20 Feb 2008
On a Level: The Early Days of my On-The-Contour, Raised Bed Garden.
The past couple of Saturdays I have spent happily in the garden in the worryingly unseasonal weather, beginning the process of turning my not very useful garden into something more useful, building my family’s resilience, food security and gardening ability. The garden is a south-facing slope, with about 4 inches of topsoil on top of what is gravelly clay. I have long been a devotee of no-dig raised bed gardens, but have never had to construct one onto a slope before. In my previous garden I made un-edged raised beds on the level, but in these sloped surroundings, something more substantial was called for.
The installation of our beds began last September, when I covered the area where the beds were going to go with old carpets in order to knock back the grass and weeks in preparation for digging. Then, two weeks ago, I took up the carpet and using my long level, marked out the top contour. Then from the line I measured the width of the bed based on my being able to reach into the middle from both sides. Once I had identified the bottom edge of the bed I again used the level to ensure the bottom edge also followed the contour. I then allowed sufficient width for a path and then started again on the second bed.
Why garden on the contour? There are a couple of reasons. The first is set out well in Mandy Pullen’s excellent 2004 book Valuable Vegetables: growing for pleasure and profit (eco-logic books);
>“If your plot is on any sort of slope it pays to position your beds along the contours. A contour is a hypothetical horizontal line which runs level along the side of a slope, and it is prudent to grow your crops along these lines. Growing your crops downhill (or against the line of the contour) will inevitably lead to soil loss. Even if you have good green cover, when soil is being tilled on a regular basis a heavy downpour is often enough to wash topsoil away”.
The second is the capture of rainwater. If beds are running downhill, rainwater is lost downhill as soon as it hits the ground. Gardening on the contour means that water is held up and allowed to percolate into the bottom of the raised bed, reducing the amount of weeding required. Raised beds are great in this system because they are always building soil, being high enough to discourage their being walked on, and once prepared, aren’t dug, rather fresh compost is added to the surface on a regular basis.
Once I had marked out the beds, I dug out the topsoil from the paths and put them in upside down on the downhill side of the beds. By digging a path down the side of the beds, I was able to gather enough soil to bring the beds up level all the way across. In time the turf will die off and add fertility to the bed. Once the bed is finished I will add 6 inches of compost on the top.
Once the paths were done, I began to build the raised beds themselves. I used fairly light wooden pegs on the uphill side of each bed, but on the bottom I used stronger posts as they would need to hold back a greater weight. I used stronger fencing posts here. Then I used 6 by 1 boards to make the bed edging.
They look great I think. Very substantial and in sympathy with the shape of the landscape. I’ll keep you posted on progress as we get to the stage of planting them up. It is great, after a couple of years in a gardenless wilderness to finally be back, able to garden, to get hands into the soil and to plan for the future of a garden. I told my 14 year old son the other day that he wasn’t allowed to leave home until he has mastered the growing of 10 vegetables to a basic level of proficiency. We start his training this year! His first crops? Peas, lettuce and beans. We’ll leave sweet corn for a year or two…