Allotment Growing

Crop Rotation - Plant Families or Groups

When planning your crop rotation you need to know what family the various plants belong to. Plants within the same group tend to have the same requirements and suffer from the same pests and problems.

For example, clubroot affects brassicas, the cabbage family, but did you know swedes are brassicas? They look more like a root crop than a cabbage!

Blight is mainly thought of as a problem with potatoes, yet it affects tomatoes just as badly, once again members of the same family.

The list below should help you identify what crops need to go together in the crop rotation.

• Cruciferae - the cabbage tribe, formerly known as Brassicaceae from which we get Brassica. This is one of the most important crop groups in a rotation as they are generally lime loving. Because of the requirement for a high pH level, they anchor one end of the crop rotation cycle.
  The group includes:
  Cabbages, Cauliflowers, Kale, Broccolis and Calabrese, Swedes, Turnips, Radishes, Landcress, Mustard
• Solanaceae - the potato family, which also includes tomatoes and aubergines. The potatoes form the anchor at the other end of a rotation as they need a fairly high level of nitrogen and prefer a slightly acid soil with a pH around 5.5. Usually manure is added to the plot the autumn before planting the potatoes.
• Leguminosae - the bean family of legumes. Anything with 'bean' in the name, runner, French, broad, field and peas which are one of the oldest food crops grown by man. These share a wonderful ability to fix nitrogen from the air and so provide at least a good proportion of their fertiliser requirements.
• Alliums - the onion family. Allium comes from the Latin for garlic and includes shallots and leeks.
• Cucurbitaceae - the cucurbit family includes cucumbers, marrows, courgettes and pumpkins as well as cucumbers.
• Umbelliferae - this includes carrots, parsnips, Hamburg and ordinary parsley, celery and celeriac.

Species not listed above, like sweetcorn, can be considered out of the family groups and safely intermixed with them. Salsify and scorzonera are members of the Compositae family but best considered as Umbelliferae along with the parsnips.

More on Crop Rotation

• Crop Rotation
• Plant Families & Groups
• Three Part Crop Rotation
• Four Year Crop Rotation
• Five Year Crop Rotation