Crop rotation has been practiced by farmers and gardeners for
generations as a simple and effective precaution against pests and diseases. The basic idea is that if you grow the same type of plant
on the same patch of ground every year, the soil will harbour
pests and diseases from one season to the next. If you move the
crop to another piece of ground, the pests and diseases will lose their host and will die out.
The practical side of this philosophy is the division of the vegetable garden into four
or five areas. The different types of crops – brassicas, beans and so on – are moved from one plot to another so that they return to the same piece of ground only every fourth year.
For four-year crop rotation, the crops are divided into four groups – the fifth bed is used for the permanent plants, which obviously do not move. Look at the list of veget-ables that you wish to grow for the coming year and divide them into their various groups. Allocate planting areas to each. Do the same for the following year, but move all the crops to another plot. If space is limited, a three-year rotation is better than nothing.
As well as having advantages in terms of pests and diseases, there are other reasons for moving crops around. Some crops will tolerate newly manured ground while others cannot. Thus, one plot can be heavily manured when it is dug in the autumn
during the first year and cabbages and related plants can be planted in it in spring. In the following year the plot is simply dug, and the root crops, which do not like the soil too rich, are planted there.
Strict crop rotation is not the easiest of things to maintain. Many gardeners start off with good intentions and manage it for a
few years, but gradually things begin to
slip. Some brassicas that have been left in the ground over winter may block the
space that is required for some other plants, or perhaps a few plants have been slipped in to fill a gap. Leaving plants in the ground until the following year so that you can
collect your own seeds also plays havoc with rotation if you have only a small amount of space. If you find this happening, there is no need to worry.
In a small kitchen garden, crop rotation, although it is admirable in theory, is not that important in practice. One of the main difficulties is the amount of space required to put strict rotation into effect. In agricultural situations the crops are fields apart; even in a large garden, the distances involved can be quite large. In a small garden, however, it is often impossible to get the plots far enough apart for the pests or diseases not to be able to find their host plant. The other problem is that, in practice, four years is not always long enough to kill off all the diseases anyway.
This does not mean that crop rotation is unimportant, however, because it still has some effect. Yet it does mean that you should not lose any sleep if you are not able to follow the sequence to the exact letter. Most gardeners do not grow the same crop on the same ground for two years running in any case – with the exception of plants such
as runner beans – but they do not follow
strict crop rotation.
Four-Year Crop Rotation
Peas, broad (fava) beans, french (green) beans and runner beans.
Cabbages, Brussels sprouts, calabrese (Italian sprouting broccoli), broccoli, kale, radishes, swedes (rutabaga or yellow turnips), turnips and kohl rabi.
Bulb onions, spring onions (scallions), shallots, leeks, garlic, sweet corn (corn), marrows (zuchini), sqaushes, pumkins and lettuce.
Potates, parsnips, beetroot (beets), carrots, salsily, scorzonera, celery, celeriac (celery root) and tomatoes.
Plot 5 (permanent):
Rhubarb, asparagus, perennial herbs, globeartichokes, jerusalem artichokes, seakale.
Three-Year Crop Rotation
Peas, broad (fava) beans, runner beans, bulb onions, leeks, sweet corn (corn), marrows (zuchini), squashes, pumpkins and lettuce.
Potatoes, parsnips, beetroot (beets), carrots, salsily, scorzonera, tomatoes.
Cabbages, brussels sprouts, calabrese (Italian sprouting broccoli), broccoli, kale, swede (rutabage or yellow turnips), turnips, kohl rabi, radishes.
Rhubarb, asparagus, perennial herbs, globe artichokes, jerusalem artichokes, seakale.