Raised bed gardening offers several advantages over normal ground-level gardens.
It also offers several disadvantages that have to be taken into account in the planning.
To begin with however, raised bed gardening means you build an enclosure and fill this enclosure with soil.
You can make the enclosure as high as you desire.
Remember that if you build the walls high enough for wheel chair access, those walls will be holding back an immense weight of soil and will have to be built strongly enough to handle that pressure.
Raised bed gardening advantages include:
The ability to eliminate stooping over to weed and work with the plants. For those with the inability to kneel or bend over, raised beds are well worth considering.
Raised beds allow the gardener to escape their natural soil limitations and create a super-soil in the enclosed space that will grow anything. An enclosure is treated as if it were a container instead of a garden soil. A raised bed is simply a giant container garden, and it follows almost the same container gardening rules
Soils in slightly raised containers, only a few inches over the soil level, can easily be filled with garden soil. However, the taller the garden and the more intensive the gardening, the more there is a need for an artificial soil.
Raised beds warm up earlier in the spring and vegetables can get a head-start when grown in a raised bed.
Watering Problems with Raised Beds
Having said all that, it is important to note the following:
Raised beds demand more water than in-ground beds. Water drains from them faster and success depends on watering more often than for in-ground flower beds.
Because of the increased watering needs, extra compost or organic fertilizer is required (the extra water takes away more water-soluble Nitrogen) than with in-ground beds. Again, this is a feature of container growing.
Perennial plants in raised beds are more susceptible to winter damage because their roots are above the soil line. Tender plants should not be grown in raised beds in colder areas. This unfortunately means that those gardeners who want to use raised beds to substitute for heavy clay soils will have trouble growing tender plants in those beds. The solution is to grow hardy plants there.
Construction of raised beds has traditionally been accomplished by building a rectangular enclosure of the desired size. I’ve made them from concrete building blocks (and then planted the holes as well as the enclosure) as well as railroad ties, cedar logs, and laid stone.
This however doesn’t mean they have to be square – a contained bed can be any shape you want. One important consideration is width.
One has to be able to reach from side to side in raised bed gardening. There is little point in having a no-man’s land in the middle of the bed that nobody can reach. Access from both sides means the bed can be wider than if access is only available from one side.