The allotment plots in the BAUUC Community Garden will be 4-ft x 20-ft raised beds. The beds will be constructed by putting down a layer of cardboard over the ground (and weeds), installing the edging, then filling the raised bed with about 8 inches of imported soil. This is a typical approach for raised vegetable beds and is the method recommended by the knowledgeable folks at Urban Harvest.
When it comes to edging there are lots of choices – from found & recycled items to cast-in-place concrete curbs. A “best-practice” construction promoted by many sources is to use 8″x8″ hollow cinder blocks. They are durable, reusable and give a nice edge to the vegetable bed that can be used as a bench. (There are several examples in the Community Garden Tour Slideshow.) However, they do best when the garden site has been evenly graded and require careful attention during installation to keep the edges tight.
The BAUUC Community Garden design team has instead decided to use 2×10 Southern Pine lumber (untreated) for the bed edging. Lumber will not last as long as cinder blocks and requires staking to keep it in place, but it has these advantages:
- Lumber edging may be easier to install and keep properly graded
- 2×10 untreated pine is less expensive than cinder blocks – approximately $30 versus $80 for a 4-ft x 20-ft bed
- Southern pine is regional and sustainable, and untreated lumber can be safely recycled into mulch
- Deeper beds typically benefit the plantings (lumber edging with a nominal depth of 10″ instead of 8″ for blocks)
Although the short life-span is a significant disadvantage in using untreated lumber (estimated between 5-7 years), the advantages for ease of assembly and lower cost drove the selection for the initial bed construction.
If you have long-term experience (positive or negative) using 2″ untreated lumber as edging for raised beds, let us know. There is still time to consider convincing arguments before materials are ordered.