How to Mulch with Cardboard

As some of you may recall, our vegetable garden was in rough shape at the start of this garden season.  There were weeds and grass taking over the whole garden bed, and it took a lot to get it cleared out.  Most of the weeding was done by hand to ensure we got as many roots out as possible…if you leave the root in the ground, the root still takes in nutrients and it will most likely re-grow.

Some of you may think I’m nutty, but I refuse to till the garden, and I will NOT use weed killer in the garden.  I will sometimes make a homemade weed killer for areas like the sidewalk, but it’s not going in or near the garden.  Tilling messes with the soil structure, which won’t harm much if you only do it once in a rare while out of desperation, but it can eventually lead to soil erosion and kills bugs and bacteria that are essential to growing a healthy garden.  Plus, if you are doing either of these things, it means you probably don’t mulch, and mulching with wood chips or hay/straw is one of the best things you can do for your garden.  Mulch keeps the soil moist, it helps keep weeds under control, and it eventually decomposes and turns into more food for the garden itself.  Not only does it keep weeds from being a complete terror to your garden, it keeps the soil moist which makes pulling weeds much easier.

I’m not implying that mulch equals no weeding ever.  You will still get weeds, that is just nature at work.  The one thing you will want to be careful of is not using fresh hay or fresh woodchips.  If you get stuff that is fresh, the odds of there being weed seeds still capable of germinating are high, and you will give yourself extra weeds to pull.  Trust me on this one, I did it once, and it created a lot of extra work…on a positive note, they were still pretty easy to pull because of the mulch.

But enough lecturing!  We did as much as we could to prepare our main garden for planting as possible given the circumstances.  I has to wait to take care of the gardens because in early spring I was very pregnant and couldn’t be kneeling down, doing garden clean up, and in fall, I had morning sickness that was terribly aggravated by any heat. I knew I was going to have a lot of extra upkeep once the garden got rolling.  The real problem became apparent after we had layed our mulch and planted the garden…the grass on some of the more vigorous weeds were still deeply rooted in the garden bed.  I almost cried thinking about how much work and time it was going to take to get the weeds and grass under control.  Maintenance was going to be a problem.

I don’t have the time to pull that much stuff out of the garden on a regular basis, so it was time for plan B.  How could I get rid of the weeds without tilling or poison, without damaging the plants that I WANT to grow?  Then I remembered mulching with cardboard.  I have never done it before, but I know it works well.

The concept is simple, and there is more than one way to use it, but I am going to share how we are using cardboard in a garden that has already been mulched and planted.

Step one: Have a garden that has been planted, mulched, and is being overtaken by weeds.

Very weedy patch.

Step two: Gather cardboard.  Corrugated is best, and you probably want to get some that is brown and has as little ink on it as possible, but beggers can’t be choosers, so work with what you can get your hands on.

Cardboard prior to removing tape and labels.  I sent an email to local family and friends asking  for cardboard.  There are some huge pieces in that stack and it barely touched a fifth (maybe) of the garden.

Step three:  Open cardboard up to one flat sheet, remove all tape, staples and as many packing stickers as you can, you really don’t want the other stuff in the garden.

Step four: Pick a section of the garden to start with, large enough to fit said sheet(s) of cardboard.  You are working in manageable sections, don’t do the entire garden all at once unless you have a tiny garden bed.  Pull as many weeds from this section as you can, leaving any plants in the ground that you want to leave there.  If you need to move plants (i.e. volunteers), now is the time to do so.

Step five: Rake back as much of your mulch as possible in this section, being cautious not to damage any of the plants that you actually planted.  You want to either clear a section large enough to fit the sheet of cardboard, or you want cut your cardboard to fit the section you raked.  For the most part, I have been doing the former because we have a large garden.

Same section after raking.  You can see a mound of mulch to the left.

Step six: Lay down said cardboard into cleared area.   If you want to, you can wet the cardboard to 1) keep it from blowing away or 2) help it decompse faster.  I have not been wetting the cardboard because I do this on calm days, and the hay helps to weight it down, plus it keeps the cardboard slightly moist anyway, which brings me to…

Slightly overlapped cardboard.  I tucked the lower sheet underneath another sheet of cardboard that I put in a couple of weeks ago, and put the upper sheet on top of the lower one by a few inches.

Step seven: Rake the mulch back over the cardboard.

Step eight: Repeat steps three through seven until you cover all of the garden areas you want to.

Be sure to try and overlap sheets of cardboard, because this will help prevent weeds and grass from creeping in between small cracks.  I did actually overlap the two pieces shown, but it is hard to tell in this picture.  I have a few small cracks where this is hapening in the sections that I covered, but the weeds come out easliy, and there are so few of them, that it only takes a few minutes to pull the weeds that creep in.  You could always slip in a few more small sheets here and there to cover those gaps, which I will probably do once I finish getting the bulk of the garden completed.

As I said before, there are multiple ways to use cardboard for mulching or killing sections of grass to start a garden.  This is just the way I did it.  I should also mention that it is important that you weight your cardboard down with something.  If you don’t, your cardboard will probably try to make an escape on a windy or breezy day.  You could just use cardboard as a weed blocker, but if you do, you will probably have to use rocks or something to keep it in place.  (I have read about people using gallon jugs filled with water as weights.  It doesn’t really matter what you choose so long as it won’t poison your plants!)

This is the first section that I mulched with cardboard.  It was quickly being taken over by a nasty weed with a terrible root system.  I haven’t had any issues in this section since.

In the picture above, you can see three things that stand out, at least to me.  One, I let the cardboard hang over past the boarder of the garden.  The purpose for this is to destroy the surrounding grass, helping to keep it out of the garden bed.  I want to get a fence around the whole bed, and I want to be able to cut right up to the fence, and this will help. The second thing is the staked cucumber plants and row of peas, surrounded by clean hay, except for a little patch of weeds between the peas and the red stake…that’s where there was a gap in the cardboard.  Those are the only weeds that grew in that section in two weeks+ time (plus some growing in between the pea plants), I haven’t weeded that part at all since putting in cardboard. The third is that it is very clear where I started and stopped laying down cardboard…the abundance of plants (especially weeds) in the other areas really makes the clean hay pop out.

I have some large spaces in between plants because of the large amount of weeds that were growing in that area at the time of planting, and also I knew some plants will start to take up significantly more space by next month so I wanted to give room.  I will probably plant fall crops in some of these more open spaces in the next month or so.

So there you have it.  It’s simple and pretty easy, though I’d recommend doing this BEFORE you lay down your mulch.  But if like me, that wasn’t an option this time around, hopefully you can go back in and put some cardboard in and help save your knees and back from a lot of extra work in the long run!  The cardboard will eventually decompose, so by next gardening season (especially in a state where you get a lot of rain or a full winter) the cardboard will probably have turned back into dirt, but leave you free of a  lot of weeds and grass.  I hope this helps you as much as it is helping me out!  I think next year our garden will do really, really well because of this one simple step.


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