How to Use Fir Boards for Raised Garden Beds

Fir is an excellent choice of material for a raised bed. It's as easy to work with as pine, but lasts longer. It avoids the risks of using treated lumber in a garden. Old treated pine leaches arsenic into the soil, new treated pine may leach arsenic and copper. Railroad ties leach creosote. The exterior of a fir raised bed will take any wood stain to make it complement its yard environment. These instructions make the standard 4 foot by 8 foot raised bed.

Things You'll Need

• Tape measure
• 4 stakes
• 20 feet twine
• 3 pieces 2 by 12 inch Douglas fir, 8 feet long
• Square
• Circular saw
• Level
• Shovel
• 8 L brackets
• 32 screws
• Screwdriver
• 1 cubic yard compost
• 1 cubic yard peat moss
• 1 cubic yard sand or coarse perlite
• 2 cubic yards soil
• Garden rake

Instructions

1. Locate a spot for the raised bed. Try to find a level spot that gets at least six hours of sun a day during the growing season. To maximize sun exposure, orient it north/south. If you plan a trellis in the bed, orient it east/west.

2. Measure a rectangle on the ground 8 feet by 4 feet, 4 inches. Drive stakes in the four corners and tie the twine to the stakes. Remove all vegetation, including roots, from inside the string. Remove the stakes and twine.

3. Cut one board in half. Place the two short boards vertical at the short ends of the rectangle. Place the two long boards vertical on the sides. Put the level on all four boards. If not level, adjust the ground with the shovel.

4. Screw four L brackets near the top of all inside corners. Check level again and adjust if needed. Screw the remaining L brackets near the bottom of all inside corners.

5. Turn the soil inside the box to the depth of the shovel blade. Pour a small portion of the compost, peat moss, sand and soil into the bed maintaining the ratios. Mix it with the rake, slightly incorporating it into the soil below. Add more and mix. Repeat until it's all in there. Smooth the top with the rake, contouring a peak down the center.

Tips & Warnings

• Don't layer the planting medium. Mix it thoroughly.

References

• Complete Raised Bed Guide
• Construction Tips
• What to Plant and How