I would like to start a vegetable garden. The problem is I've planted so many fruit trees in the ground that there's no more room for vegetables. The only way I can start my vegetable garden is to place it over the concrete in my back yard. The natural choice for gardening on hard land would be elevated planters:

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But these elevated planters are just so darn small and darn expensive (~ $200). On the other hand, normal garden beds are usually much bigger and cheaper. I'm considering getting this behemoth:

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The problem with garden beds is that they don't have a bottom. What precautions, if any, should I take with the bottom if I were to put this garden bed over my concrete? Will drainage be poor? Will I need to cover the bottom with something? Do vegetable roots not like hitting into the concrete?

  • 1
    check the slope and drainage so the water has somewhere to go
    – kevinskio
    Commented Mar 12, 2014 at 10:02
  • 1
    Have you considered interplanting your fruit trees with vegetables? Not all veggies will tolerate this, of course, but your greens, herbs, pole beans can all grow under the trees. Sun loving veggies will also do fine on the outer edges of the tree's canopy. My mother-in-law lives in a desert climate, and plants all of her veggies under her trees to conserve water. She has some of the most beautiful basil and greens I have ever seen year after year.
    – michelle
    Commented Mar 12, 2014 at 14:12
  • My entire backyard slopes toward the front of my house (my house is on a slant). I can't plant the vegetables between my fruit trees, because those are situated near my south fence - short things wouldn't get any sunlight.
    – JoJo
    Commented Mar 12, 2014 at 16:32

1 Answer 1

  1. Yes drainage will be poor
  2. No plant likes its roots to be hitting concrete
  3. Whether you'll have any success rather depends on what vegetables you want to grow. Root crops won't cope at all with the arrangement you're proposing.

If you want to use something like the pictured arrangement, you'd need to put a bottom on it, with drainage holes, and stand the whole thing on some kind of support - it only needs to be an inch or so off the concrete beneath. This would enable proper drainage, but again, you're restricted as to what vegetables you can grow with such a small amount of root depth. If the arrangement had planting boxes 8-12 inches deep, that would make the whole thing do-able, provided you're not growing root crops.


Jojo, that presumably means the top tier extends right to the bottom of the structure, and isn't separate from the soil in the lower levels, which would enable you to grow tomatoes, as shown in the picture, certainly. You haven't said which veg you want to grow, of course, but I wouldn't try, for instance, potatoes in it. If you can get a bottom on it and raise it slightly, it's quite an attractive bit of kit, but it does depend on what you're thinking of growing as to how useful it will actually be.

  • The product description of that three tiered garden bed says that the topmost tier is suitable for plants that need deep roots
    – JoJo
    Commented Mar 12, 2014 at 22:52
  • In this video tutorial on how to make a raised garden bed, the guy lays landscape fabric below the bed. Does that mean roots won't be able to grow beyond the height of the bed?
    – JoJo
    Commented Apr 24, 2014 at 16:24
  • Yes. There are plants that penetrate through geo textile, but veggies won't be among them.
    – Bamboo
    Commented Apr 24, 2014 at 18:00

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