds. Of course, preventing these grasses from sprouting again is also essential. Get to know how with a few tips below.

Preventing Turf and Grass from Spreading into Flower Beds

As with most things, prevention is better than a cure! You can help prevent unwanted grass and weeds creeping into your flower beds by:

Installing Edges On Your Flower Beds

Installing Edges On Your Flower Beds to prevent grass entering

The best way to prevent the grass from growing again is by installing some edges around the flower bed. Check out 65 Lawn and Flower Bed Edging Ideas.

Dig a Trench Around the Flower Beds Edge

Dig a Trench which will be like a moat around your flower bed

  • Digging a trench around your flower best and inserting a barrier of edging material, like bricks, wood or plastic edging. This will need to be sunk to 8 inches deep and sit 2-3 inches above the soil height to form a good physical barrier.
  • Mulch your shrubs well with a layer of 2-4 inches deep each year. This will prevent weed and grass seeds from sprouting by depriving them of sunlight.

    You can use bark, wood chips or pips. Remember not to stack this against the stems of your other plants, as this can cause rot.
  • Water your plants deeply and less often. Grass roots are shallow, so they thrive on frequent watering, while most of your shrubs have much deeper roots.

    Rather than watering every few days, water only once a week and be sure to water well. This will support your established shrubs but make a less friendly environment for any grasses.

Keep your lawn trimmed and healthy. Frequently mowing your lawn will help prevent it from seeding or creeping into your flower beds. Mowing prevents the grass from developing flowers which turn into seed heads. 

Mow once a week if you have fast-growing turf and once every 10 days to two weeks for slower varieties.

Related articles:

Mowing Your Lawn to control your grass and prevent growth in your gardens

Now You Know How to Kill Grass in Flower Beds!

Now that you have all the different methods of how to kill grass, along with their pros and cons, you can choose the best flower bed weed killer and grass killer method that works for you!

With this easy guide, you have all the information you need on how to kill grass in flowerbeds in order to achieve the perfect grass-free, neat flower beds your home deserves.

How to kill grass in flower beds

About the Author Ann Katelyn

I'm Ann Katelyn, Creator and Chief Author of Sumo Gardener. Since I was a child I've always been fascinated with plants and gardens, and as an adult this has developed into my most loved hobby. I have dedicated most of my life to gardening and started Sumo Gardener as a way to express my knowledge about gardening with the hope of helping other people's gardens thrive.

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Leave a Comment:

Angie Jensen says May 15, 2020

Hi…. What a great summary of killing weeds etc…. Simple to use and simple to understand.
One tip I have especially for weeds amongst heavy planting is to cut both ends off a food can and insert over the weed to be killed… Making sure of course that there are no parts of plants under it, then just spray inside the can with whatever option you want….. Make sure that when you lift the can that spray doesn’t drip down the can onto plants around it….. Works for me…… Thankyou… Will read your other posts 🥇

    Ann Katelyn says May 15, 2020

    Hey Angie, Thank you for such a great tip.

Joann says June 6, 2020

What is the ratio for using vinegar and liquid soap for weed killer? Interesting article.

    Ann Katelyn says June 9, 2020

    Hey Joann,

    It is the acetic acid in vinegar that kills weeds, so the more vinegar you use, the more effective your mix will be as a weed killer.

    For the vinegar and liquid soap solution, mix one ounce of liquid soap per gallon of vinegar.

    Another popular mix is 1lb of salt to 1 gallon of vinegar with 1tbs of dishwashing liquid.

    Be careful while using either of these strong solutions, as they are non-discriminating – it will kill or damage any plants it falls on, whether they are good plants or weeds.

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