An Improved Raised Bed Garden

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Introduction: An Improved Raised Bed Garden

About: Retired, doing art work now. Great. Have the time and the money to spend doing what I want to do.

I have been using raised beds for several years now. I converted an existing patch of grass into four, 4ft x 12ft raised beds for a total garden area of 192 sq. ft. This could, conceivably, produce enough food throughout the year to make a serious dent in the food budget. And, of course, all the advantages of raised-bed gardening are realized. However, I have had to replace several end boards due to rotting out at the corners. In order to prevent this from happening, I came up with a way to use concrete as a corner brace, and thereby stop the rotting and make a more permanent installation. Starting in step 7, I show how to replace an end board that has rotted out at the corners.

Step 1: Materials Needed

The usual concrete tools, materials and supplies. For my mix, I used a ready mix concrete so that I would be sure to have a uniform, strong concrete. For the bed itself, I choose to use 2x dimensional lumber. At least one bed is made with 2x12's, one with 2x10s, and so on. A 2x6 is certainly big enough, so it is a matter of personal preference. In this instructable, the lumber is 2x8's.

Step 2: Making the Form

The form is made using 1/4in. plywood, and 1x6 lumber cut to the correct sizes. See pictures for specifics. A key part of making these braces is the addition of a piece of wire mesh into the mold. I chose to use some rabbit wire for my reinforcement. It is easily cut with wire cutters, and shaped to fit within the mold between the bolt holders....these have been made out of regular PVC pipe, which is the 1//2 inch size. The form is assembled using drywall screws. Before assembly, it is a good idea to apply a coat of oil to the wood pieces to act as a release agent for the concrete. I just used some vegetable oils, but any oil will do.

Step 3: Mix and Pour Concrete Into Form

Plan on letting the form set for 24-48 hrs to insure maximum strength. Concrete goes on curing for several more days if not weeks, but 48 hrs is sufficient for the first set.

Step 4: Remove Brace From Form

I unscrew the outside piece of the form which moves away easily after the bolts have been removed. By gently tapping on the wood part of the form, the concrete easily separates. So what we have is a corner brace of reinforced concrete, "predrilled", ready to accept your end or side pieces, and should last a very long time. Will simplify any future replacements should they be necessary.

Step 5: Assemble the Bed.

To assemble the bed, I use 5/16in. Bolts of the appropriate length. For this particular bed, 4 or 4 and 1/2 in. bolts are used. One washer is used on each end of the bolts. For this example, the bed is 4ft on each side. Any size can be made, but my original beds are 4ft x 12ft. Make them the size that fits your space.

Step 6: Fill Bed With Garden Soil of Your Choice

In order to supply your plants with the absolute best growing conditions, you want to use a high quality garden soil. I have a compost bin, and also purchase commercial organic compost as needed to resupply the beds. Many books and methods are available for enhancing the gardening experience, and the viewer is referred to them for help in maximizing food production with this method of gardening.

Step 7: Replacing a Rotted End Piece

I have replaced several of these pieces, but they continuted to rot out. Hence the corner brace of concrete. Replacing the piece is simply a matter of unbolting the old piece, cleaning up the area so that the new pieces can be put into place, and installing the new corner braces.

Step 8: The Finished Repair Job.

With this new corner brace, I expect the end boards will last considerably longer than just bolted wood. Time will tell.

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103 Comments

i was given some 2x10s x10ft. I want to make raised beds, unfortunately some of the boards are split,if I brace them, would i brace them vertically across the split, or horizontally? I really would appreciate help on this. Love all your projects, very inspiring.

1 reply

Thanks for your comments, RuthS1. I think I would brace them across the split, if necessary...you didn't indicate HOW split they were. If it's minor, no bracing would be needed. I always coat the wood that will be inside with an asphalt coating(as in roofing asphalt). Then I use black plastic to line the boards with so that there is no leakage of the asphalt materials into the garden soil. If you can do that, you will get 15 to 20 years usage out of those 2x10's! Hope this helps.

What a great idea. Hope I can do that.

Nice pavers! I used the same pavers / form for my entire home!
https://www.facebook.com/media/set/?set=a.522403854473323.1073741837.508872869159755&type=1&l=8a292ab03c

3 replies

That is one awesome, serious project! 5 stars for sure, you should enter it in all the contests you can find...a sure winner. Thanks for sharing, and did you do an instructable?

I love how you used the pavers between the raised beds; gives me some ideas - i was kind of in the market to build a veg garden and want it to look nice; yours is awesome!

thanks man! negative, i did not make it into an instructable! maybe one day i will :)

I love your set up and the walkways in between and around the beds. I have to ask (because I believe this is the design I have planned for my garden)..but are the walkways made by using the Quikrete walkway mold? I had a vision and love seeing what it would look like once finished. Awesome job!

2 replies

Thanks for your comments muffycase! Yes, I used the quckcrete mold...they are alot cheaper now than when I bought it...

That's the same one I used:
https://www.facebook.com/media/set/?set=a.522403854473323.1073741837.508872869159755&type=1&l=8a292ab03c

I really enjoy the open discussion and trading of ideas this instructable has spurred. The concrete corners are an excellent idea, but i wonder if it would also be possible to form reinforced concrete walls as well, using rebar or mesh. The walls themselves would use a different mold, but once you build it you are unlimited as to the number you can produce. Just a thought to bypass the issue of rotted wood and potential leaching of chemicals. Again, great instructable and I really like the discussion going on here.

we don't have rabbits, or gophers. we do have possums, skunks, and I have 2 cats. I am more worried about the cats thinking it is the best litter box ever.
I love your design. I am pretty sure Hubby will dig it. Since he is the "builder" he needs to like it. thanks,

1 reply

About your cats, if it gets to be a real problem, you may consider getting this device that emits a very hi-frequency sound (humans, not even birds can hear it), but only when the animal gets within range. The cat will come to associate the unpleasant noise with being in the garden or wherever he happens to be that he shouldn't be. Here's the link: http://www.safepetproducts.com/cat-stop-cat-repellent-1-cat-repellent-on-the-market.html?utm_source=msn&utm_medium=cpc&utm_term=contech%20catstop&utm_content=m350715038&utm_campaign=msn-campaign-catstop#.UZIrGKDn91s. You can also try planting Rue, Bergamont, Coleus Caninea (aka Scardy Cat plant), lavender, geranium, rosemary & garlic cloves, or plant prickly plants in and around your garden... all of these are known to deter a feline's interest in an area to a certain extent. And/or plant a cat garden with cat nip, grasses and let him know this is his place.

What is the cost overall for one 4X12 bed?
Is 4X12 a functional size?
Do you put any chicken wire across the bottom to limit gophers?
Can you add an upward post to the corners for a fencing around the garden? (to keep the dogs and cats out of the garden.)
Thank you so much. Sara

1 reply

Sara: I originally spent $200 for four beds. That could vary widely depending on materials chosen, and the extent you want to go to. This size was perfect for my spot, and the dimensions lend themselves very well to square foot gardening. I didn't line mine for the gophers, but it would have been a good idea. Yes, they can be fenced as you suggest...I haven't had to do that, although the racoons do considerable damage looking for grubs and such....good luck.

How come you didn't go with that green treated lumber or perhaps cedar? Cost?

4 replies

The green in treated lumber is either amine copper quat (ACQ) or copper azone (CA), both of which are poisons. Having them mix with ground soil and water may leech into the plants -- not a healthy idea. While expensive, hardwoods like redwoods last much longer. A note to Creativeman: Bolted ribs (stakes bolted to the sides of the planks) that are twice the size of the planks (half on the plank, other half buried) will relieve much of the stresses put on the corners and will increase the rigidity of the overall form.

 This isn't entirely true...

OLD CCA lumber has been banned for consumer use since 2003/2004 ... Arsenic was the main component there that was causing problems... Pressure treated wood now still has copper in it... but copper interacts with other metals in the ground not really plants... Some people even plant copper wiring to ward out snails and slugs as pests in their gardens!

I've used pressure treated wood in my raised vegetable boxes and its been great!

You realize of course you are probably going to die a slow an agonizing death now. All those harmful copper toxins you have been eating all these years are adding up and pretty soon BOOM!, your insides are going to explode!

Really, I think some people take this organic thing a bit far....

Copper wire is pure, metallic copper in solid form that will only leach in tiny, tiny amounts-NOT so in the pressure treated wood. The copper in PT wood had to be put into a very soluble form to permeate the structure of the wood and it's the SOLUBLE metals/toxins that you need to worry about.

Remember, most of your plumbing (other than the waste/discharge lines) are made of pure metallic copper and has been for generations and hasn't caused problems...yet...