Extension Educator, Horticulture
"What goes around comes around" Wedge shoes, capri pants and leg warmers. Let's hope polyester leisure suits are gone for good. Some sound gardening techniques such as raised beds have seen resurgence with good reason.
Raised beds offer definite advantages to traditional row vegetable gardening.
Improved production – Raised beds can produce twice the amount of vegetables per square foot than traditional gardens since vegetables can be planted at higher densities. There is no need for wide spacing since walking or tilling between rows is not necessary.
Aids in soil improvement - Got lousy soil? The addition of ample compost and better quality soil to the beds can alleviate lousy soil issues. Soil compaction can be a particular problem with clay soil. Tractors, tillers and even human feet can compact soil making it difficult for plant roots to penetrate and for water and air to move through the soil. Soil compaction can reduce yields up to 50 percent. With raised beds tractors and tillers are not needed and because beds can be worked from both sides there is no need to walk in the growing area.
Improves soil drainage – Areas that tend to flood can become gardenable with the addition of raised beds.
Adds refinement to the landscape – Well-constructed raised beds look neat and tidy without much effort on our part. Flowers along with vegetables can add a spark of color.
Improves the gardening experience – Gardening is supposed to be fun. The taller the raised beds the less we have to bend over. Since spacing is reduced, there is less room for weeds to grow.
Expands gardening season – Raised beds tend to warm earlier in spring and stay warmer into fall. You often can plant earlier and harvest later. In addition because of their compact size beds can be easily covered with plastic to extend the growing season. Since the beds drain well gardeners can plant sooner after a rain.
A few tips in building raised beds:
Raised beds can be unframed with a mound of soil; however the height of the raised area is limited to 4-6 inches before the edges start to drift.
Beds can be framed with just about anything available such as cinder blocks, stones, bricks, recycled plastic lumber or wood. If your bank account can handle it, redwood or cedar can be used. Treated wood is fine to use as long as it was purchased after 2004 when the EPA banned use of arsenic treated lumber for residential use. Now copper is the main ingredient. If any copper leaches to surrounding soil it is quickly bound in soil particles. In addition plants are less tolerant than we are to copper so the plants would die well before copper in plant tissues could get high enough to cause us chronic health problems from eating the plants.
Keep beds narrow. Most people can reach 2 feet without much effort; therefore beds 4 feet across allow easy access from both sides. Four foot wide also works well with common board lengths. For instance an 8x4 foot bed can be made from 2 twelve-foot long boards.
North-south orientation is best for low-growing crops. Beds intended for taller crops such as pole beans, trellised peas or caged tomatoes may be better on an east-west axis since lower-growing crops could be planted on the south side of the bed and still receive full sun.
Pretty much any plants can be grown in raised beds. Some vegetables will overwhelm a small raised bed unless trellises are used. Supports for poles, cages and trellises can be easily mounted to the frame.
The biggest disadvantage to raised beds is the initial expense and work to build and fill a framed bed. However a well constructed bed should last for years.