Since my structure will be used exclusively as a raised flower bed, I built it with pressure-treated lumber. A long-lasting product, pressure-treated lumber is a relatively inexpensive material for building raised flower beds. For raised garden beds devoted to vegetables, however, opt for a wood such as cedar, instead (stone and cinder blocks are other alternatives). Pressure-treated lumber contains preservatives that you probably don't want to have near food crops.
Pressure-treated lumber used to contain CCA (chromated copper arsenate) or ACA (ammoniacal copper arsenate). Responding to concerns about the existence of arsenate (arsenic) in pressure-treated wood, in 2002 the lumber industry let it be known that they would soon be rolling out an alternative product, which makes use of a different preservative.
The alternative pressure-treated lumber is called ACQ and is preserved with alkaline copper quaternary. ACQ pressure-treated lumber contains more copper than the old CCA or ACA, but at least it's free of arsenic.
I bought ACQ pressure-treated lumber for my raised flower bed. Check the label when you shop, to determine what kind of pressure-treated lumber you're buying. But regardless of the wood you're using, for safety, you should:
- Handle it with gloves
- Wear a safety mask when cutting
- And use safety goggles when cutting
Fortunately, I didn't have to do much cutting. I had my lumber cut to the needed lengths at the lumberyard, for the most part. When you're not a carpenter, keeping such projects simple is generally a good idea, and that's precisely what I did. I needed:
- 4-foot long 4x4 posts (8)
- 3-foot long 2x12 boards (8)
- And 4 additional boards to "cap off" the raised bed
The picture above shows (right to left) an example of each.
In Step 4, I discuss how the raised flower bed will be put together....