The Great Cardboard Experiment

HEChicken

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On a previous thread, I discussed my use of VERY thick cardboard last year to try to kill the weeds in my new garden patch. This thread is an update….

On Sunday DH and I pulled up the cardboard, so that we can get the tiller in. Underneath we found that in places it seemed to have worked but in other places, the weeds were still there - perhaps dead, perhaps dormant. The cardboard itself was wet and heavy (and therefore difficult to move) due to all the snow that sat on top of it for days. Underneath, in some places it was also damp but in others, very dry. In some places the dampness had led to the bottom layer of the cardboard starting to decompose and when we tried to pull it up, that layer stayed on top of the soil. We decided to leave it there to be tilled in.

One thing we noticed is that the earthworms really appreciated the addition of the cardboard to the garden. The corrugations are the perfect size for worms to crawl into and they had used them as shelter from the elements, keeping the worms much closer to the surface than I would normally expect at this time of year. The worm castings that were adhered to the bottom layer of the cardboard in many places were also very pleasing, and we knocked as much of that off into the garden before carrying off each piece of cardboard, as we could.

I think I would, overall, give this a 3.5 star rating. It wasn't an overwhelming success but nor was it a failure. It was a lot of work both laying the cardboard out and pulling it back up. Now it is the windy season and our stack of cardboard is getting blown around a bit, so we'll have to find a way to weight it down to prevent that. DH would like to replace some sheets of it around the perimeter of the garden after the tiller has been in, to help prevent grass growing in sideways. Would I do it again? Probably not. But would I advise someone else NOT to do it? Again, probably not.
 

Nyboy

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I love cardboard I use it in flower beds. I have a friend who has a store in town, she save boxes for me. I lay them down thick and then cover with mulch. The beds that I didn't use cardboard have to be weeded much more frequently.I have never lifted it up just add more mulch every spring.
 

HEChicken

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It wasn't possible with this cardboard to just leave it in place as it wasn't your typical cardboard box flattened out. It came from commercial duty cardboard cartons - each designed to hold a LOT of weight. The cartons flattened out were about 6x8 (feet) and I originally said were the thickness of "about 5" cardboard boxes but while handling it on Sunday, I realized it was many more layers of regular cardboard than that. Had it been standard "Amazon style" cardboard boxes, I doubt there would have been anything left to pull up by now and I would have just tilled it into the ground.
 

Ridgerunner

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I’ve used cardboard covered with mulch in between my rows and along the outside edge of the garden. It works great in between the rows. I leave it on all winter and just dig it in the next spring unless it is still in a fairly big sheet. It almost never is. Those few go in my compost. I think how damp your climate is makes a difference in how fast it breaks down.


It works really well around the outside of the garden too, it really helps. But it is not a perfect cure-all. I find that my Bermuda grass will send runners under that cardboard for at least five feet and come out the other side. When you take that cardboard up you see a lot of runners under there. It still makes it a lot easier to deal with.
 

ninnymary

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HeChickens, it sounds like you should try a thinner layer of cardboard and then just till it in. I would defintely give it a try if I were you. You have anothing to lose.

Mary
 

HEChicken

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Oh, we're done with the cardboard for now - it has served its purpose. The problem with thinner cardboard is….it comes in much smaller sizes. And this is a large garden area. And it gets very windy here. I did initially try using thinner cardboard but the wind just picked it up and carried it away. I had a few bricks lying around but it took a brick on every corner to hold a piece in place and I didn't want to haul the number of bricks it would take to hold down the larger number of thin sheets - both on and off the garden again.

When the opportunity came up to get these thick cardboard cartons, they seemed ideal. Flattened out, each carton is about 6x8. Even so, it took a trailer load of them to completely cover the garden. I lost count….but we're talking 50 or more. Using the thinner, far smaller cardboard boxes, we'd have needed around 200.

So it is the scale of the thing that makes a difference, I guess. For a garden walkway, a thin cardboard box covered by mulch will be ideal. But to cover the whole garden…..I couldn't find a way to make that work.
 

thistlebloom

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I agree with your assessment HEchicken, it sounds like a terrific amount of labor for an annual garden.
I'm thinking that something like that would be ideal for a new future garden space if you layered mulch on top and had the luxury of waiting at least two years before you planted it.
 

lesa

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Some of our ideas just don't work out quite like we imagine.... I tried using old carpeting in my "back 40" area. Worked great, until it started rotting. You should see what happens when those unraveling threads get into the mower. Dh has invented some new swear words! Always up for an experiment, you just never know.
 

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