Thursday, May 17, 2012

Finishing My SFG – Adding the Final Beds, Part I

Last year I planted my tomatoes in a row at the end of my plot in the Bolton Community Garden since I had already built and filled 8 raised beds and planting season was well underway. The plan was to finish the implementation of raised beds this spring with the addition of two 4x6 raised beds. These beds were going to be used for tomatoes along the long side of the boxes, planted 1 per square and trained up a trellis.

I began looking at alternatives, buy versus build, cedar versus composite. I actually bought a couple of cedar raised beds from The Farmstead. They had a 4x6 box using 5/4 rough sawn white cedar lumber with mortise and tenon joints, 8 inches deep. These same beds are sold by other vendors, including White Flower Farm. The best price was from The Farmstead itself, $104.50 for a 4x6 including shipping. Unfortunately, the specification were a bit lacking. The quoted dimensions were for the total length of the side pieces, including the mortise and tenon. When you assemble the boxes, the interior dimensions are a bit more than 3x5 feet, or 15 squares, quite a bit less than the 24 squares I was planning on. I decided to keep the Farmstead beds and use them at home for strawberries and herbs. For the community garden, I decided to build my own beds.

The decision to build my own was based on the discovery that Lowes carried 1x8 cedar lumber (the Home Depot I checked only had 1x6 and I wanted a little more depth for the tomatoes, despite what Mel says). So the boxes were going to be constructed of 1x8 cedar (Lowes had 8 and 12 foot lengths, which was perfect). I also bought some 1x2 and 1x4 pieces to use as corner blocks and as braces for the bottoms. The beds are going to sit on blocks to keep them out of the standing water that we frequently get after a hard rain, so I would need a bottom. I planned to use hardware cloth rather than plywood for the bottoms, with landscape fabric to keep the mix in the boxes. Assembly in the garage was fairly easy, as shown below.

I had Lowes cut the 12 foot pieces in half, and I cut the 8 foot pieces in half for the ends of the boxes. I then laid the pieces out and used picture framing jigs to assemble and square the box.

Using jigs to square up the box

Next I drilled pilot holes and used three 1 1/4 inch galvanized deck screws to attach each end of the box. After doing that I could remove the framing jigs.

Screwing together the corners

The next step was to use 1x2 cedar strips cut into 7 1/4 pieces to reinforce each corner. I used more deck screws from outside to screw into each corner block. Then I measured and cut more strips of the 1x2 and attached them along the bottom of the box between the corner posts, using the deck screws from the inside. These strips will give me a surface that I can use to attach the bottom of the box. I should add a caution here about overdriving the screws. The cedar is very prone to splitting and if you overdrive you can easily split the wood. That is also why it is wise to drill pilot holes first.

Applying corner blocks and a bottom rail

Since I did not like the idea of using plywood for the bottom, the plan was to use half inch galvanized hardware cloth. To keep the Mel’s Mix in the box, the bottom had to be lined first with landscape fabric. I used a fairly heavy spun bond polyester cloth that hopefully will drain well. Since I could only find it in a 3 foot width and the box is slightly longer than 6 feet, I had to overlap multiple strips, first one in the middle and then two more on the ends. The fabric was stapled to the box using 1/4 inch staples.

Applying landscape fabric to bottom

Next I applied the hardware cloth, which again I could only find in a 3 foot width. I applied two strips, which left a small gap in the center which would be covered with a brace. I used 3/4 inch galvanized poultry net staples to fasten the hardware cloth to the frame.

Attaching half inch galvanized hardware cloth with U staples

Next step was to reinforce the bottom with some braces to help the hardware cloth support the weight of the Mel’s Mix. I used a 1x4 for the middle, using the extra width to cover the gap between the two pieces of hardware cloth. Then I added 1x2 strips on either side of the 1x4, halfway from the 1x4 to the end of the box. These were attached with deck screws.

Adding cross braces for support

The garden plot was prepped by weeding and raking the soil as smooth as possible and covering it with landscape fabric to deter weeds between the boxes.

Preparing the garden with landscape fabric

The boxes were transported to the garden one at a time on the top of my SUV. They are light weight and one person can easily carry them, but it does take two people to put them on and off the roof rack. The boxes were placed on the landscape fabric and then positioned using a tape measure. I messed up in the planning by assuming a 4x4 box consumed four linear feet of plot space, which is not really true because it doesn’t consider the width of the material used to build the boxes. Consequently, the row to the left of the boxes will only be 18 inches instead of the 24 inches I had planned. At least I have a nice wide path between the two boxes themselves, and I have access from the garden path on two sides.


Once the boxes were positioned, the final step was to place them on blocks. I used 4x8x16 solid blocks which were placed by lifting up one end of the box and putting two blocks into position. The landscape fabric was then covered with wood chips to protect it. Final step is to create the Mel’s Mix and fill the boxes, once it stops raining here for a few days.This should be accomplished before the Memorial Day planting frenzy. The beds will have a tomato trellis installed along the long side on the right, which is roughly north.

The boxes placed on blocks and squared up to the garden


  1. What beautiful and well built raised beds. The cedar will last a long time and 8 inches deep will definitely be beneficial for tomatoes. Yes, you can grow tomatoes in only 6-inches of mix, but they will produce more if they can spread their roots.

  2. Thanks, GrafixMuse. I filled one of the beds on Thursday and plan to finish the second on Friday, just in time to plant tomatoes and peppers this weekend. I am getting excited!

    What is amazing about SFG is its space efficiency. I planted 14 tomatoes in this space last year. With the new beds, I will have 12 tomatoes along the side with 36 squares left for other plants. That is better than adding an additional two 4x4 boxes to the garden!


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