DIY Garden Box

1. Choose Your Lumber

   While cedar or redwood is the best lumber to use, as they are the most rot-resistant, these may be more than you want to spend or hard to come by in the size you want. Spruce or pine will rot more quickly, but experience shows that you can get 10 or more years of use out of them. Do not use pressure-treated wood, as it is treated with chemicals you do not want in your soil or in your body. (Pressure-treated wood used to be treated with arsenic, but more recently copper is used.) You can also use fiberglass or other artificial materials, which will last longer but cost a bit more.

2. Test Your Soil

   If you plan on eating anything that you grow, have your soil tested first. Even if you fill your bed with all new soil, if the bed is set directly on the ground, inevitably some of your plants' roots will find their way to the original soil. Have your soil tested for lead and other contaminants at the cooperative extension at your state university. 

3. Measure Your Space

   Find and measure an area with a full day of sun (essential if you’re growing vegetables or most annual flowers). 

4. Determine How Much Soil You Will Need

   This plan is for a raised bed that's four feet wide, 10 feet long, and nine inches deep. (While your side boards may be 10 inches deep, you don't want to fill the garden box all the way to the top.) Multiply all three dimensions to figure out how much soil you'll need: 4' x 10' x ¾' (9 inches) = 30 cubic feet. Garden soil is usually sold by the cubic yard (27 cubic feet), so buy a yard of a good soil mix, plus a few extra bags of compost to complete your soil purchase. (To save money, purchase less soil and fill the bottom layer of your raised bed with fallen leaves. They decompose slowly and improve the soil.)

5. Roughly Assemble Your Sideboards

   Make sure each of their ends meet. 

6. Secure Your Boards in Place

   Drive your 2” x 2” wooden stakes into the ground at the four inner corners of your raised bed. Ensure 10 inches remain above ground, flush with the side boards. From the outside, screw three 3-½ inch deck screws through the side boards into the wooden stakes. (You may want to either brace the side boards with some scrap wood or get a helping hand to hold them in place.)

7. Line the Bed

   Line it with plain cardboard and/or multiple layers of plain newspaper to block weeds. Be sure it's plain, as colored paper or cardboard will leach chemicals into your soil. Wet down the newspaper to prevent it from blowing around. (A longer-lasting but more costly option is weed-block fabric, which you can purchase from garden centers.)

8. Cover Your Weed Block

   Use fallen leaves or composted cow manure. Because it's composted, the cow manure doesn't smell and handles just like dirt.

9. Fill the Bed With Soil/Compost Mix

   Smooth evenly. Use a plumb line to level the soil to assure even drainage. Water everything in.

Additional Options and Design Ideas

• Add 2" x 10" cap boards to create around the edges of your raised bed.
• Instead of wooden stakes, you can also use eight galvanized L-brackets. Your garden center may also sell brackets made specially for building raised beds. If you're using L-brackets, attach two evenly spaced brackets on each inside face of the side boards with 1-½ inch deck screws.
• Grow vining plants, like peas or beans, by attaching a wooden trellis to the end of your raised bed that's farthest from the sun. This way, the vines won't shade out your other plants.
• Build a cold frame to cover a portion or all of your raised bed to extend your growing season. (Plastic ones can also be purchased.)
• Raise the height of your raised bed by doubling or tripling your dimensions.
• Amend your soil with bone meal or other organic supplements as needed.