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buggalinajujubee

Raised bed over concrete, what for a bottom?

BuggalinaJuJuBee
13 years ago

If you want to put a raised bed over a concrete path, do you need to have a wooden bottom or can you staple that landscaper cloth inside to the bottom of the box to hold in the soil better?

My husband made me square boxes with a wood bottom and drainage holes drilled in. It worked fine last year. This year I am considering purchasing some raised beds but there is no bottom. I go for a minimum of 12 inches deep with all my boxes.

Thanks,

Julie

Comments (13)

  • sinfonian
    13 years ago

    Well, my problem with a wood bottom is that eventually it will rot out. Plus, unless you have drainage holes it'll become a bath tub. For concrete, I like the idea of stapled landscape cloth at the bottom to keep as much of the soil from escaping. I think a that would likely solve your drainage issues as well. Just my thoughs as I have gravel under mine, then dirt. GL!

    Here is a link that might be useful: Sinfonian's garden adventure

  • bsntech
    13 years ago

    I have raised beds sitting on my driveway.

    In all honesty, I didn't put anything underneath. I just made the four sides and filled with dirt.

    It is going to look very bad if I get rid of the beds (or we move to another house). I'm sure the concrete will be stained.

    Here is a link that might be useful: My Garden Blog

  • lgteacher
    13 years ago

    I put boxes over asphalt to make a school garden. The bottom was lined with landscape fabric to prevent the soil from washing out. They've been in place for about a year now and everything is working out well, except for the aphids.

  • Keyboarg
    10 years ago

    Would also like good ideas for raised bed on my terrace

  • adiasc
    8 years ago

    This is great to hear, I am in the process of building a few planters to section off part of a cement patio and I was thinking of leaving them without a bottom, but putting a couple inches of gravel as the first layer for drainedge, sound good? Also they are 18" deep, does anyone know if perenials, such as reed grass, or small emerald cerdars, would over winter in raised beds? It gets to -30 where we are. I am looking to create privacy with them. Thanks

  • lgteacher
    8 years ago

    Gravel at the bottom will not help drainage, but will create a perched water table. The layer of potting mix or soil will be damp right above the gravel. You can read more about a perched water table in the soil section of this forum.

  • adiasc
    8 years ago

    Thank you for responding, I can't find the thread about this. Without a bottom won't the water just drain down throught the gravel and then seep out the bottom onto the driveway? Appreciate the help


  • adiasc
    8 years ago

    That's excaclty what I am hoping, the gravel beneath the soil will allow the excess water to drain out once the roots have soaked up what they need. So this "perched water table" is not really a concern aftert all? Thank you


  • lgteacher
    8 years ago

    Here is the link. The potting mix right above the gravel will hold onto water. Skip the gravel.

    gravel in containers

  • adiasc
    8 years ago

    Wow! That was intense and I can't say it really left me feeling more clear on anything, I am not using potting mix, but acording to that forum I gather one uniform soil is better than layers of varying textures....? It is hard to picture the plants not drowning in 18" of soil right on the concret, but I suppose I'll trust the experts and give it a go. Thanks


  • lgteacher
    8 years ago

    A uniform mix or soil will work better. Most of the vegetable roots will be in the top six inches, but some can go a lot deeper.

  • adiasc
    8 years ago

    Thanks for all you help, these planters are for perenials that I hope will over winter ok. As I said in my original post it gets to be -30 even -40 here (zone 4)and I am hoping iether Karl Forester reed grass or dwarf emerald cedars will make it.

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