When I started learning about vegetable growing in the 1970s, most households in my community still had a kitchen garden. But almost everyone grew their vegetables in rows. It was only in the 1980s that I first came across raised beds.
There are medieval woodcuts of plants growing on raised beds. In Ireland before the famine crops were grown in lazy beds made by spade cultivation. Growing kitchen garden crops in rows is a modern system that came from field cultivation, where the crops were tended with horsepower, alleys were needed for the horse to walk on.
By the mid 1980s there were very few kitchen gardens left in Ireland, it was the preserve of eccentrics, greenies and hippies. But many of these eccentrics (myself included) were using raised beds. The recent collapse of the Irish economy has created a boom in kitchen gardening and most of these new Irish kitchen gardeners are using raised beds.
Raised beds have many advantages over row cultivation. The space that was used making room for the horse in drills, can be set to work growing crops. When space is limited raised beds will produce a much higher yield than rows. A crop like cabbage with broad leaves when planted close will form a canopy, smother weeds and save labour.
With raised beds the soil is not dug annually. This has three major advantages, first and most importantly digging is hard, time consuming manual labour. Second soil has a very complex microbial flora and fauna, with some microbes living close to the surface and some living deep. Digging inverts the soil, burying the surface life deep and bringing the deep life close to the surface. Disturbing the soils microbial life will not enhance productivity.
Third, fertile soil contains a vast bank of weed seeds. To germinate, a weed seed must be close to the surface. Every time the soil is dug a new crop of weed seeds are brought close to the surface, controlling these weeds after they germinate is a major job. By not digging, the weed seeds are left buried and the only weeds that need control are those that land on the surface of the bed.
In the damp Irish climate slugs are one of the most serious pests in the kitchen garden. They can devastate a bed of seedlings in a few hours. My raised beds are concrete and surrounded by concrete paths. There is no problem with slugs, because there is no dark, damp place for them to hide during the day. This is often not the case with timber beds, timber expands and contracts as it get wet and drys out. This can cause a small gap to develop between the timber and the soil, an ideal hiding place for slugs.
With beds compost is applied as a surface mulch and the worms carry it down. I built my raised beds nine years ago when we moved into our current house. I have never dug them since and do all cultivation with a hand fork and trowel. A few hours of leisurely work in spring and the ground is ready for planting, rather than many hours of digging, forking and raking.
Raised beds have only major disadvantage, it takes a lot of extra work to build them the first year. But this extra time is amply repaid in subsequent years, provided the beds are made of some long lived material like concrete or brick.
