In a park near my home are the most beautiful raised garden beds ever. They’re made of reclaimed redwood, painstakingly planed smooth, skillfully fitted and joined. They’re ergonomic and wheelchair accessible, built to last.
And then there are my garden beds. They are not as pretty, but they were cheap and easy, and they have served me well.
It’s not that I’m incapable of skilled carpentry — I built my own kitchen cabinets, for crying out loud — but I’m not going to put that kind of effort into something whose sole purpose is to keep a big pile of wet dirt in one place. This is why garden beds are the best kind of building: you can adapt them to just about any budget and skill level.
You can make them from anything you like, as long as it doesn’t leach anything poisonous into the soil. That means don’t use pressure-treated lumber, railroad ties, old tires, or anything that was painted before 1978 (old paint may contain lead).
Good materials for raised beds
- Unpainted boards (2″ thick recommended)
- Bricks or cinderblocks
- Urbanite (that’s hipster for “busted-up pieces of concrete from the sidewalk / driveway / patio I took out” — stack it up like a New England wall, or jam big pieces into the ground with the flat side facing out)
- Hay bales
- Erosion-control rolls (if you’re going more than one level deep, use stakes to keep them in place. Probably not sturdy enough for more than about a foot deep.)
- Logs or a bunch of stumps (usually available for free from tree-removal services)
I recommend making beds 4 feet across if you’ll be accessing them from both sides; 2 or 3 feet if they’re against a fence.
Make them any length that works for your space. When in doubt, I recommend a couple of 4×4 beds (2×6 if they’re against a fence). The small size makes them easy to build, move around (if needed) and take care of the growing garden, but they’re still big enough to grow plenty of veggies.
- If your soil is good, 8″ deep is fine. Loosen the ground and work some compost in before you fill the beds, and plants will happily send roots down.
- If your soil is contaminated or full of glass and rocks, or you’re building over concrete, go a minimum of 1′ deep, preferably 2′ or more. Before you plant, line the bed with permeable weed-blocking cloth, so roots don’t get into the bad soil. (Did you remember to test your soil for lead?)
- Waist-high beds are great for people in wheelchairs and anyone with a bad back or bad knees.
- The taller your beds are, the sturdier they should be.
If you have the time and energy, adding a sturdy, well-supported 6″ wide ledge to the top is so very, very worth it. If you have ever spent more than ten minutes kneeling on rocks you will agree with me. A ledge is handy for sitting or kneeling on, and provides a convenient place to set your tools and notebooks and coffee.
Also, if your garden is at all accessible to small children, you will find that they like to try to balance-beam walk along garden beds, even those belonging to total strangers. A nice wide sturdy surface will reduce the likelihood that they will tumble into your beautiful vegetable patch.
Redwood and cedar are popular because they’re naturally rot-resistant. Two-bys (2-inch thick boards) are sturdy, but I’ve seen beds built from the much thinner fence boards — often available cheap at the big lumber stores, or free if you know someone tearing down a fence. Just double them up, or reinforce them every few feet.
If you don’t mind replacing the beds every five years or so, cheaper softwood two-bys will do just fine. All my garden beds are made from softwood 2x8s that I got for free on Craigslist (they’d been used as forms for a concrete foundation). After two years, they’re still plenty sturdy — some surface rot on the insides, but I don’t expect them to need replacing for another few years. And did I mention that they were free?
If your area has gophers or other digging critters — do moles plague gardeners? — line the bottom of your garden bed with hardware cloth. Chicken wire is not enough; they’ll chew right through it. Or so I hear.
If you have deer, rabbits, or cats that can’t tell the difference between a garden bed and a litterbox, try hoops and netting. You can make the hoops out of pvc pipe, electrical conduit, or anything else that’s flexible enough to bend into a U shape. Some folks screw fasten the hoops to the long sides of their garden beds with pipe clips. Others pound rebar stakes or 1′-2′ lengths of slightly larger diameter pipe into the ground, then just slip the ends of their hoops over or into them. Once your hoops are in place, drape netting over them.
Speaking of rebar…
You can use rebar or other stakes to hold the walls of your garden bed in place (with or without fastening the corners using one of the methods below). But remember what I said about calling 811 before you dig. Also, if you have an irrigation system remember that the underground pipes aren’t necessarily in a straight line with the sprinkler heads — sometimes they’re a few inches to one side or another. I speak from experience here.
The Corner Brackets Method
I made my garden beds out of free lumber (thank you, guy on Craigslist), braced at the corners with the least expensive brackets I could find. Except the least expensive brackets weren’t quite cheap enough, but the guy at the hardware store suggested I get a bunch of the Simpson Strong-Tie Tie Plates and bend them into L-shapes. “You have the strength!” he assured me. He was right on all counts.
You may, of course, use any kind of bracket you like. The construction hardware section will be the most cost-effective, followed by the handyman section, followed by the shelving hardware, followed by anything “designed” by someone with their own TV show. I put the brackets on the outside, rather than the inside, so I can unscrew them if needed, and to reduce moisture intrusion into the wood, and because I am convinced this will keep them from pulling out of the wood even if it starts to rot.
I just used one 1″ long screw at each end of the bracket, two brackets per corner. You could probably use nails, instead. After the first year I decided to reconfigure some of the beds, and it was fairly easy to unscrew one end of each bracket, shorten or swap out the boards, and reattach. I didn’t use the fancy outdoorsy no-rust screws, so a few of them broke off instead of unscrewing. I just screwed the replacement screw into an adjacent hole and called it good.
The Corner Post Method
If you want something with a little more structural stability, you can use posts at the corners. This has the added benefit of allowing you to stack multiple tiers of wood, making beds that are both tall and sturdy.
Many folks use a 4×4 on each inside corner, screwing or nailing or bolting the boards. If you’re using long spans, one or more additional 2x4s at mid-span will provide additional structural stability. This looks tidy from the outside, but you end up with corner chunks missing from your planting area, which will vex you to no end if you use the square foot planting method.
Sunset magazine has some nice plans for this style.
You can also just screw or nail the boards together, but you run the risk of a) splitting the ends of the wood, and b) having the screws or nails just pull right out of the end grain when the neighbor’s child is balancing on the edge.
Now, get outside, and build yourselves some raised garden beds!