How to Build a Square Foot Garden

This post will show you everything you need to know to build your own cubic foot garden. I encourage you to build your garden to the size that fits the spot and design intentions for your garden.

It is easy to build the box used for your garden. Mine did not come from a kit but rather was built with supplies from the hardware store.

Wood: I chose to build it with rough Cedar 1×6 lumber. I did this to maximize beauty and minimize the material cost while building from a durable and lasting material. You can build it out of other materials, some of which I list below with the pros and cons for each:

Cedar: Pros:Long lasting, will last for 7-10 years, beautiful, with a middle price range. Cons: Some report that Cedar is allelopathic, meaning it may exude oil or other substances that reduce growth in other plants. I haven’t seen any evidence of that in my garden but I have never compared Cedar to other materials to verify. Another possible con is that the wood may split if dry during the construction of the box. I recommend therefore pre-drilling holes before screwing the box together.

Pine: Pros: Low cost material that is readily available. Cons: Will rot relatively quickly and may last only 3 years in the ground. One way to extend the life is to coat it with Linseed oil.

Composite Plastic Deck Boards: Products like Trex or Timbertech. Pros: Very durable and long lasting. Some offer 25 year warranties for use as decking. Cons: Usually thinner than 1×6 and may therefore flex more under the pressure of the soil. It is a heavier material and therefore may be more difficult to work with at the time of install. It is more expensive than wood.

Hardwoods: Oak, Pecan, etc. Pros: Durable and strong. Cons: Will still rot eventually, expensive.

Once you have chosen your material, you will need to decide on the size of the box. I built mine at 10 feet by 4 feet. The main design consideration will be the need to be able to reach the plants from either side of the bed, and not to make it so long that it takes a long time to walk around to the other side.

Parts list:
Buy your boards to be 1.5-2.0 feet longer than you need. The reason will become obvious in minute.
To build a 4×10 cubic foot garden, you will need the following:
4 – 1″ x 6″ x 12′ boards (for the long sides)
3 – 1″ x 6″ x 6′ boards (for the short sides)
56 – 1.5″ Wood Screws (preferably deck screws from a weather resistant material)
24 – 2.5″ Wood Screws (deck screws)
3 – 3/4″ x 3/4″ x 10′ strips (used to mark out your cubes)
9 – 3/4″ x 3/4″ x 4′ strips (used to mark our your cubes)

You will need to be handy with a circular saw (get help from someone who knows how to use one if you are not comfortable with tools like this. Also, you will need a Power Drill with a Philips head fitting to screw in all of the screws.

First cut the 12′ boards down to 10′. You should now have 4 10′ boards and 4 2′ leftover sections. Cut the 4 6′ boards down to 4′ each. You should now have 4 4′ boards and 4 more 2′ leftover sections.

Take the 8 2′ leftover sections and cut a point into each one about 6″ deep per the figure below:

Next, Attach the pointy sections as per the drawing below. For each long side board, attach 3 pointy sections to add stability. Use 4 1.5″ wood screws to attach each pointy section to each side board. It is easiest to do this on a large flat surface like a driveway. You may need the help of another person to keep the boards straight. It is important to leave a 3/4 inch gap on one side of the long boards to allow for a proper fit of the side boards. This will become more obvious when you go to assemble the unit. See the drawings below for insight on how to do this.

You will now have the sides complete. Pre-drill 3 holes in each board, 6 for each connection from long side to short side. This pre-drilling will prevent the board from cracking. You will need to pick a drill bit that is slightly smaller than the screws you have purchased. See the drawing below for where to screw the holes.

Now the next step is to attach the sides to each other. You will need a friend to help hold up the wood so that you can screw the box together. Be careful with the pointy parts of each side since they will poke you if you are not watchfull. get a long side and short side and position them with the pointy sides up and form a 90 degree angle with the side board sitting in the 3/4″ gap you created in the long side. See drawing below for the concept.

Repeat this for the two remaining pieces. Now you have two “L” shaped pieces. Now fit these two pieces together with the help of a friend. The end result will look something like the drawing below:



You will next be ready to place the complete box in the location of your choice. Go to the Location Selection link, the Location Prep link, and the Soil Prep link to prepare the rest of your cubic foot garden.