Recipes and techniques for raised bed gardening soil

Discussion in 'Soils, Fertilizers and Composting' started by SunnyDay, May 5, 2008.

  1. SunnyDay

    SunnyDay Member

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    (Merville area) Comox Valley, Canada
    The soil I have under my lawn/sod is dry, sandy and very compact. It's an old unkempt lawn that never gets watered in summer. The grass is very tightly grown and rough.

    I've just built six veggie boxes out of untreated spruce. Each box measures 10' long x 3' wide and is 10" in height. It's been months of trying to decide whether to take up the old grass first or just to cover it with cardboard/newspaper and add the topsoil/compost mixture right on top. I've been asking around for about a year. For either raised veggie boxes or flower/shrub beds, here are the different things I've been told:

    For Right Now:

    *Shovel up the sod, get rid of it (or compost it), add 1’ of topsoil/compost, plant

    *Shovel up the sod, get rid of it (or compost it), lightly rototill the ground, add 1’ of topsoil/compost, plant

    *Shovel up the sod, get rid of it (or compost it), cover it with landscaping fabric (the black stuff), then add 1’ of topsoil/compost mix, plant

    *Cover the existing lawn/sod/weeds with 1-2 layers of clean cardboard OR 5-7 layers of black ink only newsprint OR 5-7 layers of clean newsprint. Add 1’ of topsoil/compost. Plant.

    *Cover the existing lawn/sod/weeds with 1-2 layers of clean cardboard, wet it, add a 1" layer of straw, 1" of fish compost, then your 1’ of topsoil mix. Poke a hole through the cardboard for each seedling you are planting, so that their roots can get through.

    *For shrubs and trees in beds: Cover the existing lawn (that you want to kill) with lumber yard plastic or tarp (it's a heavy plastic, white on one side, black on the other). Score a large X in each place where you plan to put your shrub or tree. Cover with 1’ of topsoil. Plant.

    If You Can Wait a Year:

    *Shovel up the sod, turn it over (grass side down), cover it with 5-7 layers (sheets) of black ink only newspaper, wet it thoroughly, cover that with a layer of clean cardboard, weigh it down with rocks, wait one year, remove only the rocks, then add 1' of topsoil onto all of it and plant it.

    *Cover the existing lawn with 1-2 layers of clean cardboard OR ½” layer of black ink only newsprint OR ½” layer of clean newsprint. Weigh it down. wait one year. Uncover and rake out dead grass. Add 1’ of topsoil/compost. Plant.

    *Cover the existing lawn with lumber yard plastic or tarp (it's a heavy plastic, white on one side, black on the other) - black side up. This attracts more heat. Weigh it down. wait one year, uncover it, rake out the dead grass & rocks, add your new topsoil/compost mix. Plant.

    So there’s what I have found out. They all sound like they take a lot of work, no matter which one I choose. I cannot say I agree some of them; some methods are apparently for keeping weeds or grass down, for killing the grass, for retaining soil – who knows. Oh, and the amount of topsoil to put on top ranged from 6" to 16", I just wrote 1' for averages sake.

    As for the ingredients in the topsoil, most people said anywhere from 75% topsoil/25% compost to 50/50. And it was anything from topsoil and composted manure to topsoil and fish compost. Out here we have places that well fish, mushroom, manure composted to expensive blends called SeaSoil, Black Gold. I only have a small round black compost bin, so not enough to fill the boxes I have. I have to buy topsoil/compost and have it trucked in as close to the garden as possible.

    Does anyone have any comparison of these different methods? Any thoughts?
  2. Daniel Mosquin

    Daniel Mosquin Paragon of Plants UBC Botanical Garden Forums Administrator Forums Moderator 10 Years

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    Vancouver, British Columbia, Canada
    By told, I guess you mean that you have asked around.

    Others will be able to add more specific advice, but for now, I can say with some certainty that you don't want to create a barrier to the roots by putting down landscaping fabric, newspaper, etc, particularly so if you plan on having a shallow bed.

    Helpful advice can be found from a number of the US Cooperative Extension units by searching for site:edu soil for raised garden beds
  3. mcoveny

    mcoveny Member

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    Langley, BC
    I created a 14' extension to an existing fountation planting. the soil type was sandy to start with. in the fall, I covered the area (14' x 8') with wet newspapers, then I raked the leaves from trees on the property and placed them on top. Fortunately, it rained with a minimum of wind so the leaves stayed put until I was able to get a load of topsoil to place on top. It raised the area approx 8". but in the spring, it was wonderful to plant shrubs, flowering perennials and have everything grow so well with very little evidence of what was underneath (grass and leaves). I didn't turn over the grass beforehand and I hadn't shredded the leaves before placing them. Since that time, I have shredded the leaves, spread them on the vegetable garden and turned over the sod in the fall as preparation for the winter. In the spring, one pass with the rototiller and it was ready for new planting--just remember not to plant the same crops in the same location in the garden (good old-fashioned crop rotation)
  4. Debby

    Debby Active Member 10 Years

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    Vancouver, Canada
    You might do just as well with clean fill, stuff from a nearby building site. To it you could add peat moss, SeaSoil, and perlite. Would be expensive, but weed free--unlike some topsoil that has who knows what in it. Too many examples of imported horsetail and morning glory around my neighbourhood for me to trust any topsoil source... And a newspaper barrier would be fine for crops other than parsnips and carrots I should think.

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