The Allotment Book. Andi Clevely

With three vegetable groups and three beds to rotate them in annually, each group will get back to where it started in the fourth year, so this standard system is called a four-year (‘course’ or ‘stage’) rotation. It is not inflexible: you can extend the number of years before a group returns to its original position by adding extra courses; some gardeners give maincrop onions a bed to themselves, grow potatoes as a separate course from other roots, or allow one or more fallow years for green manure crops.

      Nor is the system infallible. Some vegetables, especially winter crops, overlap inconveniently with others. Some pathogens survive in the soil for many years, so you still need to be alert for symptoms of disorders. Opinions differ about whether it is better to isolate crops with common serious disorders – separating potatoes and tomatoes to prevent the spread of blight – or grow them together to keep the problem in one place, where it is more manageable. Experience will determine your own preferred approach.

      SAMPLE ROTATION PLAN

      This example of a rotation plan shows how three different allotment beds are planted up with the three main plant groups of legumes, brassicas and root crops over a four-year period.

      

      LEGUMES Podded crops like garden peas, French beans, runner beans and broad beans.

      ▸Grow the onion family (bulbing onions, leeks, shallots, salad onions and garlic) here, as they like the same soil preparation.

      

      BRASSICAS Cabbages, cauliflowers, Chinese cabbages, oriental greens, Brussels sprouts, calabrese, sprouting broccoli and kale. If brassica diseases are a problem, include turnips and swedes in the brassica group; otherwise treat them as root crops.

      ▸ Interplant fully spaced brassicas with salad and leaf crops such as lettuce, chicory, endive, corn salad, land cress, claytonia and spinach.

      ROOT CROPS Potatoes, carrots, beetroot, radishes, parsnips, swedes, turnips.

      ▸ Salad and leaf crops may also be grown with this group. Add sweetcorn, celery and celeriac.

      

      OTHER PLANT GROUPS Members of the pumpkin family (squashes, courgettes, marrows, outdoor cucumbers and melons), as well as summer-fruiting vegetables like tomatoes, peppers and aubergines, may be grown with any of the above plant groups, wherever there is space.

      BED A

      YEAR 1: LEGUMES

      CROPS TO GROW Podded vegetables and onion family.

      CULTIVATION Dig in plenty of manure or compost. After harvest plant onions to overwinter and overlap with Brassicas in Year 2.

      YEAR 2: BRASSICAS

      CROPS TO GROW Cabbage family interplanted with salads.

      CULTIVATION Add leafmould or more compost, forked in or as a mulch, and lime the soil if it is acid. In autumn mulch with more compost, to raise fertility for Root crops in Year 3.

      YEAR 3: ROOT CROPS

      CROPS TO GROW Root crops, leaf crops and extras like sweetcorn.

      CULTIVATION Add more compost. After harvest sow green manure to dig in before Legumes in Year 4.

      YEAR 4: LEGUMES

      BED B

      YEAR 1: BRASSICAS

      CROPS TO GROW Cabbage family interplanted with salads.

      CULTIVATION Dig in leafmould or compost, and lime the soil if it is acid. In autumn mulch with more compost, to raise fertility for Root crops in Year 2.

      YEAR 2: ROOT CROPS

      CROPS TO GROW Root crops, leaf crops and extras like sweetcorn.

      CULTIVATION Add more compost. After harvest sow green manure to dig in before Legumes in Year 3.

      YEAR 3: LEGUMES

      CROPS TO GROW Podded vegetables and the onion family.

      CULTIVATION Dig in plenty of manure or compost. After harvest plant onions to overwinter and overlap with Brassicas in Year 4.

      YEAR 4: BRASSICAS

      BED C

      YEAR 1: ROOT CROPS

      CROPS TO GROW Grow root crops, leaf crops and extras like sweetcorn.

      CULTIVATION Dig in plenty of compost. After harvest sow green manure to dig in before Legumes in Year 2.

      YEAR 2: LEGUMES

      CROPS TO GROW Podded vegetables and the onion family.

      CULTIVATION Add plenty of manure or compost. After harvest plant onions to overwinter and overlap with Brassicas in Year 3.

      YEAR 3: BRASSICAS

      CROPS TO GROW Cabbage family interplanted with salads.

      CULTIVATION Add leafmould or more compost, forked in or as a mulch, and lime the soil if it is acid. In autumn mulch with more compost, to raise fertility for Root crops in Year 4.

      YEAR 4: ROOT CROPS

      COMPANION PLANTING

      Few plants grow in isolation, and an allotment is as much a community of interactive plants as any natural ecosystem. Plants can influence the welfare of their neighbours for good (symbiosis) or bad (allelopathy): beans do not grow well next to onions, rue suppresses growth and very little thrives under a walnut tree; on the other hand, legumes help root crops to grow well, chives can ward off carrot root flies, and elderberries will encourage soil organisms to decompose organic material.

      Crop rotation is one obvious form of companion planting, grouping plants with similar needs together. Another example is growing flowers attractive to pollinators or pest predators close to a vulnerable crop: poached egg plant (Limnanthes) flowers early and attracts hoverflies that can control aphids on broad beans, or you could grow a sacrificial alternative host like nasturtiums to lure aphids away from the beans.

      It is worth experimenting with various different combinations, and observing the results, which can vary from one season or variety to the next. Marigolds (Tagetes), for example, help prevent carrot root fly, and in the greenhouse they are used to discourage whitefly, but you need to choose a strong-smelling variety. Other combinations to explore might include planting tomatoes near asparagus, whose roots exude a substance toxic to tomato eelworms, while French beans interplanted among the brassicas can deter some cabbage root and leaf pests.

      choosing the bed system

      The benefits Dividing your growing area into separate beds is the simplest way to organize crop rotation on the ground (see pages 32–5). It makes the routine of tending the whole plot more manageable than when crops are arranged in long rows right across the allotment. The beds are attractive, which is also psychologically satisfying because they are easy to maintain and keep tidy. They also maximize yields because plants can be grown at closer spacings than when access is needed between rows. They are particularly appropriate