Raised beds are an interesting topic, mostly because they, like so many things really depend on your situation. Several years ago raised beds were the hot topic and everyone was talking about how good raised beds were and while I was in the landscaping business we built quite a few for people.
If you go onto many other farming or homesteading sites I’m sure there will be many pictures of raised beds and there will be praise going along with them too.This is a raised bed I made out of mountain stone several years ago.
These beds are from somewhere else made from treated 2×6’s.
There were a couple of reasons I made my mountain stone raised bed, one of which is that I like working with mountain stone and this stone was in the way so I made a bed with it, another reason was to make a defined bed (neither of these ideas had a good focus on growing).
The two beds with treated wood were primarily made because the on site soil is clay.
Between my bed and the other two beds the ones with the wood make more sense because better soil was brought in to give the vegetables 6 inches of good soil to grow, where as mine didn’t get much of an advantage other than the addition of horse manure.
From my understanding the original raised bed was not actually contained by anything, it was actually like a small swale, this had three immediate advantages, the first was that if you had a limited space like in many places where subsistence farming takes place, by creating the curve you were increasing surface area for planting (neither of the raised beds pictured accomplishes this). Secondly because of the swale there was possibly increased air flow through the mound (the mountain stone bed has this advantage a little but not the beds made of treated wood). Third better soil or compost was brought in to make the mounds (this was the case in both pictures here, with the mountain stone bed horse manure was brought in).
There are problems with raised beds too, they can be harder to work, neither of these pictured beds are as easy to get a tiller into if used as on the ground and generally they dry out faster which could be good if your soil is very wet but mine got hurt really bad during the drought last summer because I was afraid to water.
With the treated wood beds, and many are made of cross ties, the chemicals in the wood can and do leach into the soil with your crops, plastic lining could be put in but if too much water is held in the bed could either blow the walls out (if they were taller than pictured), or just hold too much water in and cause a rotting problem.
In hindsight the big advantage the mountain stone bed has is that I have no noticeable erosion even though a lot of water runs through the area after heavy rain fall.
In my opinion there can be advantages to raised beds but there can also be many disadvantages, a raised bed without a real purpose is a waste of time and energy and may be counter productive. In the right situation they can be very beneficial.
Don’t make a raised bed just because it sounds cool, if you do you may pay for it in the beginning and the end, food for thought on an idea that many people believe is the best thing since sliced bread, every situation is different make sure you know why you are making a raised bed if you choose to make one.