How to Build Table-Height Raised Garden Beds

Recently I’ve been asked by a handful of people how to build the table-height, handicap accessible garden beds we installed at Selah Community Garden last year. I figured the easiest way to make our plans accessible to the most people was with a blog post. Of course, I’ve never written out a woodworking guide, so this might read more like a recipe…

 

Before I describe the plans, I must give a huge thanks to two very important church members, Sam Robinson and Jerry Paulus. Sam and I collaborated on the initial design of these beds and together built (and learned from) the prototype. Jerry came behind us and improved the beds with some much-needed bracing. Nothing would have happened without the work of these two great men.

 

So, here’s the plan; for each table-height bed you will need:

 

  • Two 8’ long 4”x4”
  • Three 12’ long 2”x10”
  • Five 12’ long 2”x4”
  • 35 sq. ft. ¼” hardware cloth
  • Several 4” wood structural screws
  • At least twelve 6” wood structural screws

Construct the garden box using the 2”x10”s, a rectangle 4’x8’ (short boards on the “outside”). Use one 8’ long 2”x4” to brace across the bottom, lengthwise. Laterally brace the bottom of the garden box with nine 4’ long 2”x4”; this will be the support for the hardware cloth and the soil. See image below.

Garden Bed Plan

The rectangular garden box is then raised up and supported on 4”x4” posts; one at each corner and two along the middle of the long sides. I recommend setting these at a height that best suits you; the top of our first bed was at 40”, which we found to be too tall. The rest we intentionally lowered to 32”. Keep in mind that the top of the bed will be the bottom of your plants, so plan according. We used 26” long posts and notched them to fit the 2”x10” boards.

I strongly suggest notching the top of the 4″x4″ posts six inches, so that the 2″x10″s sit on the wood and are supported by more than just screws. Keep in mind, there’s going to be a lot of weight once this thing is loaded down.

 

With your remaining 2”x4”s, brace the legs at 8” above the bottom. We did one 8’ long 2”x4” along each long side, and a 4’ long 2”x4” between each pair of legs along the short side (three total). We ran the bracing along the inside of the legs, so the measurements are actually a couple inches shorter.

 

There are two triangular braces at the top of each leg. These are cut from the last 2”x10”; the easiest way to do this is to cut six 10” squares from the final 2”x10” board, then cut each square into equal right triangles. Using the 6” wood structural screws, attach each triangular brace against a leg and the body of the garden box.

 

Your table-height bed should now be fully assembled. Lay your sheet of hardware cloth across the top then push it down into the box. Using a hammer, go around the inner edges and gently tap the hardware cloth as flush as possible into the bottom of the box. Line the bottom with newspaper (optional) then fill with soil. Voila! You are ready to plant.

Important Notes

 

We used rough cut, untreated lumber that we “finished” by scorching with a blowtorch. That means that our boards were true to measure; if you are not using rough cut lumber, you will either need more wood or you’ll need to reduce all measurements by ¼”.

 

For all joints other than the triangular braces we used 4” wood structural screws, at least two per joint (sometimes three). The triangular braces must use 6” wood structural screws to give it the best support.

 

The hardware cloth along the bottom provides excellent drainage without loss of soil; however, these beds do not hold moisture as well raised beds that are on the ground. As a result, they must be watered more frequently.

 

All measurements on these beds can be adjusted to best fit your context. However, garden vegetables need a minimum of six inches for root depth. While all measurements are adjustable, I would not recommend making your garden box any shallower than 10” to give your veggies enough room.

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