Need Help On Constructing Raised Beds

cmpman1974

20 years ago

Hi everyone,

I read a recent post about using either 1 inch or 2 inch lumber to construct a raised bed. Great suggestions and advice. I currently have 5 raised beds. Two of them are 4' x 12' x 12" high. The other three were 4' x 12' x 8" high, but 4" of the bed was buried in the ground.

I have terrible native soil so I need to have 10-12" of high quality soil. I brought in good soil for my 1 ft high beds last year and tried to amend native soil in the others. The latter strategy just did not work and would take years to have viable soil. My tomatoes are 2 ft taller in the better soil beds ao I am more than convinced this is the route! I am re-doing my other beds.

If I wanted to build a 4' wide x 8' long raised bed with walls 18-20" high, what would you all suggest as the most stable way to build it without having the walls bow out much? Most of my beds are 12" high now, but I want to go deeper as an experiment and partly because I already have about 4" of crappy soil above ground. I plan on piling good soil on top of the clay-like stuff.

Any suggestions would be appreciated. My other beds are made with 2 by 12 untreated wood planks. Obviously to go 20", it would require putting double 2 by 10s or landscape timbers. I never figured out how to construct a bed using landscape timbers, but I sure would like to! It would probably run up in cost to get it that high though!

Brick is out of the question. Too expensive, though probably most durable and long lasting.

Chris

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Comments (3)

username_5
20 years ago
I have no experience building beds 18+ inches high.

Disclaimer aside if I were to attempt it my instinct would be to use cedar 6x6 and stack them 3 or 4 high. Each would be drilled every 4' or so wide enough that I could pound 1/2" steel rebar 2' into the ground below and have it flush with the top.

If I saw even the slightest movement of the 6x6 I would put rebar or other stakes on the outside of the bed.

Before actually constructing this though I would price out the difference between this and the no mortar retaining wall bricks.

Thing is I would never make a bed that high. It would be less costly to dig down into the bad soil and replace it with good soil and use 6-12" beds. Sure, the clay surrounding it would fill like a swimming pool in the rainy season, but not much has deep roots then. In summer it would be fine.
Jon1270
20 years ago
I share the skepticism about whether it's worth it to build such a high bed, but one easy way to prevent the long sides from bowing out would be to tie them to each other with a couple lengths of threaded steel rod towards the middle, with large fender washers and nuts on the outsides of the bed, to hold the sides in. You might want to counterbore the holes so the ends of the rods are recessed and you don't catch clothing on them.
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darkcloud
20 years ago
I currently have 5 raised beds. Two of them are 4' x 12' x 12" high. The other three were 4' x 12' x 8" high...
If I wanted to build a 4' wide x 8' long raised bed with walls 18-20" high, what would you all suggest as the most stable way to build it without having the walls bow out much?

Ok I'll bite. Did I miss something here? Are the old 12ft long beds bowing?

Landscape timbers would certainly NOT bow, tho I would not use them purely because of $$$. Dunno - make 2 4bys and put em together? Put a reinforcement on the side you think 'may' warp kinda like a shelf or an 'L' or turn the 'L' upsidedown to make a sitting place.

As already mentioned dig down, double dig or till the native soil 1st. Amend as neccessary then make it 6" high.

Maybe it's me but I think if YOU made 5 beds already 12ft. long YOU have some idea what you are doing. Is this some sort of test? Hire a contractor to warranty it!!