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Did the Solarization Experiment Work?

Solarization is a toxic-free way to deal with weeds. Read about our experiment to determine if it would work for you!

In early summer, we solarized our front yard. You can read the full post here. By using the clear plastic to trap the heat of the sun, the goal was to essentially cook the soil, killing any weeds and weed seeds present. I was hoping this was the magic non-toxic  solution for my constant battle with Bermuda grass. So now, about 3 months later, you might be wondering, did it work?

First, let’s review how the actual solarization process went.

We spent one weekend tilling, watering, and laying out the plastic. The plan was to leave that plastic in place for 4-6 weeks. After that, my plan was to remove the plastic, and throw out buckwheat as a cover crop, which would add some nutrients in the soil and provide some cover from windblown seeds. Then, a month later (buckwheat grows uber fast), I would wack that down, then layer compost on top of that, and plant a low-water native landscape that I had designed.

Using clear plastic, we are capturing the heat of the sun to kill weeds, naturally.

Here’s how it actually went. The plastic started to break down after about 2 weeks, with tiny holes from sticks poking though, and slits appearing. We made some attempts to use duct tape to seal the splits, but more and more appeared each day. By the end of the month, we gave up.

Solarization is a toxic-free way to deal with weeds. Read about our experiment to determine if it would work for you!

The plastic only lasted about 3 and a half weeks, not nearly the 6 weeks I had hoped for. It was still too early (ie, middle of summer and therefore f’ing hot) for me to throw out my cover crop seeds, so I went with my next best option for covering up the soil. My dear friend, cardboard.

Solarization is a toxic-free way to deal with weeds. Read about our experiment to determine if it would work for you!

I reformatted my plan (you have to be flexible with plans when you’re dealing with gardens). I would cover the space with cardboard, leave until late September, however ugly it might be, but it was both shading out any potential weeds and preventing traveling seeds to sprout. Then, I’d spread a layer of horse manure, throw out winter cover crop at the end of October, then plant my native low-water landscape in the spring.  As I pulled away the shredded plastic, I would lay out sheets of cardboard. It took about a month of weekend trips to the furniture store, bike shops, and appliance store dumpsters to get enough cardboard to cover the area we solarized. I used large pieces, and made significant overlap, to prevent spaces for the weeds to grow back.

Solarization is a toxic-free way to deal with weeds. Read about our experiment to determine if it would work for you!

I got as far as covering the area with cardboard before finding out we were going to be moving at some unforeseen time in the near future. I can assure you that a front yard covered in boxes (at least I put them all label and text side down!), weighed down with bricks and assorted rocks, was not aesthetically pleasing. My dear neighbor from across the street kindly described it as a ‘neat modern art’ installation. I didn’t want to put out soil (expensive), but I didn’t want to pull the cardboard up (exposing ugly dead weeds and dirt). So I revised my plan AGAIN (and people think I’m not flexible….HA!) and started covering it with wood chips. This made it so it looked decent for potential house buyers, and it also created a good base for the next people to start landscaping.

Solarization is a toxic-free way to deal with weeds. Read about our experiment to determine if it would work for you!

So did the solarization attempt actually do anything?

When I pulled up the plastic, there were some tiny bits of Bermuda grass still green and growing. It wasn’t as prevalent as before, but it was still there. I pulled what I could before I laid down the cardboard, and most was easy to pull. They weren’t deep, which makes me think they were segments or seeds, brought to the surface from the tilling. I saw no signs of the other weeds, like the sow thistle or the plantain.

Solarization is a toxic-free way to deal with weeds. Read about our experiment to determine if it would work for you!

Now, a good 4 months later, with a thick layer of cardboard and mulch and we’ve had rain, I still see no signs of the ‘other weeds’. There is Bermuda creeping in from the edges, which was expected, as I didn’t go all the way to the edge of the street pavement or onto the neighbors property. I don’t see any signs of it emerging from the interior mulch. I do have, however, have bulbs pushing though, which surprised me. I had a healthy population of paper-whites, daffodils, and sporaxis that was also growing in the ‘lawn’, but I was sure that the rototiller would have chopped them all up or they would have baked from the solarization.

Solarization is a toxic-free way to deal with weeds. Read about our experiment to determine if it would work for you!

Would we try solarizing again? Maybe.

That’s what it comes down to, right? I think the plastic tore so quickly because the front gets so. much. sun. Add the reflection of the blacktop from the road, our driveway, and the house- it freaken bakes out there. The plastic expands and contracts with the heat and the cooling of night, and small sticks would poke though. If we made the plastic looser or had a softer surface it laid on, it might have done better. We put some of the plastic out in a section of the back yard that gets less sun than the front, and it didn’t tare nearly as quickly. We also didn’t till or water the soil under it, so it didn’t do much. It seemed to work great for the ‘lesser’ weeds, but not perfect for the Bermuda. So would we do it again? It depends.


Solarization is a toxic-free way to deal with weeds. But does it work? Read about our experiment to determine if it would work for you!

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2 Comments

  • Reply
    Kalamain
    November 15, 2016 at 11:24 am

    If it was a smaller area I would have tried putting down a simple tarp. Its a thicker plastic and although its opaque it should still turn the area below it into an inferno.
    BTW… Who would plant something so…. Unkillable? O.o

  • Reply
    Shannon
    November 17, 2016 at 9:29 am

    Thanks, Melissa, for sharing your experience. I’ve done exactly the same thing with horrible results, and I didn’t blog about it. I resorted to eradicating Bermuda — and Torpedo and Nutsedge — with an equally competing turf grass: St. Augustine. As a grass, it does its job of choking out everything else that will infiltrate the space from the edges. St. Augustine is easy to manage as it’s runners grow ABOVE the soil with blades shading everything else under it.

    Bermuda is a tricky beast. As grasses go, it is perfect example of why grasses own this planet. In my experience, solarization isn’t enough for this successful turf grass. It can re-establish from as deep as 18″ from any trace of stolon/root below. Tilling just makes it stronger, breaking up it’s underground runners into smaller, more easily propagated multi plants. I’ve seen it break through 4-5 layers of cardboard and as much as a foot of shredded trees (mulch).

    Torpedo was my nemesis…took more than 5 years to see it gone from the property.

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