In a natural ecosystem, disturbed or bare soil is very rare. An undisturbed soil, covered with plant material, either living or dead, is protected from erosion and free to develop its natural fertility. Moving and exposing the soil disrupts the biological processes of fertility and leads to the loss of precious organic matter.
So why do we dig our gardens? The main reason is to relieve compaction, and the main cause of compaction is treading on the soil. If a garden is laid out on a bed system, gardening without digging becomes a possibility. A bed system consists of beds alternating with paths, with the beds sufficiently narrow that every part of them can be reached from a path. The gardener never needs to tread on the growing area, so there is no compaction.
Doing away with digging saves a lot of work. What’s more, although quite a large proportion of the garden is composed of paths, the overall yield is usually higher than in a traditional vegetable plot. In part this is because the vegetables can be placed equidistant at their ideal spacing in both dimensions. Without a bed system they must be planted in rows, to allow space for the gardener to walk between them, so they’re too close to each other in one dimension and too far apart in the other.
No-dig is not a dogma. Sometimes it may be worthwhile to dig, perhaps to remove perennial weeds or to mix in compost in a raw soil. But these occasions should be rare in most gardens.
In nature, mature ecosystems are composed almost entirely of perennial plants, that is plants which live for many years, in contrast to most of our vegetables which are annuals and only live for one year. There are advantages for us in imitating this aspect of natural ecosystems.
Anyone who has grown both fruit and vegetables will know how much less work it takes to grow the fruit, which is perennial, compared to the vegetables, which need to be raised from seed each year. But there are a number of perennial vegetables, and other vegetables, that can maintain themselves in the garden by self-seeding.
Most perennials are more resistant to pests and diseases than annuals, and once they’re established they’re too big to be troubled by slugs. Since they keep the ground covered for all the growing season, weeds hardly get a look-in.
One of the most useful perennial vegetables is Daubenton’s perennial kale. Easily grown from cuttings, it can give you abundant greens all year round with hardly any attention. Sea beet, the perennial form of leaf beet, gives its yield of spinach leaves mainly in the spring, when there are few annuals available for picking. Leaf beet and its sister Swiss chard are among the most successful self-seeders, while rocket, land cress and lamb’s lettuce will self-seed readily to give salad greens. There’s a wide range of perennial onions, including Welsh and tree onions and wild garlic.
Diversity is one of the most familiar characteristics of natural ecosystems. Organic gardeners know the value of it, both as the key to reducing pest and disease problems, and in making more complete use of the soil nutrients, as each crop has slightly different needs. They achieve diversity mainly by means of crop rotation, which gives diversity through time. In permaculture we go a step further by working with simultaneous diversity too.
Growing a mix of vegetables in one bed usually takes more care and attention than growing a single crop, but the rewards can be great. Not only do the different plants use different parts of the nutrient resource, but the fact that they have different shapes, grow at different speeds and at different times of the year means that they can share the resources of space and time as well. So the overall yield is higher for the same resource base.
For example, if short, bushy lettuce is planted between tall, thin garlic neither significantly shades the other, and if the timing’s right the garlic will be harvested before the lettuce has taken up all the space. Squashes and sweet corn have the same relationship in terms of space, though not in time. Cabbage and lettuce are more similar in structure but lettuce is faster growing. If the two are planted alternately, the lettuce can be removed when the cabbage is only half grown, thus making use of the empty ground between the young cabbage plants. In summertime, low-growing salad plants, such as lamb’s lettuce and purslane, can actually benefit from a little shade from taller plants in a mixed bed.
The more complex the mixture the more skill and attention it takes to grow it. If there are many different crops in the bed rather than just two, you need to watch it constantly and keep selectively harvesting and thinning as the plants mature at different rates. But the rewards can be correspondingly greater. Whether to grow garden polycultures or not depends on your priorities. They’re most worthwhile if you have a small garden and want to get the maximum yield out of it. If your priority is simplicity and ease of management, single crops are probably best.
In almost every part of the Earth where growing conditions are good enough, the natural vegetation is a multi-layered forest of trees, shrubs and herbaceous plants. Natural grassland is only found where rainfall is lacking, and it generally produces much less biomass per year than forest.
Yet most of our food-producing systems, whether on farms or in gardens, resemble grassland, inasmuch as they are a single layer of herbaceous plants. Multi-layer systems, such as the forest garden mentioned above, invariably yield more food. Although each layer may yield less than it would if grown alone, the overall yield is higher.
In permaculture we call multi-layer growing ’stacking’. Growing vegetables of different heights, as in some of the examples of polyculture given above, is stacking on a small-scale. In general stacking is a matter of thinking in three dimensions, of seeing a garden as a volume of space rather than just a surface area. So using any vertical space – such as walls, fences, window boxes and balconies – for growing can be seen as a form of stacking.
The availability of light is the main limitation on stacking. Open-grown trees in the middle of a small garden, especially one surrounded by buildings or other trees, will leave little light for the lower layers. So in most small gardens the walls and fences around the edges offer the main opportunity for stacking. Fruit trees, most soft fruits and a few vegetables can be trained up walls and fences, hardly impeding the light that reaches the main body of the garden and taking up very little horizontal space.
Fruit trees can be trained as espaliers, fans or cordons. The yield per square metre of horizontal space is higher than for any other method of fruit tree culture. All the cane fruits, plus red currants and gooseberries, can be wall-trained. The hybrid berries are particularly useful; one of my favourites is the veitchberry (loganberry), which gives its yield in the gap between summer raspberries and blackberries.
The choice of climbing vegetables is rather limited. It includes some varieties of squashes and cucumbers, climbing beans and tall varieties of pea. The fact that these all come from two families makes a climbing rotation hard to design. But other tall plants, such as sweet corn, tomatoes and sunflowers, can be included.
The down side of wall-trained fruit trees is that they need more intensive care than open-grown fruit trees. Where very low maintenance is a priority, open-grown trees may be a better choice. Of course these will eventually cast quite a bit of shade, but in the early years a series of edible crops can be grown beneath them. This mimics the natural succession which takes place as a natural ecosystem regenerates on bare ground: the first colonists are annual plants, followed by herbaceous perennials, followed by shrubs and trees.
At first annual vegetables can be grown between the young trees which will also benefit from the manuring, watering and attention given to the vegetables, without significantly reducing their yield. As the trees grow, the annuals can be replaced with perennial vegetables. Most of these are more tolerant of shade and root competition than are annuals. Also, since they take less effort to grow, any reduction in yield as the trees get bigger may be more acceptable. When the trees are mature they can be under planted with shade-tolerant perennials such as wild garlic.
Alternatively, in a large garden where full-sized standard fruit trees have been planted, soft fruit can be grown between them in the early years. The soft fruit will come to the end of its productive life at about the time when the trees start to bear a reasonable crop.
Mimicking natural succession in this way makes for a garden that is constantly abundant through the years, as the focus of production moves from the lower layers to the upper ones.
More from The Minimalist Gardener:
Reprinted with permission from The Minimalist Gardener (Permanent Publications, 2017), by Patrick Whitefield. The Minimalist Gardener a guide to establishing a sustainable, low-maintenance, permaculture garden for year-round food and with suggestions for both small and large spaces. Whitefield is an early pioneer of permaculture and has written Permaculture in a Nutshell, How to Make a Forest Garden, How to Read the Landscape, and The Earth Care Manual.