Building a Square Foot Garden Box (Vinyl)

I decided that 6″ was not enough soil for me, so I’m upgrading to 12″ boxes.  I found out my old boxes will not “mix and match” with my new vinyl materials, so basically I’m rebuilding them. They are 4′x4′x12″ (instead of 6″ high). Cost:

  • $27 router (on super sale! at Harbor Freight Tools)
  • ??? bit (need to pay my sister back for this)
  • $223 posts and rails (4-8′ posts, 11-16′ rails, $14 each)
  • $0 borrowed a miter saw
  • $0 jig for routing holes in posts (thanks to my talented brother in law!)

Altogether, it will cost about the same to build twice as many boxes, twice as high as it did to buy the original 3 boxes from the website. And I’ll sell my 3 boxes to a friend, and recoup a about a third of my cost.

The rails and came in 16′ lengths, so I used a miter saw to cut the rails into 4′ lengths. This was super easy.

I cut the posts down from 8′ lengths. I cut the posts to 14″–this left 11″ for the hole where the rail will go, with 1 1/2″ on top and bottom. This took at least two cuts on the miter saw, and I had to use a bigger saw that was tall/deep enough to cut it. Another option would be to use a jig saw, a table saw (it would take two cuts), a skill saw, or even a simple hack saw.

Here is my son building a “house.” His fun will be over when I actually set up my boxes!

Next, I took the posts and marked a template for cutting the holes. I drilled a hole big enough for my router blade, then put down a jig to guide my router and finished boring out the hole. You could also use a jig saw, or perhaps even a combination of a skill saw and jig saw.

 After that, it was a simple matter of assembling the rails into the holes, putting caps on the top, and filling it with soil.

Happy Gardening!

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8 Responses

  1. John Sykora says:

    I used 4×4 posts, cut slots in the posts to attach the rails. I used/cut 5 ft rails and cut a bit off the ends to make 4′ x 4′ gardens. Didn’t trust the ground to keep the rails in the posts so I used screws as stops inside the posts to make sure they stayed. Carpenter father inlaw said it was not necessary but I’m not a pro.

  2. Emily says:

    I bought whatever size posts Home Depot had, and I think they were 5×5. I don’t adhere them at all, they just go together like lincoln logs. :)

  3. Scott says:

    Thanks for putting this together. It is very helpful.

    Are those the 5 inch by 5 inch posts? I saw 4×4 at the store but not sure if they would be suitable.

    Did you use any screws or adhesive to secure the rails to the posts?


  4. John Sykora says:

    We bought our rails from Menards and Hone Depot. Home Depot’s were special ordered through the building supplies and lumber. Menard’s had them on hand.

  5. Rachel Bradley says:

    Hello, those look fantastic! May I ask where you purchased your vinyl rails? Harbor Freight? Thanks!

  6. Emily says:

    John–I bought grids from and For woodboxes, make them by putting a screw in the top every foot, then connect with kite string. For vinyl, I have not come up with a simple and easy do-it-yourself way. But my grids are dying, so I probably will have to do it soon!

    I didn’t reallysink my posts very far. I put gravel around mine, and that covers the small part at the bottom between the rail and the ground. But I did dig around the posts a little to get it level. A lot of elbow grease. :)

  7. John says:

    I noticed you did not say anything about what materials used to mark out one foot squares. What did you use and what was the cost? Also, how did you sink your posts when you placed your boxes in their homes? These are questions I am wrestling with at the moment.