Many MWG readers use raised beds in their vegetable gardens. I do too – raised beds have so many advantages for the home vegetable gardener that is is hard to imagine gardening any other way.
As good as raised beds are, however, they do have some disadvantages. I feel that the advantages of raised beds completely outweigh the disadvantages, but it is still a good idea to know the what the limitations are. I have outlined a few for thought and discussion below:
Drainage – Raised beds drain very well vs. conventional beds and that is actually one of the best reasons to convert to a raised bed system. During wet times and in the spring at planting time raised beds are the way to go! But during the heat of summer when water is less plentiful raised beds often dry out much quicker than a conventional bed would, leading to stress, increased disease susceptibility and reduced yields. If drying out is a problem for you then supplemental watering and mulching might be the best solutions.
Poor Air Circulation – Typically we grow things closer together in a raised bed system to maximize our planting space and yields. Normally this isn’t a problem, but if the plants are too close together the reduced air circulation can cause diseases because the plants remain moist longer. I had this exact problem in my lettuce patch this year – the plants were so close together the bottoms never dried out and they ended up rotting.
Cost – Raised beds aren’t necessarily cheap. Unless you have several cubic yards of soil sitting around you will have to purchase enough to fill in the beds. The beds will also need some sort of edge to help contain the soil, typically wood. I tried beds without any edging last year and the experience was so poor I spent about $100 on wood this year to get the beds framed in.
Inflexibility – Plan your garden well — once you have your beds set up you are pretty much stuck with them the way they are. Moving a raised bed can certainly be done, but it isn’t something to do on a whim. I’d guess moving a 4 x 8 foot bed would take well over an hour, more if you have things like fences or gravel paths to deal with.
Some Plants Sprawl – Raised beds and plants that sprawl like pumpkins, gourds, winter squash and others don’t mix well unless you have come up with a solid support system beforehand. The vines tend to go wherever they want, and more often than not end up in the walkways. That might not sound like a big issue, but typically we try to minimize the walkway space in a raised bed garden to have more room for the beds themselves. This year I have a yellow squash plant (see photo at right) that has overgrown the bed into the walkway and basically has shut down that path to foot traffic (it is too big to move out of the path and if I cut it back the plant will die).