Remove Bermuda Grass in the Garden without Herbicides

I am not sure if any aggressive invasive weed can be totally eradicated. However, it would make any vegetable gardener very happy to wipe out the World's Worst Weed: Bermuda Grass. This awful grass can lock itself as a tangle of roots in your garden soil, slowly covering your entire garden bed if not restrained.  Not wanting to poison the garden in the process, this post will detail effective removal of this plant using non-herbicidal processes.

Bermuda grass invading upon Missouri Maiden Bush

Contents

Identification of Bermuda Grass

About Bermuda Grass

1 Cardboard and mulch

2 Control the boarder with an edger

3 Consider boiling water

4 Control the boarder with a weed scorcher

5 Edge control with desirable aggressive plants

6 Plastic Sheeting

7 Keep up with regular weeding

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Bermuda Grass ID

A great place to identify annoying weeds in your garden is through the Missouri Extension Weed Id Guide. If you have an idea of what the weed is, you can look up the weed topically, but you can also use their weed id key if you have no idea what you are looking at. 

When using the key, if you are unsure of the structure, leave that question to "don't know", and that will add more results to the search query at the end. Generally, each result will have a summery of a specific weed, including a paragraph that distinguishes it from other similar species to help narrow down the options.  

Also, so long as your results are narrow, I would suggest keeping the habitat question as "don't know". For this key, I have found when a weed naturally overlaps in habitats (such as turf grass, landscape, and garden), the weed in question does not always show up in all three queries. 

For example, the first query result that was noticeably similar to the invasive weed growing in my garden was Nimblewill, described in the summary page as similar to Creeping Bentgrass, which are both identified by a small, thin growth of plant tissue between the plant stem and leaf, called a  ligule, at the base of the leaf stalk. However, while I could find tiny hairs at the base of the leaf, I could not see any tiny ligule there. 

When I switched the habitat question from "turfgrass/lawns" to "landscapes", Bermuda Grass popped up, which is distinguished by a fringe of hairs at the leaf base with no ligule, clearly describing the plant in my yard.

You may need a magnifying glass to find some of the structures. Since I don't have one, I use my binoculars upside down, which works just as well.

Use the binoculars upside down as a magnifying glass.

Note that all three of the plants mentioned look very similar and basically spread in the same way. If you don't quite get the id right, it's no matter, they all are removed using the same methods.

Characteristics of Bermuda Grass

Chances are if you are reading this, you know Bermuda grass is obnoxious. Since it has three methods of invasion, Bermuda grass can easily take over the garden if not properly managed. While it sometimes invades the garden by seed, its creeping habit is more nefarious. The weed loves bare ground, so it will begin to form a colony right at the edges of the garden. It gradually then steals into any bare garden soil through its stolons above ground as well as rhizomes below. 

Bermuda Grass edges into my mulch.

The plant is a sun-loving plant that loves to cover bare soil. At each node along the stolons or rhizomes, the roots are planted and new flat short, grass-like leaves shoot out. As it creeps along, it forms dense colonies. A warm season perennial, it becomes brown and dormant in winter.  

However, it's a survivor: Bermuda grass can live after 6 or more weeks of sun occlusion.  It is also drought resistant, and when the ground is dry, its root system locks up the ground around it, making it nearly impossible to remove.

However, there are ways to manage Bermuda grass so that it doesn't take over your garden.

1 Cardboard and mulch

I am a big fan of the Ruth Stout Method of gardening, as described in her book  Gardening Without Work. She basically used tons of rotted hay mulch to cover her garden beds. Over Bermuda grass and all other weeds, she piled a 6" cover of hay¹. The Bermuda grass leaves may reappear again after a month or so, and she would add another inch of mulch where she saw new leaves. The basic idea is to continuously block the plants photosynthesis processes by occluding the sun. 

To this process, I add a layer of cardboard below, as I am not always able to get enough mulch to cover the weeds (rather than purchasing mulch, I use what grass I can get from mowing our nearby field). When the weeds appear a month later, I diligently pull off the mulch layer, and I am able to pull out the weakened plant. Then I put the mulch back into place.

Place cardboard over weeds. Then add mulch.

2 Control the Border with an Edger.

Since most weeds enter the garden at the edges, the biggest war will be at the boarder of the garden. For most weeds, simply edging the garden barrier should do the trick, but I also tuck cardboard in the edge as an added barrier to the Bermuda grass rhizomes under my fruit trees. 

You can find a highly rated edger on Amazon linked here. This one is better rated and has more reviews than the edger I own. To save money, you could use a similar tool that has multiple uses in the garden. It is one of my favorites: The Root Slayer. I prefer the root slayer for edging in my soil, which has a lot of clay and is often compacted. There are several different designs and heights. I also use it to dig holes and divide perennials.  Click here to view the model I own on Amazon.

The edger can be used to cut weeds at the garden boarder. 

For garden beds on which you really don't want to spend much time, try a more permanent edging, such as bricks. At the old parsonage, we had a plastic edging with a curved top, similar to this one, that worked very well for keeping weeds out. Since the edging was level with the ground, it was easy to mow over to prevent weeds from growing over the barrier.

3 Consider Boiling Water

Whenever I have a pan of boiling water to discard (such as from hard boiled eggs), I pour it over any spot at the garden edge where the colony is established, effectively killing the plant in that location. Obviously, care should be taken not to boil plants wanted alive, and not to accidentally pour or spill this water on any person during transport. Yes, I am mentioning that because I have spilled hot water on myself. Ouch!

4 Control the Border with a Weed Scorcher

Speaking of boiling water, a method I have not tried but peaks my interest is weed scorching.  This idea came to me from Eliot Coleman's "The New Organic Grower." Mr. Coleman remarks that the weed should be scorched for 1 second, and is terminated if the leaf shows a dark green fingerprint when pinched².

Just using my imagination, I would hesitate to use this method on mulched soil, but would be interested in using it where colonies had formed at the edges of my garden. Since Bermuda grass survives with underground rhizomes, I suspect a few treatments would be necessary each summer.

I did see some weed scorchers on Amazon. These were not terribly expensive, and I have linked to one that has a lot of reviews and currently has a good rating, the Propane Torch Weed Burner. Click here to view this product. I think this would make a pretty cool Dad gift.  

5 Control the Border with Desirable Aggressive Plants

Since Bermuda Grass creeps around in search of bare ground, create a living wall at the gardens edge to hide the bare ground. I am not advocating here to replace one invasive plant with another, but I am suggesting to transplant perennials that are themselves quite aggressive at the garden edge.  For example I have found sage and yarrow are quite comfortable in my garden for this purpose. Purple poppy mallow also works really well. It has a lovely mounded habit throughout the year, but in early spring and summer it expands outward, making a very effective ground cover at the garden edge. 

First year sage, planted at the garden's edge near a colony of Bermuda grass.  

6 Plastic Sheeting

If the Bermuda grass in your garden beds are out of control, you can also kill them through plastic sheeting. There are two methods, one is occluding the sun through black plastic sheeting. The other uses clear plastic to solarize the ground.

I have been able to significantly reduce and weaken Bermuda grass using the occlusion method and black plastic sheeting. This stops photosynthesis from taking place and prevents the weed from creeping towards sunlight. It takes about six weeks of occlusion to sufficiently weaken the plants for manual removal. 

They will grow back, however, if given the opportunity.  These weeds are pretty aggressive and can stay dormant for a long time, so cover the area with mulch directly after removing the black plastic.

A faster method would be to use solarization, which uses clear plastic in summer to trap very hot air over the ground. I did not realize that clear plastic is more effective heat trapper than black plastic. However, Eliot Coleman effectively kills weeds in as little as three weeks within his greenhouses. Coleman recommends removing the sheeting when the soil reaches 145º Fahrenheit at 2 inch soil depth³.

My son plays in the section where I terminated a cover crop and a section of Bermuda grass (circled) with black plastic.

7 Keep Up With Regular Weeding

Hopefully, after mulching, very few weeds show up. However, where they do show up, it is important to regularly visit the garden and take time to remove them or add mulch overtop of them. 

Weeding Bermuda grass by hand in dry soil, especially if it is clay or compacted, is often very difficult, as the weed's root system seems to further cement the soil together. I prefer to weed it out after a rain when the soil has some moisture in it. If I have to weed it when it is dry, I use the Root Slayer. Weeding in the morning or on a cool and cloudy day is also preferable.

Remember to enjoy life's little things, and don't get too overwhelmed with this annoying weed. It can be effectively controlled using the methods listed here.

Cardboard is the world's best toy and can be recycled in the garden.

1. Ruth Stout, "Gardening Without Work" (New York: Devin-Adair Company, 2020) 67.

2. Eliot Coleman, "The New Organic Grower" (White River Junction: Chelsea Green Publishing, 2018) 149.

3. Eliot Coleman, "The New Organic Grower"  (White River Junction: Chelsea Green Publishing, 2018) 150.