Debunking The Raised Bed Myth

Debunking The Raised Bed Myth: In Defence Of Traditional Organic Methods.

For some reason it seems to be the convention these days to advise new gardeners to grow their vegetables using raised beds and/or the no dig method. This has become the new orthodoxy. The media is teeming with adverts for raised bed kits and even the soil to fill them. (I wouldn't be surprised if there's one or two in the sidebar).

I was stirred to write this piece after reading a review of the Jon Jeavons book "How To Grow More Vegetables Than You Ever Thought Possible", in which the author advocates the use of the raised bed/no dig system, or as he names it (they always have a name), bio-intensive. The reviewer (the otherwise excellent Rob Hopkins) writes as follows:


"One of the great achievements of the book is how it highlights the absurdity of many gardening practices. On a conventional allotment, the whole thing is dug over, manured, and then rows are marked out, with the plants being planted in rows as the gardener walks up and down between the rows to look after them. Sounds logical in theory, and is has been the unchallenged orthodoxy for many years. But in practice, what is happening is that you are manuring the paths as much as the beds, digging the beds and then compacting the soil in them back down again, leaving space for weeds to grow in ground you have kindly manured for them, and basically creating several rods for your own back.

In the biointensive system, the raised beds are double dug, so as to maximise the depth of root penetration, and from that point forward, compost is only added onto the tops of the beds, which are never walked on. Most plants are started first in modules or in flat trays and then planted out into the beds on the tight spacings. This means that if you plant, say, lettuces, you may need to give a light weeding after a couple of weeks, but beyond that, they grow over and make a canopy, so there is no room for weeds to grow. Brilliant.

The successful application of the biointensive mode requires a lot of compost..."


I started gardening in the eighties, after the "Good Life" boom of the seventies had petered out (to be replaced by the rapaciousness of Thatcherism, but that's another story). Allotment sites were disappearing to development at a rate of knots. I was lucky enough to get a job with the Parks Department and a couple of years later acquired my first allotment. I learnt not so much from books but from watching and learning from the old timers on the site, all of whom had plots bursting with vegetables grown using traditional organic methods. Yes, manure was delivered to the site by the trailer load and dug in at the beginning of the season and yes, they chucked on growmore as well for good measure. (Though personally I've always used blood, fish and bone). After 25 years of putting into practice what I'd learnt I think I'm starting to get the hang of it, and I'm proud to say that each year I too now have a plot bursting with fresh produce.

As one of these "absurd" gardeners I'd like to make the case for these traditional methods. (Actually I like to think of myself as a "traditional organic" rather than a "conventional" or an "absurd" gardener).

To start with, this has been the orthodoxy for many years because, I presume, our ancestors spent hundreds of years figuring it out. I think it's worth paying them some heed. Unlike us urban dwellers they spent their whole lives on the land so it's not unreasonable to think that they knew a thing or two about what they were doing. So...

"On a conventional allotment, the whole thing is dug over, manured..." I think there's a good reason for this. On any garden the soil looks static but as we know it's teeming with life - earthworms, centipedes, right down to the microscopic level with all the bacteria and so on who are busy breaking down that manure or compost and distributing it throughout the soil. All that life is moving around, no doubt some of it from one end of the plot and back again during a season. Now imagine a forest on a hundred acres and all the diversity it contains. But in a forest of only ten or even fifty acres there will likely be less diversity. Now going back to our life in the soil I would like to postulate that THE MORE SPACE IT HAS TO MOVE AROUND IN THE MORE LIFE AND DIVERSITY THERE IS LIKELY TO BE. So it follows that if you divide your plot into narrow raised beds enclosed by boards the less beneficial life you will have in your soil. I'm not a scientist so I can't prove this, it just seems like common sense.

"In the biointensive system, the raised beds...are never walked on." I've worked in gardens with raised beds and unless they are waist high then it's extremely uncomfortable trying to work on them without walking on them, or at least putting your boot on them from time to time.

"Most plants are started first in modules or in flat trays and then planted out into the beds..." Nothing new there then.

"...on the tight spacings.This means that if you plant, say, lettuces, you may need to give a light weeding after a couple of weeks, but beyond that, they grow over and make a canopy, so there is no room for weeds to grow. Brilliant." Isn't it just. Nothing new there either. I'm starting to notice a pattern here. Except for the raised bed bit this is just the same as the traditional system.

"The successful application of the biointensive mode requires a lot of compost." As in the traditional method, where it's dug in. But this is different. Here you only dig once and then in the following years you add the compost from above. Whoopee! No more digging! Unfortunatly, leaving compost on top of the soil means you lose a lot of its goodness through oxidisation. (I too use compost as a mulch once plants are growing away nicely, if I can spare it, but this is in addition to, not a substitute for, incorparating it into the soil at the start of the season).

"Companion planting" Can't argue with that, but again it's hardly a new idea.

"...the plants being planted in rows..." This is just a matter of practicality. If I had an endless supply of time on my hands I might plant in wavy rows, it might even be more aesthetically pleasing to the eye, but it'd be a bugger to plan and work round.

"...as the gardener walks up and down between the rows to look after them...compacting the soil..." Wrong. When I've not long dug over my plot and I'm sowing in the spring when the soil is still damp I work off planks so as not to compact the soil. I then don't need to walk on it again (and wow betide anyone who does) until a few weeks later when I need to start weeding. By then the top of the soil has likely settled and dried out and isn't going to be compacted because I walk backwards with my dutch hoe loosening it up. And all that life is still going on its merry way beneath my feet. I end up with blocks of plants around four feet wide, for example if I've got three rows of french beans I can reach over with my hoe to weed between the rows until the gaps has closed up and shaded out most of the weeds.

The reviewer doesn't mention watering. Raising the soil a foot above the water table inevetably means lots of watering, especially around the edges near the boards where the soil will quickly dry out. Using traditional methods once I've watered in my plants or my seed drill I NEVER NEED TO WATER, except in extreme drought conditions. One of the prime reasons for digging in manure or compost is that it holds the moisture in the soil.

Pest control: Go outside and pick up a plank that's been lying on the ground. Clinging to the underneath will be lots of slugs and snails. Now see what you have where you've got planks of wood in contact with damp soil around a raised bed.

In the traditional system I rely on hedgehogs to take care of my slug and snail problem. Around two sides of my plot is a two metre strip of blackberries where they live and I often see them trolling their way around the place of a nighttime. Now, have you ever seen a hedgehog climb up a one foot plank onto a raised bed? I think not.

Another argument often given for the raised bed system is that they warm up quicker in the spring. I'm yet to be convinced that moving the soil a foot nearer the sun will achieve this. And even if it were true it hardly outweighs the disadvantages already outlined. On top of that you've got to spend hours constructing the darn things in the first place. Probably you'll want to use recycled timber but that will rot in a couple of years of being next to damp soil. So then you'll go out and buy some pressure-treated timber or scaffolding planks and try not to worry too much about how that'll affect your carbon footprint, or what damage those heavy metals from the treatment are doing leeching into your soil. Then you're going to have to move around vast amounts of soil to fill them up. You'll have to make paths between your beds which means slabs - a lot of slabs - or imported bark with dozens of metres of weed control fabric underneath it, or hours with the strimmer. Again, I'm not a scientist but it would be interesting if someone were to do a study of the time/reward ratio of all this compared to two or three days digging once a year.

For me raised bed gardening just seems like an unnecessary complication. What's wrong with "There's the ground - go work it"? But that would be absurd. Wouldn't it?

Simon 14.3.09
This article is open source, not copyrighted, feel free to spread it around. Hopefully it might be catching. And when you're done, don't forget to compost it.