Raised Bed: What to put at the bottom?

sooby77April 11, 2010

Hi everyone,

I'm a novice gardener and am working on a raised bed this year (4'x8'x12"). I've been reading a lot on this forum and on the Internet and am getting information overload. My question is, what do I put at the very bottom of my bed? My plan at the moment is to dig up the grass (mostly weed!) and turn them over before putting something down. Some people recommend landscape fabric, some newspaper, and some cardboard.

I've started collecting cardboards from Costco here and wasn't sure if I am doing the right thing. My primary goal is to minimize weed. I know it's not possible to have weed free bed. Would it be overkill to lay a landscape fabric before putting down cardboard?

In my previous year, I planted tomatoes, semi successfully on the ground here, but it was a major pain to weed when mosquitoes are in full force. I plan to plant tomatoes, peppers, and herbs on this raised bed. Thanks for your advice.

PS: I'm in Raleigh, NC.

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Sooby, I'm in the cardboard camp (you know the one under the bridge by the railroad tracks). Seriously, I put cardboard or newspaper at the bottoms of all my raised beds and CPs. Weed minimization was the initial goal, but as I learned more about composting I realized it was good for the worms too. I don't know much, but I know worms are good for gardens. There's my two cents. Good Luck.

    Bookmark   April 12, 2010 at 12:10AM
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If you put the newspaper (or cardboard) on the top of your bed, instead of the bottom, you can have a weed-free garden, and you will have the added benefit, that mulches provide, of retaining moisture in your soil.

    Bookmark   April 12, 2010 at 7:11AM
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anpat, are you saying put cardboard around the plants in my raised bed? randy_coyote, thanks for your input.

    Bookmark   April 12, 2010 at 11:00AM
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mustard_seeds(4 -Onalaska Wisconsin)

I would skip the fabric and use a thick sheet of cardboard piled with several layers of organic matter. I was able to get extra thick cardboard from grocery when they would discard the large bins that are used to ship and store citrus and potato (about 1.2-1.5 cm thick stuff I recall). Gave grocery my phone number and they would call when they had an empty one for me. The beds originally held various veggies and plants that could go above the cardboard. Now 2 years later I can dig through the softened old cardboard and plant shrubs and trees into the native soil. The worms are amazing and I feel sad that my spade goes through so many of the little guys. No sign of grass under the old cardboard. I used several sheets of newspaper under the "seams" where one cardboard met up with another.

Good luck - it sounds like you are on the right path!!!

    Bookmark   April 12, 2010 at 11:05AM
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mustard_seeds - thanks for the input. The cardboards I got from Costco are thick ones. They were used to ship strawberries in. I'll going to pile them up like you suggested. Probably lay some newspaper too.

I was going to try the lasagna method gardening, but it would have to be set up this past fall. So that's too late.

    Bookmark   April 12, 2010 at 11:28AM
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Don't dig up the grass ... make the bed, put a couple layers of cardboard in the bottom, fill the bed and top it with a nice layer of newspaper under mulch. Plant by making holes in the newspaper for your seedlings.

No grass coming up from the bottom, and few weeds at the top.

    Bookmark   April 12, 2010 at 12:07PM
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lazygardens - that's a great idea. Basically poke holes on the top layer to plant the seedlings. You can't see the newspaper since it's topped/hidden by mulch. In this particular scenario, where should I put my soaker hose then? Above the newspaper or under?

    Bookmark   April 12, 2010 at 1:05PM
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gardenlen(s/e qld aust)

no need to dig at all cut what is there down low and cover with a good cover of overlapped newspaper, see our bale garden presentation for ideas.


Here is a link that might be useful: lens straw bale garden

    Bookmark   April 12, 2010 at 1:36PM
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toxcrusadr Clay Soil(Zone 6a - MO)

I always put a layer of soggy bread on the bottom and top, kind of like a dirt sammich.

Kidding! :-]

    Bookmark   April 12, 2010 at 2:15PM
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I to am planning on using cardboard in the bottom of my raised bed ---and have you thought of picking up a few mosquitoe plants ---my local school gave me one when i bought several other items from their plant sale fund raiser---they were all from cuttings the students did in the greenhouse ---smells like citronella---planted in a planter out back where i usually get skeeters and no-seeums ---wish me luck ---JB

    Bookmark   April 12, 2010 at 4:33PM
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What type of plant is this 'mosquito plant?"

    Bookmark   April 12, 2010 at 4:44PM
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pippimac(New Zealand)

Go the cardboard and paper route!
I'll say what everyone is tactfully avoiding. Please, please don't use landscaping fabric.
If you've got hardcore perennial grasses, you may have to take some serious action to kill them before you put your beds in, but with landscaping fabric you just end up with weeds coming through hideous plastic stuff that eventually falls apart in your garden. Landscaping fabric is awful. Does anyone find it useful or shall I continue my hate campaign unchecked?

    Bookmark   April 12, 2010 at 5:20PM
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I wanted to go the most organic route and wasn't sure about the landscape fabric. I thought they would disintegrate at some point in the future. But I think I'm just going to lay lots of cardboard and newspaper now.

    Bookmark   April 12, 2010 at 7:59PM
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Annpat, et. al., is right, cardboard makes a great mulch, but I use straw. It's looks better than cardboard and newspaper and I think it's easier to use, just grab a handful or flake and drop where needed. No watering to weigh it down, no shredding, no breaking down, no blowing in the wind (if straw does blow away, no complaining from the neighbors about cardboard and paper in their yards).

    Bookmark   April 12, 2010 at 11:32PM
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If your raised bed will be more than 6 inches in height there should be no reason to put anything on the present soil since what ever is put over what ever is growing there now at that depth will be deprived of access to sunlight and will die. The only reason you need newspaper, cardboard, or maybe landscape fabric when mulching is so you can use less material to accomplish the same objective, stop "weed" growth.
12 inches of soil piled on top of the grass growing there now will kill that grass with nothing else needed. Putting down landscape fabric over, or under, newspaper or cardboard is a waste of money, time, and energy since it will not do anything more than the newspaper or cardboard would.
It is possible to have a "weed" free planting bed by properly mulching the surface of that planting bed. A good mulch (something thicker than the 1 or 2 inches I usually see) will 1) aid in controlling unwanted plant growth ("weeds"), 2) will aid in soil moisture retention, 3) will aid in controlling soil temperatures, and 4) will add organic matter to your soil.

1 Like    Bookmark   April 13, 2010 at 8:14AM
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blameitontherain(8 PNW wetandwetta)

I'd like to join Pippimac's hate campaign against that tightly woven plastic fabric from hell ("FFH").

A few summers ago, I fell in love with a sweet little 1940's farmhouse which had beautiful gardens, professionally designed and lovingly planted. The landscape architect firm convinced the previous owner to go organic (huh?) by layering plastic FFH on all garden beds. This hideous crime against nature was then covered up by a layer of mulch.

Having no idea what lurked below, I happily skipped outside on a clear, crisp fall day, ready for the initial planting effort in my "new" home: Approximately 11,000 spring bulbs -- daffs, crocus, tulips and chionodoxa. La, la, la, here I go a-planting with my trusty trowel and buckets of bulb food. Ack! I had to rip, snip, fold, spindle (I know you can't do it to mail, but just how does one spindle, anyway?) and mutilate my way through the stupid FFH for every single da*n one of those bulbs. AND continue to have to do so every time I go to plant anything. I can't just rip the stuff out as most of the perennials will get ripped up with it.

Planting aside, the weed resistance factor quickly lost efficacy once weed seeds blew into the mulch. Weeds weave their way through the FFH and it is extremely difficult to get rid of them as their nasty roots get all entwined with the stuff in an unpleasantly enthusiastic pas de deux.

Cardboard and newspaper work great, top and bottom, with a layer of mulch on top.

Good luck with your bed, Sooby77. I was in your corner of the world on business last year and it is truly beautiful country.


    Bookmark   April 13, 2010 at 12:59PM
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Sooby--- I googled mosquito plant citronela and got a world of info ---another forum popped up on " Daves Garden "-----------

Very useful and insightful posts ---much like this forum

I'm gonna have fun with my mosquito plant and cuttings ----guy who gave it to me said it was "ugly" but the Dave forum sez it will bloom and other good things about it ---2 different kinds however ----citronella and lemon scented --read on and enjoy ----JE

    Bookmark   April 13, 2010 at 3:27PM
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I'm glad to hear everyone else here has such wimpy weeds that they are killed by a layer of cardboard and some mulch. The weeds here in west Texas can grow through asphalt shingles, pine 2x4's, plastic-coated nylon-reinforced tarps, cinderblocks, and concrete sidewalks. I had a weed grow up behind the brick on the exterior of my house and emerge from a light switch by the front door.

When I built raised beds I used a sodcutter to strip off the top 4-5 inches of grass and weeds. Then I waited a month for anything else to pop up. Then I used round-up to kill it. Then I built the raised beds. The problem was that down at about 18" below the surface were the root balls of the the spiny thistles and the orange roots of the beau d-arc trees. They came up through the soil, through the weed-stop fabric, through the 15" of soil, the newspaper mulch and the bark mulch.

Don't even get me started on how much the fire ants love to take up residence in a cozy raised bed...

2 Likes    Bookmark   April 13, 2010 at 4:02PM
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This is what I meant, sooby: People make raised beds and lasagna beds and start by putting cardboard or newspaper on the bottom. Then they pile 12 inches, or more, of fertile, weed-friendly soil, or fertile, weed-inviting organic matter, on top of the newspaper. Most weeds are not going to make it through the 12 inches of stuff that is put on top of the newspaper, so what's the point of the newspaper? Weeds will grow in the soil that the raised bed is filled with, so why not put your weed barrier on the top where it actually accomplishes something---keeping the weed or sod from reaching light.

If you really want a weed-free garden, put your mulches on the top of your soil, not under it. Or am I missing something?

I only find cardboard fit for paths or perrennial beds, I dislike it in vegetable or annual beds. It slips around, and it's much more difficult to apply than newspaper if you're putting it around small plants. I'm a newspaper girl, but, of course, I always cover it with something for pretty and for weight.

I feel like this is difficult to read. I'm sorry, I can't seem to do any better.

    Bookmark   April 13, 2010 at 4:22PM
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Gosh, thanks for all the great input. That fireant comment really got me worried now. I hope no fireant colony decides to make it their home in my new raised bed. I've pretty much decided on cardboard at the bottom of my bed. Went to Costco and collected more cardboard boxes today. I guess everything you do has an unintended consequences. I'll take the challenge as it comes. That's what this great forum is for!

I understand that if I cover the bed over winter, it'll kill the weeds. But what if I want to plant over winter. Is it even possible to plant anything over winter/year-round? Any winter vegetables? (novice gardener here!)

@joebob - thanks for the tip. I will check out that link.

@blaiminontherain - sorry about your experience. I can see how frustrating it is. The previous tenant of the house put up a giant sheet of plastic weed block on our backyard and it's starting to show up. And it's virtually impossible to rip them up now that weed and grass are growing ON TOP of it. Yeah, that's exhibit A right there not to use weed block.

    Bookmark   April 13, 2010 at 6:33PM
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Hi all,

I started this thread last year and this year I'm a little behind. I just tilled my raised bed and am trying to figure out the best way to prevent weed this year. I'm thinking of going the newspaper route.

I plan to lay a layer of newspaper on top before putting a light layer of mulch. I don't have a pickup and buying them by bags is very expensive. My question is, is it still possible to do liquid feed even though there's a layer of newspaper on top? Will the fertilizer just pool on the newspaper and evaporate away?

Incidentally, I was tilling the bed yesterday and lo and behold, there's a colony of fire ants on one corner of my raised bed. I'm pouring boiling water on them and see if I can kill them.

    Bookmark   May 10, 2011 at 1:11PM
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Natalia Mendez

Plans for starting raised bed gardens are under way, so all of these questions, answers and experiences are helpful. Anybody else on the topic of ants? I Know they like this area so it seems like I need to be on the lookout.

On that, "this area" is Tampa, FL. Research is definitely part of the process, but some tips on a personal level would be nice. Vegetables are the main prospected crop.

    Bookmark   February 19, 2015 at 11:21PM
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Boiling water will not do much to control Ants of any kind. The nest is so deep that by the time the water reaches it the water has cooled off and does no harm. Don't waste your time and energy on this myth.

The purpose of newspaper, or cardboard, in mulches is to provide a means of blocking unwanted plant growth (weeds) access to the sunlight they need to grow. Newspaper, and cardboard, allow a grower to use less of the other material then would be needed without that medium. Initially, the paper put down as mulch can keep liquid fertilizers from getting into the soil (pour some water on a sheet, or 4, of paper and see what happens) although as the paper is digested that fertilizer will be moved into the soil. If covered with something any fertilizer on the paper will not evaporate, although it is best to get the nutrients into the soil before applying a mulch.

Texas A & M has done more research on control of Fire Ants than anyone else and most others with information about them uses what TAMU has published.


kimmq is kimmsr

    Bookmark   February 20, 2015 at 3:39AM
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toxcrusadr Clay Soil(Zone 6a - MO)

Natalia, you might use the search engine to search this forum or all of GardenWeb for 'ants'. We've had other discussions on them. I can't say whether the boiling water works well or not, as I haven't had ant problems. It will certainly kill whatever it hits before it cools off, but I can see a deep colony not being totally wiped out. It could be a nice non-toxic cheap component of a multi-pronged attack.

    Bookmark   February 20, 2015 at 7:46AM
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missymoo23_(z9a_Tx)(z9a Tx)

Somebody said to use sugar to kill fire ants....I think their child had done a science project. I've done it twice this winter and it really worked. I used a whole bag of sugar each time...YMMV

    Bookmark   March 3, 2015 at 9:38AM
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