Using pine will last for a few years and is relatively inexpensive at about $,70 per linear foot for a 10-foot-long 2 x 6 pine board. Cedar is another good choice that will give you many years of use and it is rot resistant. It is a bit pricier at about $1.87 per linear foot for a 12-foot-long 2 x 6, but it can last twice as long as the pine lumber and is readily available at your local Home Depot.
One of the steps you can take that will help your Pine or Cedar lumber last longer would be to dig a trench around the perimeter of your proposed raised garden site. Make the trench about 3 inches wide by 6 inches deep. Fill the trench with compacted crushed gravel. Once the crushed gravel has been compacted, set up your raised garden bed along the center-line of your compacted crushed gravel bed. The gravel will aid in drainage around the base of our boards.
Using a pond liner inside your raised garden bed will also help to keep the moisture away from your raised garden 2 x 6’s.
I have read posts from gardeners who have used untreated cedar lumber for their raised garden beds and have had them last 10 years. For a little extra cost up front, yet still very affordable, cedar lumber looks like a good choice for your raised garden beds.
The Home Depot has an Eco-Wood treatment available that will also help to increase the life of your raised garden bed and it is also available in California.
Be sure to take pictures of your raised garden bed project and share them with us at:
Please let us know if we can be of further assistance.