November 6, 2019

Modest Success in Controlling Wiregrass

In my last blog post, 5 Principles of Soil Health: In the Garden, I mentioned some success in my ongoing battle with wiregrass. If you've read my blog for any length of time, you've likely heard me rant, whine, rage, complain about this problem. It's "real" name is Bermuda grass.

Cynodon dactylon. Indeterminate. Spreads by seed and stolen.

It's a popular lawn and pasture grass in my part of the country. It's ubiquitous—there's nowhere that it isn't—because it's heat and drought resistant, plus tolerates heavy traffic and mowing (or grazing). But it has a dark side: it's highly invasive and quickly becomes an extremely tenacious weed. It has a number of other names, but earned this nickname because it's tough as wire when you're trying to pull it out.

It's also impossible to get rid of. Even the "experts" admit that and at some point the southern gardener simply has to accept it as a fact of life and learn to live with it. It's the reason why we tilled for so long in the garden. Its roots choke out everything and become a compacted barrier to the soil. Dan would till and I'd rake out as much as I could before planting, in hopes of getting a harvest before the wiregrass took over.

All of that is to preface my "success," meaning I have by no means conquered wiregrass, I've merely managed to keep it at bay for the past year in some parts of my garden. Let me show you.

These are the swale beds I made last winter.


They were double dug to create swales in our clay subsoil, filled with organic matter of all sizes (tree limbs to twigs) layered with topsoil, woodchips, and compost. The goal was to not only improve the soil in the beds, but to catch and retain rainwater in the swales. (Details here.)


Between the beds I laid down cardboard and paper feedbags covered thickly with wood chips.

Walking aisle between two beds.

The miracle is, almost a year later, they haven't been taken over by wiregrass! I usually expect the wiregrass to regain control by late summer or early autumn.

So what's different here than in other parts of my garden? I know from years of experience that mulch alone will not keep wiregrass at bay.

Wiregrass happily growing up through a thick layer of woodchips.

Case in point - my asparagus bed. Actually, I gave up on asparagus several years ago. I kept having to relocate it because of wiregrass, and finally gave up. I covered the entire bed with a thick layer of woodchips and called it quits. But the asparagus was persistent and made a surprise showing this year. Trouble is, so did the wiregrass.

Asparagus on the left, competing with wiregrass &
blackberry vines. On the right, a walking aisle with
cardboard tucked under the border plus woodchips.

So what do these areas have in common? Firstly, there was a lot of trampling while double digging. Not much survived that. When the soil was dug and set aside, I removed all traces of wiregrass stems and stolens. Third, I didn't mulch the aisles with only leaves or chips; I put down a barrier - in my case cardboard and then a thick layer of mulch. These are the areas that have remained wiregrass free so far.


What I'm going to have to address for continued success is the main pathways down the length of the garden.

One of two large aisles. The black pipe is
for greywater drainage when we need it.

The main aisles get mowed but also can become overgrown quickly. The edges between these and the mulched aisles is where wiregrass reintroduces itself. It's those edges where the wiregrass sneaks back in.

Wiregrass creeping into a heavily mulched area between two beds.

I've got my winter's gardening project cut out for me. I hope to make two more swale beds, plus cover the main aisles with heavy cardboard and chip mulch. Hopefully, the weather will cooperate!

Is this a permanent solution? No! It will require diligent maintenance to stay on top of it. But after so many years of feeling like I'm fighting a losing battle, any reprieve is very welcome.

17 comments:

Ed said...

I am thankful that I live north of the Bermuda Grass Line!

Fiona said...

We are dealing with Johnson grass in our gardens. It has rhyzome sections 4 to 5 feet long and can spear its way through landscape fabric. Our approach is trying to dig as much of it up as we can and carefully remove the rhyzomes. It is working in the east garden, albeit slowly but has had no noticeable effect in the west garden. When cut young it is very good hay😳
I am trying to convince Ralph to buy industrial landscape fabric for the west garden. We had looked into Bermuda grass to top seed one of our new paddocks because it is tough.
I so enjoy your approach to problems, I always learn from your Blog👍👍

J.L. Murphey said...

We have neither Bermuda nor centipede grasses on our property. We just have every other kind of invasive weed.LOL

But I remember battling the St Augustine grass at my old homestead. My youngest was allergic to it and all my neighbors had it too. We dug down two feet along the perimeter of the property (an acre)deep enough for a cinder-block and then stacked them two high. We didn't till it under. We pain painstakingly cut 2-foot wide long strips and rolled it up as a carpet. This way we got rid of ALL the roots, runners, and seeds. We also religiously cleared the cinder-blocks every three months. We actually sold the rolls to a landscaping company.

It sounds drastic and it was. But how many times would you want to rush your child to the ER because her airway was swelling to have them tube her and put steroids into her lungs to keep her alive. She was a kid who couldn't roll in the grass or even walk on it barefoot. That's how we solved our Bermuda/centipede grass problem.

Goatldi said...

Ahhh now I know what wire grass is. Bermuda is very popular in CA also as it is an inexpensive and tough lawn. We get Johnson grass too. Just as tough and easily spread. One needs to be very careful of where one gets any fill dirt. Even when purchased in bulk from a soil / gravel excavation outlet there seems to be two types. One which is not clean and could bring in the bad stuff. And one that has been “sanitized “ no bad guys yeah. Downside a very sterile product. Remember when dirt was dirt and the playing field was more level?

Good work to eradicate the problem.

Leigh said...

Ed, consider yourself lucky! Although it seems most gardeners deal with one kind of invasive grasses or another.

Fiona, we have Johnson grass too, but it's only in a very small section of the garden. Like you, I try to dig the rhizomes but the rest I cut and dry for hay (the goats love it). It doesn't seem like commercial landscape fabric stops anything. We had a terrible experience with it and I'm still picking up bits and pieces that we had to till to remove. I didn't know they had an industrial "strength" but personally I'm dubious! A couple decades ago black plastic was the rage for landscape weed control. I've lived in two places where previous owners put it down and years later what a mess. So I'm also picking up bits of deteriorated plastic around the yard!

Jo, wow. That's a heavy-duty solution! Amazing that it worked, but good for you. Allergies are motivating. Glad to hear you don't have Bermuda! I guarantee you don't want it!

Goatldi, I have a little Johnson grass in the garden, but it's not as problematic as that! I know it's another invasive species in some areas. At least the goats eat the little I have, unlike Bermuda. They'll grab a bite or two, but really prefer other forage.

Sam I Am...... said...

Hat's off to you! That is amazing! I am giving up and taking out my stones this winter and mowing the area that I cannot control at all. I had no idea about Bermuda grass when I came down here. Another good reason for moving back North! LOL!

Leigh said...

Sam, I know! There's no way to have a naturalized area with wire grass. It completely takes over. So much for aesthetic rock gardens.

Hill Top Post said...

We fertilize Bermuda grass in the fields and pastures and fight it in the gardens. I have had good luck with cardboard first, compost second, and mulch third. I don't know what's going on under there now, but there's been no Bermuda for two years. I'll add more compost in the spring.

Leigh said...

Hill Top Post, do you grow a hybrid Bermuda in your pastures? I'm pretty sure mine is not, which would explain why the goats don't think much of it. A number of years ago I observed that it doesn't grow well in shade. I had the least amount in my beds of taller growing plants: tomatoes, peppers, marigolds, sweet basil. The cardboard helps for sure, which I think is why I still have a terrible problem in my asparagus bed. As perennials, I can't cover them thickly with cardboard 'cuz I don't want to kill them. The wiregrass is sneaky in that it pokes up hugging the perennials and takes over from there! :(

Rain said...

That's great that you've figured out how to manage that evil grass! I hope you continue to have success. I like the walking aisles you put in. Too bad you had to give up the asparagus, for now!

Helen said...

I hate this stuff. I don't mind in the yard (and it is one of the few that does well with the summer heat), but when it goes under a sidewalk to try and establish a beachhead in the garden...no. Each year I spend part of an afternoon trying to get down as deeply as I can in that one corner and get every bit I can. So far this year was the first time I didn't have to 'get after it'. I feel your pain.

Leigh said...

Rain, it will take some diligence to keep on top of it! It's a warm weather grass, though, and is usually still dormant when asparagus starts to send up shoots. So if I pay attention, we might get a few meals with asparagus this year!

Helen, it has certainly earned its name of "devil grass!" I've found the roots up to 12 inches underground, which only adds to its invasive tendencies. The only place we don't seem to have it is the front yard!

Toirdhealbheach Beucail said...

It is a problem here too Leigh. My garden beds started without; the only way I have managed to combat it is by staying completely on top of anything I see and managing it around the edges of the beds.

Gayla said...

Try rock salt on asparagus. The elderly ladies I take care of, told me this works. Mine is a mess so Im giving it a try

Leigh said...

TB, it's a tough one to deal with. Takes a lot of the joy out of gardening!

Gayle, rock salt? Hmmm. I thought salt killed everything! But maybe not asparagus. I'm going to have to look into that!

Chris said...

Hope you continue to have success. More experiments to develop further. Do you know what kind of woodchips you used? Like Walnut? Some tree bark, has an allelopathic effect, after they've been chipped. Takes several years for the fungi to break down the chemicals, then plants can grow on that ground again. So wondering if the kinds of chips, have made a difference too.

Leigh said...

Chris, our woodchips are mostly oak, with some sweet gum, poplar, maple, crepe myrtle, ligustrum, magnolia, and a little cedar. As much as I like walnuts, I decided not to plant any for the reason you mention. We had a black walnut many years ago, and the bit of garden getting its shade did poorly. I'm not sure about the others, except that cedar repels moths. I keep sliced rounds of it in the cat food and goat chow.