- Protect the growing medium
What are raised beds? A raised garden bed is one where the growing area is lifted above the surrounding soil. This can be anything from 10cm (4 inches) to a metre (3 feet). The material used also varies from straight compost to mixture of materials layered one upon the other. I would avoid mixing these layers. Mixing soil layers is not a natural process, by and large. Nature layers, humans blend, is a good rule of thumb. The idea behind this entire website is to mimic nature as much as possible rather than repeat the practices that got us to where we are.
The first two and most obvious reasons for going to the trouble of building a raised bed are: no digging and no weeds. These are reason enough for me and maybe you too. The benefits are profound. By not digging we do not move weed seeds to the surface, we allow the structures in the soil grow and strengthen and we mimic nature.
Other benefits include better water usage, more biological activity in the soil and the creation of a carbon sink.
There are a few variations available to the gardener. In the process I use they all include cardboard as the base level. I used to include newspapers but these are much harder to get hold of these days as newspapers go digital but if you have access to them, use them.
After the base layer your choices come down to a couple of things. The availability of materials is the main constraint. What we are looking to create is deep litter. Ideally I would fill the bed with compost or vermicompost (earthworm material) and then cover the surface with a protective layer. This can be straw, wood chips or even shredded paper.
Another alternative is to place the wet cardboard then cover it with straw. Open the straw, make a cut in the cardboard and plant seedlings/seeds directly into the soil. This works well but you need to keep an eye on the possibility of weeds sneaking in through the cut in the cardboard. Another variation on this uses 75 cm (2.5 feet) of straw with potatoes placed directly onto the cardboard. This is a great way to start but requires good boundaries. Netting, wooden boards and such like to keep the straw in place. The straw should be thick enough to stop sunlight reaching the spuds and turning them green. Harvest is easy, lift the straw, collect your spuds.
With any of the approaches, the effect is to stop weed seeds from germinating, it provides a great growing medium for plants and protects the biology of the growing medium from the effects of wind, direct sunlight and rain run off.
This is the simplicity of the system, once you have the materials together.
- Soak cardboard for an hour in water.
- Select area of lawn, bare earth etc for creation of your raised bed.
- Slash any existing lawn and say goodbye to it forever.
- Lay the cardboard/newspapers out in the desired shape of your bed.
- Cover to a height of 8 inches with deep litter.
- Add worms if you have them, at dusk.
- Cover with straw, wood chips, shredded paper.
- Next morning plant out with seedlings.
And that’s that. Your raised bed is up and running.
As mentioned above, deep litter is the growing medium. This can be any of the following:
- Animal bedding
- Layers of Lucerne (Alfalfa) hay, compost, straw
- Just straw