Raised Bed Gardening - Pros and Cons

Many people are drawn to raised bed gardening for several reasons.  In addition to the fact some areas do not have sufficient soil, raised bed gardens generally look nice and appear easy to maintain. In many parts of the United States, reasons for building raised beds are to keep gophers out or to have warmer soils in the early spring after the winter thaw. For portions of the Hawaiian Islands, gardening in raised beds or containers is necessary because of a lack of soil on lava hardened  terrain.  

Other reasons for building raised beds are 
 (1.) the soil may be extremely alkaline (a high pH) or acidic (low pH), 
 (2.) the soil is too compacted,  
 (3.)  the gardener needs wheelchair access and
 (4.)  the gardener prefers less stooping.

On the other hand something to consider is the maintenance of raised beds. If the frame is made of wood, it will eventually rot. If metal is used, it may rust. Actual construction of the bed can be time consuming and costly. In addition to wood, rock and plastic can also be used.

Two questions often arise. First, how deep to make the beds?  The literature gives a range of 6” to 18”.  Crops like lettuce, onion and bok choy will do fine in a shallow bed. Yet deeper beds are needed for carrots, parsnips, corn and tomatoes.  

Secondly, where to get good soil? You can buy bagged potting mix at the garden store, which can be very expensive. Or you can buy a truck load of soil but be cautious. Soil may look good, but you can’t see N-P-K deficiencies or excesses, pathogenic fungi, bacteria, nematodes or pesticide residues including persistent herbicides. Bringing in soil can be risky.

Installing raised beds can be a satisfying project. But first, find out what your particular problem is and why you are considering a raised bed. Perhaps correcting the problem could be a better solution, possibly cheaper and less time consuming.

Photos from University of Missouri.