This spring I built two large beds of equal size that were each made of three smaller beds. The total square footage of the beds is around 144 square feet. It's really just little smaller since I reduced the long beds by a couple inches each on the sides. The corner beds are 4'x4' square planters while the the beds that connect to the corner bed are roughly 4'x8' and 4'x6'.
I began by purchasing non-pressure treated pine wood. In my opinion the best material to use for raised beds would be stone but wood has an economic advantage. In the realm of wood the best wood to use would be a cedar or a redwood since they resist rot and insects pretty well. I didn't use either of these because of the price. Either one of these would have been about 3 times what I spent on the pine. The pine won't last forever, in fact in may only last 4-5 years but by then my garden design may be ready for a reinvention, or maybe I'll be able to afford stone.
I began by making the 4'x4' box. I used two 2'x10's to make each corner bed. I could have used a corner post 4"x4" in each of the corners for stabilization. It may have made it easier to put together but I was trying to "cut corners." (Yep that's a pun alright.) I pre-drilled holes in the last inch of each board that would connect with the end of the adjacent board. Then I drilled deck screws through. Deck screws are plastic coated to help resist degradation caused by the weather.
On each end I drew a pencil mark to guide where I drilled the holes. I used a scrap piece of lumber as a template for the pencil mark.
Here you can see the three holes I drilled into the lumber.
I stood the board on its end and connected the next piece to it through the pre-drilled holes.
After the corner beds were built I connected the long 6'x8' pieces to the corner beds with deck screws through pre-drilled holes. The boards for the long beds are slightly shorter than 4' to make connecting them to the corner bed easier. Pre-drilling makes everything easier! Again, I could have used 4"x4" corner posts to connect the beds but instead I chose to screw them directly together. Since these beds aren't going anywhere for a while they should be stable enough for what I need.
I capped the long ends with a 4' piece of lumber.
Here's an overhead view shot from an upstairs window in my house.
After the wood was assembled came the fun part, the filling! To kill off the grass underneath I used a layer of cardboard and newspaper. I gathered up grass and covered the newspaper and cardboard. Then came more newspaper followed by compost and topsoil. I put the compost under the topsoil to encourage the roots to grow deep when I plant the beds. The grass on the bottom layer will decompose and add nitrogen to the mix. In the fall I'll cover the beds with shredded leaves and grass clippings to protect the soil. I may even plant a small cover crop like clover to invigorate the soil, but that's a subject for another time.
The layout of my vegetable garden has changed many times now since this was originally posted! Here's what my latest raised bed vegetable garden layout looks like - although the transformation is not complete.