There is much debate around the “ideal” size, shape and type of garden bed. As a gardener who is always looking for practical, affordable and effective gardening solutions, I tend to stick to a couple of garden bed types.
My first preference is to work directly with existing soil – if it is not contaminated, infested with rodents, or covered with pavement. If the soil is contaminated, infested with rodents or paved over, I always recommend raised beds.
Half wine barrels are excellent planters that are fairly long-lasting (+/- 10 years). They work well for small perennial shrubs, veggies and herbs. I’ve even got a 20+ year-old Meyer lemon tree in one and it is still happy and productive.
If you are going to build a raised bed, be sure to use a long-lasting kind of wood. Salvaged redwood planks are the best option but they are often hard to find. Douglass Fir and Pine should NOT be used as they decompose quickly when in contact with biologically-active soil (lasting less than 5 years, oftentimes). Broken concrete or “urbanite” also works well.
For school gardens, I like a 3×8 ft bed raised bed. It is large enough to produce a significant amount of food, students can reach to the middle of the bed from both sides, and it is large enough for about ¼ of a class to work with at a time (roughly 8 students).
We built one yesterday with the students and community volunteers at Giannini Middle School and I thought I’d share the photos to show the sequence of what we did. They have a really bad rodent problem, so we lined the bed with welded wire mesh and hammered “U” staples in to attach the mesh as well.