My New No-Dig Garden Bed
I have just finished building up our new 21 metre square no-dig garden bed:
What is a No-Dig Bed?
No-dig beds are raised garden beds – either free-standing or contained in some way – built up by layering essentially straw, manure and compost. These layers compost over time and provide a fertile, free draining soil, ideal for vegies and other plants. The concept is attributed to Australian gardener Ether Deans, who wrote this book:
It’s an interesting book. If you’ve read it, you’ll know what I mean. Here is some further reading:
- Angelo at Deep Green Permaculture has a great, detailed article on no-dig gardening here.
- And here is a Gardening Australia article.
- And Sustainable Gardening Australia has a good piece here.
Why Build a No-Dig Bed?
A few good reasons:
- Unsuitable soil: heavy clay soil/poor drainage, no soil (no top soil due to excavation, or concrete surface) or nutritionally deficient (sandy) soil.
- Reduced mobility: you have trouble bending over for often or for long periods (although there is bending involved in setting them up so get some help!).
- Maintaining soil life: you don’t want to dig down into your soil and disrupt all the organisms living there. By building up layers of humus and compost etc you replicate a less disruptive and more efficient process of soil production.
I’ve bee using no-dig gardens for vegetables for three years and I’ve found them excellent. I’ve grown summer and winter vegies with great results and find the worms move in pretty quickly. Here is my current crop of garlic growing very well in one year-old no-dig beds:
My observation is also that with straw composting down, the water holding capacity is really great, even in hot weather (although you do need to mulch in some way of course, whether by using straw or a living mulch). And finally, I live in an area with heavy clay soil and my new garden, which we bought 18 months ago, had not much in the way of established garden beds and there was no way I was double-digging tens of metres of garden beds in heavy clay. And this is a good thing, because I’ve noticed that the beds I started this past autumn have loads and loads of worms in there now, so there is some evidence of their benefit to the soil and the organisms living there. Also, when I have dug down, I’ve dug up a few frogs and so far have been lucky not to spear them in half. I now use this method to prepare all garden beds, including most recently for all my newly planted fruit trees.
If you research online, you’ll see there are many recipes for no-dig beds. At the very least you will need:
- Straw: carbon-rich and provides height and drainage, but breaks down/composts over time providing nutrients and soil conditioning.
- Manure: nitrogen rich, which helps the carbon-rich straw compost.
- Compost: a soil conditioner and adds balanced nutrients to the mixture.
Depending on your site, budget, and views, you may also need:
- Lime: to help kill off weeds and grass.
- Cardboard: to help smother weeds and grass.
- Lucerne: nitrogen-rich, to help cardboard (carbon-rich) break down.
- Blood and bone: extra help for layers of straw to break down and fertilise bed.
- Wheelbarrow for carting bulk materials.
- A wide, light-weight shovel – you’ll need it if you’re doing large areas with bulk compost and manure.
- A rake can help to even out the compost and manure layers.
- A hose (you water the dry layers in to kick-start the composting process).
I recommend you get your materials, at least compost and manure, in bulk from a gardening supply centre. It’s much cheaper than bagged products. Although if you are after certified organic manure and compost, you will be lucky to find those in bulk.
- Compost and Manure.
Cubic metres: length (m) x width (m) x height (m) = cubic metre. Example using my garden bed approx: L7m x W3m x H.5m = 10.5 m cubed. But, you subtract from this whatever you are going to use in pea straw, as you you add a lot of the height with pea straw
- Pea Straw and Lucerne:
Lucerne, if purchased commercially, should tell you what area it will cover at what depth on its packaging. The bales I bought covered 7metres squared at a depth of 5 cm.
Pea straw, judging by my unmathmatical/unscientific method, I would say that 1 regular rectangular bale bought commercially, covers about 18 metres square at a depth of about 10cm.
Having said all that, I didn’t calculate, I just (under)estimated and went back for more. We have access to a trailer so we can afford to do that. Our centre charges $33 for delivery so you might want to calculate ahead of time if you don’t have a trailer.
At my garden centre, costs are as follows:
- Cow manure: 1 cubic metre = $55
- Compost: 1 cubic metre = $62
- Pea straw: 1 rectangular bale = $13.
- Manure: 2.5m cubed = $137
- Compost: 2.5m cubed = $155
- Pea straw: 4 bales = $52
Total cost for 21 square metres at a depth of 40cm: $344
Sounds expensive but the outlay is a lot cheaper than buying bagged products. Also remember that this will be your soil for a long time to come. You simply top it up each year as you would any garden bed. If the level drops a lot or too low, layer another full layer of straw, manure and compost a few weeks before you replant. I haven’t yet had to do this for my vegies. Although you may need to – here is a shot of my strawberry bed which has dropped a lot in the 18 months since I prepared it (not a problem for strawberries though which don’t have particularly deep roots):
However, if you have the luxury of great soil in your garden already, use it! I’m building up because I have heavy clay – not a friend of the vegetable grower – and what soil there is, is not deep as my block is already excavated.
Edging Your Bed
You can build your free-standing, within a corrugated or wooden sleeper bed (see my shot above of strawberry patch), or within an edging of straw bales. If you do the latter, the bales will break down over time. Here is a shot of one such bed at my place:
But this is not a bad thing – it means you have a beautiful material to mulch your beds with or add to your compost. In my case I just have to pull out errant cooch weed suckers but that’s quite easy to do from the loose straw.
Building Your Bed
It’s pretty simple – you just layer the materials. Some sites are specific about thickness of layers. I just put thick layers of straw, and slightly thinner layers of compost and manure. Say 15-20cm of straw, and 10cm each of manure and compost.
Remember to bend with your knees and be kind to your back as there’s lots of bending and using shovels.
Here’s a diagram from Esther Dean’s book about layering your no-dig bed:
- If building over grass and weeds, sprinkle lime, water in, and top with wet/soaked cardboard. Here is an area of my bed that I built up directly over grass and weeds so I started with cardboard:
- Lay down layer of lucerne (preferable to pea straw over the cardboard as lucerne has higher ration of nitrogen and will help the cardboard break down more quickly).
- Layer cow manure, compost, pea straw, handful of blood and bone, and water in.
- Repeat until desired height reached.
- Some instructions will direct you to finish with alternating layers of compost and lucerne.
Here are the before, during and after shots of my large no-dig bed:
Planting Up Your No-Dig Bed
For vegetables, you need to either:
- Let your no-dig bed compost for a few weeks before planting OR
- Dig a hole wider than your planting hole, fill it with potting mix, and then plant your seedling or other plants into the potting mix.
For fruit trees, you also need to make sure that the manure and compost is aged. For beds prepared from scratch, I let them compost for at least six weeks. This is the approach I took with a bed for the loquat and feijoas below:
If you’re preparing an existing bed to plant fruit trees, I simply top it up with mixed straw, compost and manure and let it sit for as long as I can before I need to plant – but it doesn’t require as long as a no-dig bed built from scratch, because there is already a body of healthy soil (hopefully) underneath this mixture for the tree’s roots to grow into.
Maintaining Your No-Dig Bed
Simply top up your bed with well composted compost and manure each season as you would for any garden bed, depending on the needs of the vegetables or plants to be planted there. If the level drops dramatically, build up another full layer each of straw, manure then compost.