People are always interested in building raised beds. Like any gardening project, there are pros and cons to all options. Here are the upsides and downsides to putting in raised beds and some things to be aware of that will help keep them in good condition for the long run.
First, consider the materials that you will be using in the construction of a raised bed. Oftentimes people will go with the least expensive wood option (usually pine or fir). This, however, is not the best choice for durability. Since raised beds hold large quantities of frequently moist soils, fir and pine boards are prone to rot from the inside out; often degrading in a matter of two or three seasons. Since replacing rotted boards is very difficult without removing large quantities of soil from the interior of the bed, it is better to spend a little extra money at the beginning of the project to purchase rot-resistant wood (such as cedar) or a manufactured product (such as Trex). Sometimes, people will treat pine or fir with a wood sealer in the hope that it will eliminate the decay process. This only delays the inevitable for a short period of time and also exposes your soil to unnecessary chemicals. Under no circumstances should you use railroad ties or treated wood for vegetable beds. These products contain hazardous anti-fungal agents that should not come into contact with soil that is used for growing produce.
Second, consider why a raised bed is advantageous in your circumstance versus an in-ground garden. One reason that a raised bed may be a suitable choice is the need for soil remediation. Most of the greater Wenatchee valley has transitioned from old orchards into housing and lawns. As a result, residual chemical residue may remain in the soil (arsenic) from previous land-use practices. Raised beds allow you to garden above this contaminated soil and essentially gives you a ‘fresh start’. Also, with proper pre-construction planning, the bottom of a raised bed can be lined with galvanized steel hardware cloth which can keep pests such as gophers and moles from reaching your tender carrots and baby beans and peas. An unwanted side effect of a raised bed is that it can be difficult to keep weed free if proper care is not taken during installation. Stubborn grasses tend to find a way to wind their roots through the cracks and seams where the corners of the bed meet. It can be very difficult to remove all of the grass runners once they become established. It also takes extra effort to maintain the outer edges of a raised bed. For a neat appearance, careful weed whipping is needed to avoid damaging the side boards. An alternative approach is to create gravel pathways between multiple raised beds. This is easier to maintain than a lawn pathway.
Finally, a last consideration is performance. For those who have mobility or flexibility issues, it is possible to build raised beds that are elevated and within easy reach of a person who cannot kneel or is confined to a wheelchair. The trade-off to this is that the garden itself is limited in area to that of the raised bed. There is no easy way to expand the garden once the beds are built. Raised beds also require that the gardener maintain a healthy soil and add nutrients often to keep the raised bed fertile. Without regular attention, the soil can become ‘tired’ and less productive.
Whatever type of garden you create for yourself, may you find hours of enjoyment from your decision. Happy Gardening.