Cardboard in the gardens

TraceyOKC(7)February 7, 2012

Hi all! I am ready to embark on my 2nd year of gardening. I have learned soooo much from just reading in the forums. Thank you to everyone that shares their experiences and knowledge!

We are building 2 new lg (25 foot)flowerbeds and preping the veggie garden 15' x 23'. Last year I mulched with grass clippings. I had trouble with the bermuda grass and weeds creeping into my garden...does putting cardboard down help with that? What kind of cardboard...the thin stuff like a cereal box or the corregated layered shipping box type? Is something put on top of the cardboard? Should it be limited to just the walkways or cut out a hole for the plants? Will it work in the flowerbeds too? Pros and Cons?

DH and I have been talking this through and decided to ask the folks on the forum. :-)

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helenh(z6 SW MO)

I use it on paths and between big plants like tomatoes. I cover it with mulch or soil if I have no mulch. Sams has big sheets of cardboard that my local store will let me have. You can use it in your Bermuda fight; it only helps and is not a cure. Did you see this long thread and what others said about cardboard?

Here is a link that might be useful: suggestions for covering paths

    Bookmark   February 7, 2012 at 1:33AM
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Okiedawn OK Zone 7


We use the larger pieces of brown corrugated cardboard when we can get it. We have a pretty good-sized barn-style garage, and I have a rear corner of that garage where I store cardboard as I 'collect' it throughout the year. At our house, cardboard doesn't go into the trash. I don't just use it in the veggie garden (and my veggie garden isn't just a veggie garden, it also grows fruit, herbs and flowers) but also in shrub beds and underneath fruit trees.

In pathways and other areas with heavy usage, you can put down 2 or 3 layers of thick cardboard and layer mulch on top of it and that cardboard, even though it breaks down over the course of the season, will normally last the entire growing season. In growing beds, you can cut holes, and a utility knife (like a box cutter, for example) is great for that and plant into the holes.

In beds where you raise veggies, herbs, fruits or flowers, you might have better luck with ordinary newspaper if your plants are going to be spaced pretty closely together. For example, you can put cardboard in a bed with tomatoes, eggplant, peppers, etc. but it would drive you crazy to try to use cardboard with more closely-spaced plants like beans or peas. I just lay down newspaper 6 to 8 sheets thick in some veggie beds and layer mulch on top of it.

With some pests that like to hide under cardboard, like squash bugs, you may find the cardboard helps encourage those pests. I use a weedblock fabric in those areas, and I pin it down tightly to the soil so it is harder for the squash bugs to get under it to hide.

Both the newspaper and the cardboard serve a dual purpose. They block light to the soil (and weed seeds) beneath them. That prevents a lot of weed seeds from sprouting. Then, if weed seeds sprout in the mulch on top of the newspaper or cardboard, their roots have to work a lot harder to make their way down through the cardboard or newspaper to reach your garden soil That doesn't mean you can ignore any weeds that sprout, but it does mean that they are slower to grow so you have more of an opportunity to yank them out of the mulch before they put roots down through the cardboard or newspaper into the soil.

Both cardboard and newspaper help your garden in another way. They attract earthworms and earthworms are great soil builders.

If you use newspaper, just use the regular newsprint and not the glossy advertising pages. With cardboard, remove staples and pull off any cellophane tape if the cardboard has either before you use it.

Bermuda grass is a separate issue from many normal weeds because it is perennial and it can spread via roots, creeping rhizomes or seed. You have to aggressively remove every bit of it you encounter. The link Helen provided goes into a lot more detail about ways we all do that.

My garden is on former farm land that was heavily infested with Johnson grass (it is like bermuda grass on steroids) and it will send rhizomes under ground and travel many feet before popping up here or there. The cardboard makes it travel a lot farther looking for a bare piece of land where it can sprout upwards and grow. When I see some Johnson grass popping up out of the ground, I rake back the mulch, lift the cardboard and dig out the rhizome. Sometimes I have to travel 15 or 20' through the garden, lifting cardboard and digging up the rhizome that's been trying so hard to find a cardboard-less place to sprout. So, while it doesn't completely eliminate an aggressive grass that spreads via rhizomes, it lessens the amount you have to deal with.

With thinner cardboard like ceral boxes, I usually tear those into smaller pieces and compost them in the compost pile.

Finally, here's how I use cardboard as a soil builder. I put it down in pathways (although sometimes I use weedblock fabric instead) and layer mulch on top of the cardboard or weedblock fabric. I use all kinds of mulch, including spoiled hay or straw, chopped and shredded leaves, grass clippings, etc. I put down mulch as thick as 4 to 6 inches in the pathways between my raised beds. (I dug out the soil in the pathways originally to add to the raised beds in order to raise them higher, and that left me very deep pathways that go down about 8 inches below the original grade of the soil surface.) I add more mulch throughout the growing season whenever I can.

I stop adding mulch to the pathways in about September or October. The mulch in the pathways, of course, is decomposing all along throughout the year.

In January through March or even April, as I am planting in the raised beds, I prepare each bed for planting by using a compost scoop to scoop the former mulch, which is now compost, from the pathways and up into the beds. Then, I put down a new layer of cardboard and mulch into the pathways. To me, composting in-place in the garden paths is simple and I don't have to use a wheelbarrow to haul compost from a compost pile (which I also do have) to the garden. That saves me a lot of time and back-breaking effort. My grandfather always csheet-omposted in his garden pathways, though he didn't use cardboard and he didn't have raised beds. He had sandy soil, though, and it was fairly easy to yank out grasses and broadleaf weeds. He was just using the sheet-composting to improve his soil. I have clay, and with many weeds, I have to dig them out because if I yank them, the above-ground portion breaks off in my hand but the roots or rhizomes remain. So, I find heavy mulching on top of cardboard eliminates a lot of weeds, but make no mistake about it---it doesn't prevent them from growing. It just makes them easier to remove.

Earthworms love, love, love cardboard and newspaper, so when I am shoveling up compost out of the paths into the garden beds, I am 'transplanting' earthworms along with them. Earthworms are one of the best garden helpers around, so finding tons of them in the composting pathways is just a big bonus.

If weeding drives you crazy, you could use one of the pre-emergent herbicides that are made for use in vegetable gardens. I try to garden using the most healthy and sustainable methods possible, but every year I ask myself "why don't you just buy Preen for Vegetables and use it to cut back on the number of weeds you have to deal with?". One of these years I am going to break down and buy it and use it. I have gardened ever since I was a child, and I've about had my fill of pulling weeds---not that a gardener ever will find a way to make their property weedless.....but wouldn't it be nice?


    Bookmark   February 7, 2012 at 9:48AM
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