Crop Rotation

Growing the same crop year after year in the same ground leads to a build up of pests and pathogens and an exhaustion of the soil. Eventually crops will fail. Crop rotation aims to prevent this by sowing groups of crops in different beds each season so that each bed has a rest from one group for at least one or two years. There are several practices for grouping leading to rotation periods from three to more then seven years. The two most common, and simple rotations are:

• Three year rotation. This can work in the same way as the four x four method described below, but without the potato. In smaller gardens a three x three practice can be followed and you could always grow potatoes in bags too.
• Four year rotation. The method described below works well in the kitchen garden with each group assisting the next and being assisted by the previous.

Plant Grouping

The grouping of plants should be done to reflect their common growing needs, particularly soil fertility. This also helps simplify bed preparation for manuring and liming.

• Grouping by vegetable family. Given the number of families, this would lead to several or many beds in rotation. The method works well for nurseries and market gardens where large volumes of single species are regularly grown.
• Grouping by edible parts (strict). These groups are defined by the edible part of the plant and provides a simple means to identify which group a plant should be planted with. However, over generalising can mix plants with quite different needs, i.e. chard and spinach have different needs to cabbage and kale but would both be groups as 'Stem and Leaf'. This method may also put plants of the same family in different rotations, potentially leading to pest build up, i.e. potato and tomato are in the same family, Solanaceae, and suffer from the same soil born diseases such as blight.
  • Tuber and root
  • Stem and Leaf
  • Fruit and Pod
• Grouping by edible parts (modified). As above but modified to recognise and avoid the issues highlighted in the strict method and also to provides a grouping of plants with similar soil condition and feeding needs.
  • Potato
  • Root
  • Brassica
  • Other

In the UK climate, tomatoes are often best grown under cover. Although 2018 was a bumper year for outdoor grown it may or may not be exceptional, so, this modified version assumes tomatoes are greenhouse grown, thus avoiding the tomato-potato following. Treating the large Brassica family as a group on it's own covers most stem and leaf edibles, and more importantly contains all vegetables that need an alkaline soil. All other stem and leaf not in the brassica family, such as spinach and chard, are in the catch all group as they share the same soil and feed requirements as the Fruits and Pods.

Separating potatoes from the roots has other benefits. Potatoes take up a lot of plot space, creating a lot of shade and are disruptive at harvest, so making it unsuitable to sow between rows for follow on crops. They are however excellent for breaking up the ground (a bonus in the no dig garden) creating a lighter soil for the following Root group to easily put down fine straight roots.