When it comes to actually filling the raised garden beds, sometimes the ideal gives way to other pressures. Ideally I would build the raised bed frame then fill it with varied layers of nitrogen rich and carbon rich. Sprinkle on activators such as blood and bone and add trace elements through rock dusts. I would let it sit for several months and encourage the chooks to turn it mixing it more and adding a little extra chicken manure.
Because of the circumstances of my move I found myself building garden bed when we were already half way through spring. I needed to build some beds fast, and get some veggies in if I was to have anything growing this summer. I also had little spare cash after the expense of moving, so buying material in was mostly out of the question.
Adding layers of nitrogen and carbon materials
I gathered what I had available, used straw, grass clipping, weeds, dried leaves, some rich top soil which also contained lots of tree bark (not ideal), kitchen scraps. I layered and mixed it as well as possible, watering it as I went. I did buy a coir block and added that to one of the beds. It did take me some time to gather all this, I started collecting and layering the material before I had even built the frames, and the first bed got a considerable amount of rain during the process.
When a raised vegetable garden bed is made out of treated or unknown timber it is important to line it with plastic. Otherwise the poison used to treat the timber will leach into the soil and be pick up by your vegetables. But this can be a fiddly business, especially if there is any wind about. I find it useful to have some material already in the bed to hold the plastic in place as I line the walls of the bed.
Adding a plastic lining for the walls.
Initially, whilst still constructing the walls I had heaped material in the centre. When I was ready to line the frame I spread it out and added straw, until it was about half way up the walls. I pushed the straw back just far enough to line the walls with plastic, where possible I wrapped the plastic around the top piece of wood or anchored it behind a post. In this way I was able to hold the plastic in place with one hand and push the straw back onto it with the other. After that I added a layer of nitrogen rich grass clippings.
One handy trick if you wish to plant into a bed that is not ready is to make a hole, fill it with compost and plant your seedlings into that. Similarly a layer of compost on the top to plant your seeds into works well. It takes several weeks for the seeds to germinate and the roots to grow beyond the compost, by which stage the soil components have broken down further. But I hadn’t been here long enough to have any compost.
Purchased vegetable garden soil as the top layer is my compromise.
There was only one option left if I was going to get anything growing this season. I had to buy in some top soil. Now I know that purchased “soil” is inferior quality, but vegetable soil is generally better than the top soil that they sell, which is usually full of household garbage. One cubic meter of soil doesn’t go very far in raised garden beds, but if its only 20cm deep it should cover 5 square meters.
I bought some “vegetable garden soil” which turned out to be a mixture of cow manure, sand, composted bark and who knows what else. The cow manure should help things along a bit. As I moved it I discovered not only does it contain lumps of bark, but lots of stones as well. I filled the top of the beds with this purchased soil.
The final touch was to hide the plastic that was showing at the top edges, not only is it unattractive, it will harbour slugs and snails which would come out at night and eat my precious seedlings. My raised beds were complete.