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…
20 Feb 4:08pm
I fully agree with your decision to follow the contours, but have a feeling that by making the beds level you are missing an opportunity to use your South slope to advantage. By using this slope you would increase the angle of incidence with the sun and possibly extend the season by a week or two.
20 Feb 11:01pm
I too am in the process of building a couple of raised beds. One thing I’ve been struggling with is trying to find a non-toxic wood preservative. I’ve seen linseed oil suggested but apparently it is rarely a natural product as bought from diy stores and won’t add that much longevity anyhow. I guess permanent contact with soil is going to make it very difficult to prevent rot. Any suggestions for this or do we simply have to accept we’ll have to rebuild them every couple of years?
21 Feb 12:33am
Wonderful. I too have just completed my no dig raised bed – it has taken me a year to fix it up and load enough muck into it but finally it is full enough for this year and the onions are already in. Would love to hear what you plant and your main activities, challenges, harvests and best receipes!
My only concern with mine is that we have used old railway sleepers to board it round the edges. Do these leech anything into the veg? Any particular advice or assurance anyone can offer?
21 Feb 4:14am
I seem to recall hearing a programme on Radio 4 saying they shouldn’t be used.
21 Feb 7:30am
Ideally a 5 degree slope facing south gives the best sun exposure. Usually you would work along the contours to minimise erosion losses, but thats not going to be a problem within the raised beds. Yes there are always concerns using any treated wood – the best would be untreated hardwood. Sweet chestnut is one of the better preformes in the ground and could last 15 years or so.
22 Feb 11:15am
The solution to the wood problem is NOT TO USE IT! I do not understand the recent obsession with surrounding raised beds with wood. It seems to be the first thing new gardeners do when making a veg plot and is being encouraged more and more with little thought by books and websites such as this. How much wood are we going to pile into gardens all over the country to feed ourselves in the post oil future? A sustainable solution – i don’t think so.
Problems with the sort of beds Rob has made include:
The sides dry out extremely quickly in hot weather (see if you can keep them evenly watered?)
Wood provides a lovely home for perennial weeds and slugs and snails from which it is hard to clear.
It rots unless you treat it with something nasty.
Where will all the wood come from?
I grow on a very steep slope in Sussex. We just raise our beds as you would on the flat with more raised at the top edge than the bottom edge. They then lie facing the sun as mentioned above. In very dry spells we then water by flooding the paths one at a time down the slope getting water in really deep, it works brilliantly.
This has all been worked out after having wood surrounded beds for a few years, getting more and more frustrated with them and finally ripping them out and breathing a huge sigh of relief.
22 Feb 4:55pm
If you can source them (maybe try your local Freecycle??) how about using old roofing slates to edge the beds – longer lasting than wood, which, as the above poster pointed out, does also have the habit of harbouring slugs and the like.
I originally edged the beds in my small garden with split chestnut logs sourced from a local woodlands – these lasted about 12 years. when they finally deteriorated i replaced them with scaveneged scaffold boards which I treated with some left over ‘environmentally friendly’ preservative i found in a cupboard at work. These rotted away after about 2 years. I’ve now replaced them with wine bottles see
http://www.spiralseed.co.uk/draft/bottlebeds.jpg I hasten to add that I did not personally genrate all of these, but got most of them via freecycle!!
24 Feb 10:39pm
Aaaah. The joy of knowing that I am not alone in enjoying the planting up of my new raised beds – that there are others out there sharing this pleasure. Regarding rotting and what to edge with, no ideas at all, just blissful optimism that mine won’t rot. Just put in spinach, stir fry leaves, parsley, beetroot, parsley, chives as seed, and strawberry plants today. Anyone got any good references on how to grow vertically – apart from the obvious up walls and lattices, and down in hanging baskets. I don’t have much space and the Cuba DVD – Power of Community, was strong on using all availablespace.
25 Feb 5:44pm
Hi Fi, you might want to check out Micheal Guerra’s book ‘the Edible Container garden’ which gives masses of hints and tips on such matters, and really nicely illustrated with colour photos as well.
26 Feb 6:51am
Must be that time of year! I just spent the weekend creating a set of 4 on-contour raised beds on a steep bank. I used tyre sidewalls for the walls. Each bed is retained by two overlapping tyres held in place with metal pegs (made from a set of old tent poles that were hanging around). I think they should be long-lasting and virtually unbreakable. Of course, you do have to cut across the tyres with a metal-cutting blade. I only used them on the downhill side of the bed.
Here’s a photo: http://www.lesspress.com/twiki/pub/Media/Gallery/raisedbeds.jpg
(The beds are covered with cardboard to prevent light damaging the soil which has been dug for the first and, I hope, last time.)
24 Jun 1:56am
How about recycling wine bottles? I just insert in a roll top down into the soil give a few twists every day for a week and wah lah, a wall that does not leak toxins, as a bit of humor and can be used next year.