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New Gardener(Raised Beds)

I am building 2 raised beds for my mom who is handicapped. I have never done anything like this.

I was going to make them out of cinderblock(17' x 9') and was thinking around 36" high.

Two questions:

1. I want to put heavy landscaping fabric underneath each to seal the beds and was wondering if that was deep enough alone for the roots to grow(tomatoes, onions, peppers, zucchini) or if I should go higher even.

2.Drainage. I am building these two beds and then surrounding the area in brick pavers as a sort of outdoor patio. I was thinking before any of that to dig several wide-mouth PVC tubes under the raised beds and beneath the ground for water to drain and then off further down the yard. Or should I just drill holes in the bottom along sides of the cinder block? I didn't want a bunch of dirty water spilling out all the time was the only problem.

Thanks for any help. Zone 5

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I'm no authority on raised bed gardening, but I would suggest that you reconsider the 9' width. Your mom probably isn't going to be able to reach 4 1/2 feet to the center of the bed for purposes such as weeding, plant care, or even harvesting.

OTOH, perhaps I'm not envisioning the bed correctly. :)

Super Green Thumb
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These are my raised beds from last spring. They measure 4' X 8' with about 10" of soil in each.


From the following photo, I think you can see raised beds don't need to be made from cinder blocks, they don't need to be really large, and you don't need 36" of soil. My garden produced well all summer.



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Agree with all the above. Usually beds aren't made any wider than 4' (can be as long as you like). Part of the idea of the raised bed is you never walk in it, so you never compact the soil. But to not walk in it, you have to be able to reach everything from the edges.

You're making it more elaborate and complex than it needs to be. I don't understand the point of the landscape fabric and pipes and everything. If you just put your bed on top of the ground, any excess water will drain down into the soil.

If you need to make the beds 36" high for your handicapped mom to be able to reach it that's fine (and what a great project! you are a wonderful son!). But understand that that is huge and will take (literally!) a ton of dirt to fill. You probably will need to have a truckload of topsoil brought in.

If she doesn't need it that high, less is fine. I have 20" raised beds sitting on top of a concrete patio, so no dirt under them for plants to grow into. My tomatoes and everything do just fine there.

Tom the Elder
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Also keep in mind that the taller you make them, the more likely that water will seep out of the brick joints and stain the outside of the bed. If that is a problem, hang plastic sheeting down the sides to keep the water away from the bricks.

Also, at that height you are looking at more than a ton of soil. If the soil is three feet wide by thee feed deep, the volume for every 3 feet long = 27 cubic feet = 1 cubic yard. Assuming the soil is most, is is probably something like 80-100 pounds per cubic foot (lighter if there is lots of organic material). So you will have more than a ton of soil for every 3 feet of bed length.

Good luck. I hope you will return in the fall and describe how it worked out.

Super Green Thumb
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If she uses a wheelchair, I can report that a well-respected community garden in the East Bay has accessible raised beds which are approx. 20 inches high. The garden has been open since 1994 in a disabled-aware community, and there is a waiting list both for regular raised beds and for the 20-inch beds.

Maybe this is another possibility?

Cynthia H.
Sunset Zone 17, USDA Zone 9

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Also for wheelchair-use, I once saw a raised BENCH-bed somewhere -- using cinderblocks as supports for wire mesh surface often used for greenhouse "bench" or table, with deep boxes of potting soil on top. I'm guessing that one was 6" deep as per Mel Bartholomew's New Square Foot Gardening but I remember cynthia_h mentioning that 6" is insufficient and 8" or more would be better.

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