My raised bed floweth over (if only)

Ask me what I want for Christmas. Go on. I know it's early yet, and Santa's barely roused from his summer slumber (or so I keep telling my children), but I've already planned it out. I'd like a towering pile of well-rotted manure, a 20kg bag of biochar and as much Rockdust as the reindeer can haul.

When I had an allotment, I took it as a given that the soil covering my modest five-pole plot the guts and structure for the job. Every year it produced fat pumpkins, trugfuls of beans and tall sunflowers, provided I kept the rampant weeds at bay. I knew I was lucky: I just didn't know how lucky (this must be the reason why my home county of Bedfordshire has historically been such a centre for veg growing). When I moved house and gave up that plot for an 80ft-long garden, still in Bedfordshire, but not blessed with quite such a fine tilth. The back section is given over to a shed-cum-greenhouse, two compost bins and two wormeries, a couple of regular beds and two 2mx2m raised beds, each about 50cm tall, built just before my son was born three years ago (see right for them in their unfilled state).

I knew the theory that the soil would need improving, but the reality of placing raised beds on previously unimproved soil has been chastening: it's like the moment as a new parent when, about two weeks in, the novelty of being woken at night fades and you realise what the phrase "sleepless nights" really means.

However much organic material and nutrients I pour into those beds, the level lingers stubbornly a finger's depth from the lip. The soil I've got isn't bad, but there isn't enough of it. In idle moments I picture it brimming gently over the top like a pint of Guinness being poured: that's the kind of deep, humus-rich, moisture-retentive environment I'd love for my hungry fruit and veg. But as fast as I throw in wormcasts, homemade compost, spent compost from containers, mulches of grass cuttings and cardboard, the beds seem to soak them up. A few days of sunny weather and the raised beds are drier than an Amish birthday party. Courgettes and beans struggle: lettuces aren't the puffy quilted jobs I remember from my allotment, and rhubarb stems wilt without warning, even under the cool shade of the nearby plum tree.

The more I grow, the more I realise one thing, long known by everyone from Lawrence Hills to Prince Charles by way of Michelle Obama and Raymond Blanc: it's all about the soil. If you've ever been on one of the many allotment forums and read plot holders merrily promoting Jeyes Fluid for "sterilising" the soil of pests and diseases, you'll know what a long way we've yet to convince all gardeners how important those bacteria and organisms are. Alys Fowler reminded me of this in a recent column: one which received the most feedback I've ever had for her writing for the Guardian: in Heart and Soil she wrote about the healing powers of getting your hands dirty, both mind and body. I've put the book Teaming with Microbes: The Organic Gardener's Guide to the Soil Food Web by Wayne Lewis and Jeff Lowenfels  on my Christmas list so I can learn more.

My raised beds are a work in progress: Alys tells me they will reach a tipping point where the humus levels out. Everything I've tried so far - green manures, mulches of corrugated cardboard and grass clippings, rockdust, biochar, and lashings of wormcasts and homemade compost - are all working, but it'll be a while before I have won. I can't afford - and don't really wish to - repeat the exercise of buying in a bulk bag of peat-free vegetable compost to shortcut the task, and anyway, it probably wouldn't work as well in the long term as my slow but cheap solution. If anyone has any top raised bed-filling tips, please shout. I'll try anything, provided its organic.

I do have one tip for impatient gardeners like me: if you have a wormery, and grow potatoes in containers or sacks, here's something to save you time and money. If you're anything like me, the bottom tray in your wormery may look nearly ready for harvesting, but when you delve below the top centimetre or so of wormcasts, you find lots of lumpy bits and a few worms roaming around. When it comes to potato harvesting time, add a square of corrugated cardboard at the bottom of your sack, builder's bucket or pot to absorb any excess water and stop it running out of the holes too quickly, then tip the contents of the wormery tray, worms and all, on top. Add a layer of bought-in peat-free compost, say 10cm-deep, then add the seed potatoes and more compost as usual, earthing up as the plants grow. Shove more cardboard sheets around the sides of the pot if you can, too. By the time you're ready to harvest, the worms will have finished work, the cardboard will be almost gone and the wormery's contents will be completely broken down, barring a few eggshell fragments and the occasional rogue avocado seed. And you'll have well-fed spuds, beautifully clean easy to store.

 

I've been recording my yields from container potatoes for the past few years and since I started this technique, my harvest per container has roughly doubled in weight terms.

Comments

[Veg Plotting]

I've found the topping up slows down after a while. I've also been mulching with grass clippings over the summer which has helped a lot - a top tip gleaned from that garden you recommended for us to visit on Vancouver Island a couple of years ago.

What a great article by Alys - thank you. I found getting my fingers into the soil every day really helped when I was off work with stress a few years ago. This was my response to my Dr's prescription of 'doing something you really like' when he signed me off. What a wise man - it worked perfectly :)

[ChubbOwen]

Hi Jane - sorry have to disagree, there is nothing 'unorganic' about adding topsoil to any raised bed. Sure it costs some money, but in the end it provides the necessary growing conditions immediately and much more convenient than the hit'n'miss frustrating alternatives. In my experience of building raised (mainly for ornamental purposes) it works very well and the cost of very good quality screened soil is modest.
I believe in spending more on the soil than plants, and you'll reap the rewards.
Enjoyed reading your Blog.
Best wishes
Owen

[Jane Perrone]

Owen - I am not saying it's unorganic to add topsoil to a raised bed - in fact it's what I did when the beds were first filled (hence my phrase "repeat the exercise...") but I've found that I'd have needed much, much more to keep the beds filled in the following years.

[Veg Plotting]

Hi Jane - just popped in to add a PS as I've remembered that we had a plot holder up at the allotment who never added organic matter to his non-raised bed soil and relied on chemicals to do the job. His soil was a good one foot below that of the grass paths bordering his plot, whilst everyone else who orders a trailer load of muck every year has their soil above path level. So your observed phenomenon isn't solely reserved for raised beds...