Sunday, April 21, 2013

DIY Square Foot Garden (SFG): Raised Bed Construction

Bruce Posing with Hammer After Making Raised Bed
My Hero of the Raised Beds

Instructions by Bruce


After doing a fair amount of research, hubby Bruce built some raised beds with a protective hoop house over the top.  He’s made a set of raised beds once before, and made some improvements this time. An IT guy by trade, Bruce made the construction sound easy. We were both intrigued by square foot gardening (SFG), a method of dividing the garden into square foot sections and planting one crop per square foot. The space requirement for a SFG is only 20% of that needed for a conventional garden. And you’re less likely to grow more than you can eat. It’s a great method to get food variety in a small space. We’re growing beans, lettuces, chard, squashes, braising greens, dill, and cilantro, despite recent near-freezing temperatures in the yard at night. I’m sharing Bruce's method for building the raised beds and hoop house over the next three posts. I encourage you to build your own too!

Today’s post will concentrate on making the raised beds. After some deliberation, we decided to use 2" x 12" redwood for the raised beds. This is heftier than the 1" x lumber that Bruce used last time, so the beds will be sturdier and last longer. Frugal Dad uses 2" x 6", favoring lower lumber and soil costs. We wanted a deeper bed that we wouldn't need to bend over as much to harvest—remember that you’ll be harvesting from the middle of the bed as well as the edges, and that plantings will be dense. Redwood is cheapest in our area, but cedar might be a more economical choice where you are. Both are fairly bug-proof. Use untreated lumber, otherwise chemicals could leach into your organic garden.

Bottom of 4'x4' raised bed with overlapping gopher wire
Avoid This by Making 3' x 5' Bed
Our bed is 4' x 4', but this turned out to not be the best plan for gopher country. Gopher wire comes on a 4' roll. To gopher-proof, you must cover the bottom plus overlap the sides of the raised bed by 3" on all sides, according to gopher-proofing guru Thomas Wittman. This means that on a 4' x 4' bed, the gopher wire must be pieced and the overlap "stitched" or "woven" together with more wire, a time-consuming and futzy task. Make the bed 3 ' x 5' and you won’t have to overlap the gopher wire. NOTE: use wire mesh with 1" mesh or smaller, specifically for garden use. Don’t use aviary wire, which is designed for above-ground use and will disintegrate. Gopher wire typically comes on 25' rolls, and one roll will cover 4 beds, unless you have a source to buy it by the foot. To learn more about nontoxic gopher control, check out Thomas’ Gophers Limited and my previous post 12 Tips for No-Poison Gopher Control. 

If you have another method of building raised beds, please share in a comment!

3' x 5' Raised Bed with Gopher-Proofing
           
Materials & Tools:
16' length of 2" x 12" redwood
4' x 6' length of gopher wire
12 – 3" x 3/32" deck screws, redwood color
5/8” galvanized fence staples (U nails)
Newspaper (no color ink) or cardboard (optional)
Carpenter’s square
3/32" drill bit
Screwdriver bit for drill
Hammer

Method:
Cut redwood board into 2 – 3' lengths and 2 – 5' lengths, or have them cut at the lumberyard.

Diagram of Board Placement & Square Foot Sections
Stagger Corners to Get Square Foot Sections
To sure your “square foot” garden sections are square, stagger the joints on the corner of the bed where the boards come together: 5' board outside the 3' board, 3' board outside the next 5' board, etc. (see illustration). If you make the joints by joining both 3' sections to the outside of both 5' sections, your “square” foot sections will be longer than they are wide.

Lay the boards on your work surface roughly per diagram. Square one joint with carpenter’s square, and drill pilot holes for 3 screws, through the side grain of one board into the end grain of the other. NOTE: use the same size drill bit as the size of your deck screws. Drive in deck screws using screwdriver bit in cordless drill.

Repeat the squaring, drilling pilot holes, and screwing in screws on 3 other corners.

Stretch gopher wire over frame evenly. Crimp edges, making folds on corners (don’t cut wire). Hammer in fence staples every 6" or less to hold wire in place. Staple as close as possible to top of wire.

Turn bed frame over and put in place in garden. Move bed frame aside and remove weeds from where it will sit. Or if preferred, put down a layer of cardboard or 5 sheets of non-glossy black and white newspaper under bed to control weeds. Put bed frame back in place and check that it sits evenly on ground. Add dirt below bed frame as needed to level it. Put bed frame back in place.

You are now ready to fill the bed, which I’ll detail in my next post.

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