Crop rotation, step by step

1. Soil remembers

The diseases and pests of one plant family live in the soil and wait.

1. The same spot for years — Tomatoes in the same spot give a great crop for the first two years. In the third year the plants start wilting in midsummer.
2. Soil-borne diseases and pests — Fusarium, verticillium, nematodes (eelworm) and wireworms build up in the soil year after year. Without a host their numbers fall.
3. Shallow and deep roots — The same plant takes the same nutrients from the same depth. When shallow and deep roots take turns, the soil is exhausted less.
4. A 3–4 year break — A plant of the same family does not go back in the same spot for at least 3, better 4 years. Once clubroot has appeared, the break is 7 years or more.

Why: The same crop in the same place every year means you are laying the table for them every year. Crop rotation is the oldest and cheapest way to protect a vegetable garden: it costs nothing but a pencil and paper.

• Rotation does not cure a disease that has already spread. Clubroot and onion white rot can stay in the soil for more than 10 years.
• Don't carry soil from an infected part of the garden on tools and boots.

2. Vegetable families

Rotation is planned by family, not by crop.

1. Group by family — Before you plan, sort your vegetables by family, not by the name of the crop.
2. Nightshades — Tomato, pepper, aubergine (eggplant) and potato are the same family. They share the same blight and the same wilt diseases.
3. Brassicas — Cabbage, kale, broccoli, cauliflower and kohlrabi, but also radish, mooli and rocket (arugula). Clubroot attacks them all.
4. Cucurbits and legumes — Cucumber, courgette (zucchini) and squash share powdery mildew and viruses. Runner beans, French beans, peas and broad beans fix nitrogen from the air.
5. Umbellifers and alliums — Carrot, parsley and celery get carrot fly. Onion, garlic and leek get onion fly and white rot.

Why: Related plants share the same diseases and pests. Many mistakes happen because people don't know that potatoes and peppers are related, or that a radish is a brassica.

• White mustard used as a green manure is a brassica too.
• The beet family (beetroot, chard, spinach) and the daisy family (lettuce, radicchio) cause few rotation problems.

3. Hungry and light feeders · Locked

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4. The four-plot plan · Locked

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5. Green manures and records · Locked

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6. Companion planting · Locked

Buy the Crop rotation and companion planting module and you get the PDF to download and print, plus lifetime access to this interactive lesson: all 6 chapters, 28 steps.