Preparing the Soil: Basic Digging

Preparing the Soil: Basic Digging

Asking someone if they know how to dig seems like a stupid question!. Yet if I asked you to describe the difference between single digging and double digging would you know the answer? If not ……..or you’re a bit hazy then read on.

'Single digging' means digging the soil to one spade’s depth (one ‘spit’); double digging is done to a depth of two spits. The latter was widely practised in private gardens of old, where it was commonly - and more colourfully - called 'bastard trenching’.

If you are unfortunate enough to acquire a garden on a heavy clay soil with poor drainage, then I strongly advise you to  double dig your beds to help improve both the soil fertility and the drainage. Otherwise single digging will do.

The object of single digging is to turn over the top 20-30cm (9-12 in) of soil; the lower levels are then exposed and aerated. At the same time annual weeds, are turned in and buried so that they will provide valuable humus.

Perennial weeds with long tap-roots (like docks and dandelions) will re-emerge if they are buried, so they should be pulled out, left on the path to die, and then placed in the middle of the compost heap. That way every scrap of organic fertilizer that nature provides free is put back into the soil.

Tools for the job

For spring digging you can use either a spade or a fork. If you have a light or sandy soil, or a good loam, a spade will do a better job; but on a very heavy clay, which has lain undisturbed over the winter a fork will make digging easier and the end result will be just as good. So select whichever tool best suits you and your soil.

It is advisable to dig your vegetable plot at least a week or two before you are ready to sow or plant as the soil should have time to settle before you start.


For some people, the thought of digging can be very off-putting. They regard it as a back-breaking work that should be avoided where possible. But this doesn’t have to be the case, if the job is approached in the right frame of mind. So relax, enjoy it and remember its a great way of keeping fit, that it takes you out into the open air and that it is a marvellous muscle-toner. Don’t set yourself im­possible goals and stop before you get exhausted.

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First of all dig out a trench one spit deep and about 3-3-5m (10-12 ft) long at one end of the plot. Don’t make the trench any longer; it is far better for your morale to finish digging a short strip than to half-finish a longer one. Put the soil from the trench into a wheel­barrow and push it to the other end of the plot (where it will be used to fill in the final trench).

Go back to the start of the row and work your way down the second trench, turning the soil over into the first one. Continue in this manner until you have finished the strip.

A word of advice -don’t try to speed the job up by digging great slices out of the soil. It is much easier, and a lot less tiring, to handle chunks no wider than 15cm (6 in) - at least until you have established a relaxed rhythm. Carry on digging down to the end, fill in the last trench, have a rest and then start on the second strip. Do it this way and you will be surprised how quickly the work gets done.

The newly-turned earth is now an uneven surface of gleaming clods of soil. Leave it like this until the day you are ready to sow and plant, to give it a chance to dry out and settle. Then all you need do on a dry day is shuffle and tramp all over it to break down the lumps before raking it to a fine tilth.

Fertilizers and manures

If you want a good, healthy crop, fertilizers are absolutely essential. Assum­ing that none were used in the previous autumn I suggest that a top dressing of general fertilizer, such as Growmore or Fish, blood and bone if you prefer organic, or one of the proprietary, concentrated animal manures should be spread over the soil at 70-145g per sq m (2-4 oz per sq yd.) before you start digging. Digging the plot puts the fertilizer down into the soil where the plant roots will reach and benefit from it in due course.

I also suggest that you keep some of the fertilizer you use and put a little of it, say about 35g per sq m (1 oz per sq yd.) over the whole plot just before you start sowing and planting. This will give the germinating seedlings a boost until their roots reach the main feed below.


Double digging is simply digging the soil two spits deep, that is, to the depth of two spade blades. It should improve the fertility and drainage of a heavy clay soil and is very useful where long-term crops are to be grown or an area is being given over to cultivation for the first time. As in single digging, the soil from each succeeding trench is transferred into the one behind it, until finally, the soil from the first trench goes into the last trench.

Digging and filling

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Double Digging Soil Profile

The first step is to divide the plot into two and mark out the two sections into 60cm (24 in) wide strips. Starting at the end of the plot dig out the first strip to one spade’s depth. The soil should be left next to the adjacent strip in the other half-plot.

Break up the bottom of the trench to the depth of your fork tines and then

1 Double digging the final trench and turning the soil into the one before.

2 Shovelling in the compost and spreading it evenly.

3 Mixing compost in with the broken-up second spit.

4 Filling final trench with soil left over from the first move onto the second strip.

Make sure that each ensuing trench is as near as pos­sible the same width as the one before so that the same quantity of soil is removed and a level surface is maintained. The soil from the second digging goes into the first trench, the bottom of the second trench is broken up and the process goes on until the final trench is filled with the pile of soil

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