Killing grass in the vegetable garden

by Stephanie Suesan Smith on May 11, 2011

One of the biggest frustrations in a garden is how fast grass can invade and take over.  This is especially true in a new garden when you have just tilled the existing grass under and planted on top of it.  The grass comes back with a vengeance.  Saving your garden requires a lot of work, but can be done.

Grasses have hollow, segmented stems.  They range from bamboo, which can grow several inches a day in good conditions, to Bermuda, which is usually the offender in our vegetable gardens.  In any case, there are three ways to get rid of the grass.  The first one, pull up every piece, roots and all, is very labor intensive and almost impossible to achieve.  It is, however, organic and works if you really do get all the grass pulled up.

The second method is to put clear plastic over the ground and weigh the edges down with rocks or something heavy.  Leave the plastic down for a month or two to bake all the weeds from the heat of the sun.  This works best during the summer.  Doing it in August in Texas will cook anything.  This method is also organic.  The downside is you have to leave the garden fallow for a month or two in order to cook all the weed seeds laying there.

The third method is to use a herbicide.  Some people do not use herbicides because they believe they damage the environment.  If you want a quick kill, however, herbicides will do that.  The standby herbicide is Glyphosate, sold as Roundup™.  It kills weeds and grass.  The down side is it kills vegetable plants, too.  That means you either have to use it before planting, to kill out the existing grass, or use it very carefully by just treating the grass.  This is very labor intensive.

To use glyphosate to kill grass, you must wait until the soil temperature is at least 60-65 degrees.  Then you spray the grass to wet it.  The grass absorbs the poison, and transfers it to the roots.  The poison kills the roots.  This takes about two weeks.  For very thick grass, you may have to apply a second spray at this time to kill anything the first spray didn’t get.  At this point, you can till the dead grass under and use it as organic matter to help the soil.

Grass is hard to control in a garden.  Any way you go about it is labor intensive and not much fun.  However, once your patch is truly grass free, you will have a much easier time keeping weeds from coming back and smothering your vegetable plants.


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{ 13 comments… read them below or add one }

Ivin May 11, 2011 at 5:18 pm

It’s winter here and the cold is killing the grass for sure. At least I don’t have to mow the lawn for three months 🙂
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Stephanie Suesan Smith May 12, 2011 at 6:52 am

It never quite gets cold enough here for the grass to stay dormant, so some mowing happens all year round. But it is down to once a month or so in the winter.


Joan Lambert Bailey May 11, 2011 at 8:25 pm

I found that a really effective way to kill grass is simply to smother it with thick sheets of newspaper or cardboard then topped with composted manure, leaves, etc., removes opportunity for growth and the bed can be directly planted. Glyphosate is risky stuff. The surfactant it contains is deadly for frogs or other reptilian critters living in or around the yard and garden. And heaven knows those frogs arrive in the most unlikely of places when you least expect them!


Stephanie Suesan Smith May 12, 2011 at 6:51 am

What you describe is called lasagna gardening and is indeed very effective. All pesticides, and herbicides are considered pesticides, carry risks. Whether the risks outweigh the benefits is for each person to decide.


jerry from duckweed July 16, 2011 at 3:56 am

I have used the newspaper method myself many times to kill weeds. Passed down from my grandfather who did it for years in his gardens.

Cheap and effective, cant beat that.
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Stephanie Suesan Smith July 16, 2011 at 5:44 am

Cheap and effective is hard to beat, isn’t it?


Ben from Green Powder May 12, 2011 at 9:23 am

Weeds are the worst, especially grass. I tilled and planted a garden for a neighbor who was getting too old to do it herself a few years back. I have much more respect for gardeners now 🙂 Pulling up weeds and grass was almost endless. Thanks for the tips.
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Stephanie Suesan Smith May 13, 2011 at 7:09 am

Tilling grass just encourages it. You have to kill it before you till.


Ben from Green Powder May 13, 2011 at 10:55 am

Haha, that’s the same thing she said. I just went to town with the tiller before she had the change to stop me. Man it was brutal. I wish I would have read this article before hand 🙂 Won’t make that same mistake again.
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dedicated website hosting May 12, 2011 at 9:42 am

Thanks for these suggestions, last summer my garden was also caught in this infectious disease ..than i cut them all out but now thanks to you for this information
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Stephanie Suesan Smith May 13, 2011 at 7:08 am

Grass will quickly overwhelm your garden, that is for sure.


Lachlan Reid September 2, 2012 at 6:14 pm

I have some established plants that I don’t want to kill and the grass has grown heavily around them, do you have any advice on the best way to stop the grass as I know if I pull it out it will just grow back worse and if I poison it will kill the plant. I am wondering if using news paper around the plant might be the best approach.


Stephanie Suesan Smith September 3, 2012 at 6:50 am

There is a pesticide called Poast that just kills grass. I do not know how it is labeled for Australia, or if it is available there. You might consult your local extension agent as they can probably tell you what to use.


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