Digging is a basic gardening task that can cause a surprising amount of confusion. In fact, it is quite simple - and can sometimes be avoided altogether!
Simple digging
This is lifting a spade of soil, dropping it down, and chopping it up. It can be used to incorporate organic matter, improve tilth (i.e. the structure of the soil surface), or where deeper digging is impractical. It also exposes soil pests to the birds.
Forking
This is the same as simple digging, but with a fork. Forking is easier on stony or heavy clay soils. It aerates the soil, loosens weeds, and breaks up soil clods. It can be a precursor to incorporating organic matter, or to finer cultivation.
Single digging
This is a methodical process efficiently covering a pre-set area to a uniform standard. Mark out a rectangular plot, mentally divide it into two strips, and lift a small trench (30cm/12inwide, and a spade’s depth) from the end of the first strip. Place this soil to one side, leaving the trench empty. Then lift the same amount of soil from the area just behind, and drop it back into the original trench, breaking it up a little. Work methodically down the first strip, and then back up the second one, turning each trench into the space before it. At the end, the final trench is filled with the soil that was left to one side from the first trench.
Double digging
This follows the same methodical pattern as single digging, but after removing each trench, the soil below is forked over before filling back up with soil from just behind. The fertile topsoil and less fertile subsoil can be kept separate, simply taking the opportunity to remove rubble and break subsoil pans, or they can be mixed together. Mixing them will, over time, result in deeper topsoil, especially if organic matter is added regularly.
Surface cultivation
For soils that are not compacted, without problem weeds, and which already have a good organic matter content, shallow cultivation may be enough. Three-pronged cultivators are excellent when dragged through the soil surface, but raking (with a garden rake, not a lawn rake) and hoeing are also useful.
When not to dig
Digging when the soil is very wet can damage its structure. Rotavating it (with a mechanical cultivator) to the same depth each year will create a smeared, impermeable ‘pan’ just below.
The ‘no-dig’ approach
Digging is unnecessary on soils with good initial structure, or on problem soils that have been improved by initial digging. Instead, a deep mulch is laid over the soil in layers of organic matter (perhaps compost, manure and grass clippings), lime, and fertiliser (e.g. pelleted poultry manure or inorganic granules), to a depth of 8-15cm (3-6in). The deeper the mulch, the better it will keep down weeds. Any weeds that do emerge can be hand pulled. The mulch is pushed aside for planting and seed sowing, and can be used to earth up vegetables. Slugs can be a problem in damp mulches.
Maya Albert