The No-Dig Allotment

It is accepted wisdom that to grow vegetables successfully you need to dig it over every winter.  THIS IS NOT TRUE! 

Many traditional gardeners will tell you that digging is the foundation of growing successful vegetables, and 9 out of 10 allotmenteers still seem to follow this approach. And it is of course fine if you enjoy digging. But if, like me, you have a bad back, or simply prefer not to dig, there is an alternative.

How I discovered the no-dig method.  I spent several months in hospital a few years ago and one legacy of that is a chronically weak back. When I retired, and a few months later got my first allotment, it was overgrown and neglected, as they usually are.  I started off trying to convert it the traditional way, by digging it over systematically.  It was agony! I only managed a few feet each visit  and  thought I would never get the allotment into production. That first year, my wife and I had cleared 2 beds by many hours of digging, with me turning the soil over (with a straight back), and her on hands and knees removing weeds. and had just about decided that it was unsustainable.

But then I started reading around the subject and found some publications by Bob Flowerdew and Charles Dowding, that suggested an easier way. So without any great confidence that it would work, I covered an area with weed-suppressing mulch, cut holes and used a bulb planter to plant spuds, this without otherwise preparing the soil at all. I was surprised to find that when I came to harvest, there was a healthy crop of spuds under the mulch and most of the weeds had vanished.

So I converted the rest of that allotment without digging, and when I was offered a different one nearer to home a couple of years later, I converted that without any digging as well (much to the bemusement of my neighbours.)

I will talk later about how to convert a neglected allotment.

Arguments against no-dig

Let us look at some of the arguments against the no-dig approach.

A:         “You need to loosen the soil to aid the passage of roots”

This presupposes that you have soil sufficiently hard that roots cannot penetrate

without help.  Soil can become compacted if it is trodden on, especially when

wet, (or on a farm scale driven over by a heavy vehicle.)

The solution on the allotment is not to tread on the soil and risk

compaction.  Traditional vegetable growing in rows results in the paths between the rows being walked upon many times through the growing season, and these temporary paths become compacted.

However the fixed bed system eliminates that. Fixed beds mean fixed paths. If you only walk on the paths and do all cultivation from there, then the soil is never trodden on and remains loose.

And in undisturbed soil which has not had applications of artificial fertilizers, there soon develops a healthy worm population and it is these worms that ensure the soil remains loose as they pull compost and manure into the soil

B:         “You need to dig to incorporate manure or compost._

Well actually you don’t.   The conventional practice has us digging a trench, putting manure at the bottom, and inverting the soil from the next trench on top, and repeating.  “It’s down where the roots need it`’ we are told. `but how long does it take for the roots to get down far enough to reach the manure`? With shallow rooting crops maybe never.

C:         “Turning over the soil helps to bury weeds”.

The answer here is to avoid having weeds in the first place.  Perennial weeds, which are the ones turned over by winted digging, should be removed by hand during the dormant season, and certainly before they have seeded.  Then there is nothing to turn over. Yes  this is harder work. But an initial investnebt which will save time later on

So now let us look at a couple of counter-arguments in favour of the no-dig approach:

There are better things to do in winter!  It may sound flippant, but it is true.  I rarely go to the allotment in winter – I just don’t like cold weather – except for the harvesting of winter vegetables.  While my neighbours dig over their plots, I take a long holiday in a warm country.

It preserves the natural established soil structure. 

In healthy soil there will exist a network of tunnels created by worms which aids the passage of roots. . Digging destroys this natural structure. There is also a network of micro-fungal filaments which help nutrients  get to where they are needed. Digging destroys these too.

It imitates nature

The no-dig approach imitates nature – leaves, manure, and other organic debris settle onto the surface. From there the worms and other soil organisms pull the organic matter into the soil and assist it in decomposing.  It is in this medium that plants naturally take root and thrive.

It is interesting that a few months after covering soil with a layer of compost it has vanished, maybe a bit longer with the nuggets of horse manure, but eventually.  The soil surface is visible again, though the texture has changed slightly with the addition of worm casts.

Charles Dowding’s trials have shown that 2 beds  side by side, one in which the compost is dug in, and one where it is laid on top,  the overall harvest is approximately equal, but the no dig bed is ahead for several months, the dug bed only catching up in the autumn.  There are fewer weeds and slightly less pest damage on the undug bed.

So why to people still dig? 

a)    Tradition       Gardeners tend to be conservative and allotmenteers a more conservative subset of those. (On a few occasions I have asked why gardeners do something in a particular way and have been told, “That’s how my grandfather showed me when I was a nipper” or “Some old chap showed me how to do it years back”) 

One suggestion is that techniques were learned in the village from those who worked at “The Big House”, with a kitchen garden, rarely questioned.  And in the winter digging was simply something to keep the otherwise relatively idle workforce occupied. These practices have since been passed down through the generations.

b)   Regularity     An allotment is a hobby which has the regularity of a job for some people – digging gives them something to do in the winter which is an otherwise quiet time of year.

c)    To loosen soil            We have looked at this, but it bears repetition If you don’t tread on the soil where you grow your crops, the soil will not be compacted and will not need loosening.

So how does no-dig work?

a)    Mark out fixed beds 4’6” to 5’ wide, Your reach will determine how wide the bed can be; you need to be able to reach to the middle of the bed comfortably from the path. The length should not be much more than about 12’, or you will be tempted to cut across. Much longer and you should think about dividing it into 2.

b)   Separate the beds with 12” – 18” paths

As for the width of paths, I made mine slightly too small for my kneeler and regret it –I suggest you buy your kneeler first, then build the paths so that it fits. (The argument that you need to have the paths wide enough for a wheelbarrow does not apply for the paths between beds on an allotment, but it useful if you have a path down the centre of the allotment.) 

Do all gardening from the paths and use a board if  you need to tread on the soil. (I find it handy to kneel on a board when sowing seeds for example.) CD suggests that once a bed has been converted to no dig for a year or 2 the soil structure is robust enough to generally withstand some treading without harm. I don’t risk it.

c)    Remove as many perennial weeds as possible  before starting!

d)   Mulch with compost or manure annually  Feed the soil not the plants! Ideally spread a 1-2” layer of compost or manure on beds every time they are empty.  Once the allotment is established, don’t apply fertilizer.

e)    Covering Paths – grass looks nice but needs mowing. Bare soil is possible, but can be muddy and weeds may root.  I use inverted carpet. I did use to sprinkle sawdust (from preparing my firewood for the woodburner) but found that in a year or 2 it decomposed to compost and provided a growing medium for weeds, so now I don’t. Spreading woodchip over the carpets is good – branches too thick to compost and too thin for the woodburner can be chipped when brown, they will take much longer to decompose than sawdust.

f)     Edging paths I am still uncertain what is best.  If you don’t edge your beds and continually add compost every year, the level of soil will rise slightly and some will inevitable spill onto paths.  On the other hand planks do provide hiding places for pests such as slugs snails, woodlice. Probably not edging has the edge.

g)   Sourcing compost and manure

·      Have some compost bins at the allotment, I think 3 is best – one using, one stewing and one making.  I don’t turn. Turning speeds the process up, but the overall amount of compost is the same, and turning, like digging, is work. 

·      Have compost bins at home. I don’t have a lawn but find that kitchen waste, with a little domestic garden waste and some newspaper works fine.  Urine helps.  Some neighbours might be happy to give you their lawn mowings instead of paying for a brown bin.

·      Import manure   Get cow manure from farms – often you can collect for free or have it delivered for a fee. If you live in town then horse manure from stables – a waste product they are only too keen to get rid of.  Unfortunately my wife is still too car proud to allow me to fetch bags of fresh manure in it so I have to pay. A neighbour at the allotment is happy to collect a pick-up full from stables for £20, about 50 bags, so I use him.

·      Soil conditioner from green waste. In Norfolk a few years ago you could collect this for free if you could show an allotment contract. Then it went up to £10 a ton – my Renault Clio’s boot wasn’t big enough for more that 200kg – when I finally got a vehicle with more muscle I found they had stopped providing it loose altogether and one had to buy bags. Worth looking into where you live though.

·      Keep hens!! Not only do you get the eggs, but you can throw absolutely everything green that comes out of the allotment at their feet, and they will scratch and pack and pee and poo and turn it into wonderful compost for you.  In the winters when there wasn’t much green coming, I found some streets where there were large deciduous trees and raked up the leaves. Then I noticed that the residents were collecting the leaves themselves in bags for the council to collect, so I took them instead and gave the hens a bag or 2 a week.  Leaves by them selves make leaf mold, which is a good soil conditioner but doesn’t have much in the way of nutrients. But when mixed with the manure from the hens, it turns it ito a much richer compost.

Here are some observations I have after using the no-dig approach for several years.

(a)          No dig and Yield. I believe that the overall yield is about the same with fixed bed as with traditional gardening, if anything slightly higher – yes you lose about 20% because of the paths, but you gain because you can plant much closer in beds than you can in rows.

(b)          No-dig and Potatoes! Hitherto this has been my biggest problem with no-dig!  Unfortunately potatoes grow better in soil that has been loosened. So this is where my no-dig practice has fallen down.  Until this year I have put manure on the top in the autumn, but unfortunately my worms are not well-trained enough and it has only been partially absorbed by planting time in spring.  So I lightly forked it in and planted using a bulb planter 18” apart in the beds. I grow on the flat with only slight earthing-up. I have found that the deeper I plant the larger is my crop, but the harder it is to harvest.

However, and this is the point,  I have found that if I don’t thoroughly dig the bed over afterwards I have loads of rogue potatoes growing through the following season’s onion crop. We usually collect an additional basketful during this digging over.  So my allotment has hitherto only been only no dig for the 4 years between potato harvests. 

Incidentally although I do get a few more green spuds using this method, I also break another rule and keep back some of my own potato seeds  for planting the following year. Green potatoes may not be safe to eat (at least the green part isn’t) but they are perfectly good for seeds. I find I can get away with 3 years before needing to buy in fresh seed potatoes.

It is possible to sacrifice yield by having 2 traditional rows in a no dig bed with a board down the middle, earthing up as with traditional growing

This year I have approached my potato beds differently. I am growing more shallowly, placing them under a 6” layer of compost without any forking in, and without using the bulb-planter. I suspect yields will be lower but it is worth a try. I will rummage around in the soil/compost by hand after harvest and see if I can find the missed spuds that way, thereby avoiding the dig-over. We shall see.

(c)           No-dig and Brassicas.  We are told to tread down the soil in which we grow brassicas. What I do is tread down the, say, 6” all  around the plant only. Then when I use a fork to gently lever out the stalk afterwards, this soil is loosened again.

(d)          No-dig and Alliums

We are told that the onion tribe grow best in soil which has been manured for the previous crop. I haven’t tried growing onions in freshly manured soil. What I have done is allocated the potatoes a double ration of manure, and follow then with the onion family  without any more manure.  However this does mean that there is more weeding of annuals in this bed than I would like.

(e)          No-dig and Crop Rotation

One simple fact for someone who is bad at record-keeping like me – using fixed beds makes it it is easier to keep track of what was where last year and where it should go next year

(f)           No-dig and Weeding

As many perennial weeds as possible should be removed at the outset. Any that you miss should be easier to pull up later from the loosened soil in the beds.  Annual weeds should be removed as soon as they are visible. One interesting point is that no-dig means not bringing up long-buried weed seeds from below to germinate. Once the first year’s crop of weeds has been removed, the remaining seeds stay under the soil.

(g)          No-dig and Mulching   I strongly recommend that you mulch your soil whenever it is empty. Ideally the mulch will be compost or manure, but anything – cardboard, black plastic, will prevent weeds from germinating.   I mulch my beds with horse manure, and the number of weeds that germinate is miniscule compared with any unmulched beds. However, if you make your own compost, be sure to remove any seedheads before adding.

(h)          No-dig and Pests

·      Slugs don’t like the rough surface of undug compost.

·      I use a barrier method wherever possible:  nets over brassicas, mesh over carrots, etc

·      I soak, sprout and pot on peas and only plant them out when the seeds are old enough not to interest mice, and the pea sprouts are tall enough not to interest birds. (Swilling in paraffin doesn’t work at my allotment, the mice have been there a long time and are wise to all those tricks – learn them and grandmother mouse’s knee!)

·      Tolerate some loss to pests without panicking – the birds tokk some of my strawberries this year, but there were enough to go around. And if you are careful when you shell peas, you can discard any that are inhabited by the pea moth.

·      I do find more tunnels under the compost than before – presumably mice.

(i)           No dig and disease

·      No walking on soil means less chance of transferring disease on shoes, eg club root. My neighbours in all directions have club-root on their plots. However I’m not very hospitable and don’t invite neighbours into my allotment. This way they don’t bring their club root in.  And as I don't tread on the soil anyway, if I do pick it up on my boots from somewhere, I am not transferring it to the beds.

·      Avoid disease by growing plants in their correct season, so don’t believe the exaggerated claims on some seed packets. I don’t grow, for example, peas in autumn or potatoes for Xmas. It is possible, but the peas inevitably get mildew and the spuds inevitably blight.

·      Tolerate some disease without panicking – eg scab on spuds or mildew on squashes. But serious disease, eg potato blight, needs to be dealt with promptly.

·      Be aware of the possibility of some disease being imported with manure eg white rot on onions

·      Use disease resistant varieties – I grow Sarpo Mira or Sarpo Axona maincrop potatoes – it is an unexceptional floury spud, difficult to get going in the spring, and sometimes weirdly shaped, but it simply shrugs off blight. (Incidentally the slow to sprout tendency means it lasts well into the spring in storage)

·      Practice good garden hygiene. Eg I never have tomato blight in my greenhouse whereas my neighbours frequently do. I subscribe to “blightwatch” they email or text if there are blight conditions in my area. At those times  I wash my hands on the way into the allotment and do the greenhouse business first before touching any other plants.  In this way I avoid bringing spores in on my hands. In those periods I keep my g/h door closed even if it is hot. And I water into pots rather than into the air and onto leaves, which has the risk of spores splashing up onto lower leaves.

   (j)          No dig and watering

·      Close spacing sometimes creates a canopy which means less evaporation

·      High organic matter content means more water is retained in the soil

·      Not watering routinely encourages plants to deep root rather than surface root . I rarely water once plants are established.

(k)             No dig and green manure

·      I don’t do it – it involves digging it in afterwards

·      Anyway I rarely have beds empty for long enough

·      Green manure is used as a way of retaining nutrients . However we can stop any loss of nutrients by mulching instead

  (l)         Exceptions to No-Dig

We must acknowledge that sometimes even no-diggers do need to reach for the fork or spade – when lifting an 18” parsnip for example, or removing old brassica stalks. And there is the problem of potatoes I mentioned above.

So what we are discussing is no routine digging.