Advice
RHS Help & Advice
Crop rotation
The
principle of crop rotation is to grow specific groups of vegetables
on a different piece of land each year. Groups are moved around
in sequence, so they don’t return to the same spot for
at least three years.
Benefits
Pest and disease control: Soil pests and diseases tend to attack specific plant families, so by rotating crops the pests' life-cycles are broken and build-up is reduced.
Weed control: Some crops (e.g. potatoes and squashes) can suppress weeds, minimising problems for following crops.
Soil fertility: Different crops have different soil requirements and benefits. Changing crops from year to year minimises deficiencies and allows the soil to replenish.
Soil structure: Alternating between deep-rooted and fibrous-rooted crops improves soil structure.
Planning
Divide the vegetable plot into equal sections of four or more. Decide which crops to grow. Then group them, firstly following plant family (linked to pests and diseases), then soil requirements and soil benefits. To rotate the beds as described below move each bed back one space so that legumes moves into the brassica bay and brassica moves to umbellifers for example:
Year one: as
below
Year two: legumes,
onions, potato family, umbellifers, brassicas
Year three:
onions, potato family, umbellifers, brassicas, legumes
Year four: potato
family, umbellifers, brassicas, legumes, onions
Year five: umbellifers,
brassicas, legumes, onions, potato family
| Family |
Examples |
Soil requirements |
Soil benefits |
| Brassicas |
Cabbage, cauliflower, radish, swede |
Leafy crops need nitrogen-rich soil; may need liming |
|
| Legumes |
Pea, bean (broad, French and runner) |
Well-drained but moisture-retentive; not nitrogen-rich |
Fix atmospheric nitrogen in roots for future crops |
| Onions |
Onion, garlic, shallot, leek |
High organic matter; may need liming |
|
| Potato family |
Potato, tomato |
High organic matter and nitrogen (potato); no lime |
Suppress weeds, break up soil structure |
| Umbellifers |
Carrot, parsnip, parsley, celery, Florence fennel |
Root crops need stone-free soil; not freshly manured; fine tilth |
Root crops break up soil structure |
Some plants have so few soil-dwelling pests or disease that they can be fitted in anywhere in the rotation:
- aubergines
- chicory
- courgettes
- cucumbers
- endive
- fennel
- French beans
- lettuces
- marrows
- peppers
- pumpkins
- runner beans
- squashes
- sweet corn
Rotation design service
The Wisley Advisory Service can provide RHS members with a rotation plan to suit their plots; post or e-mail details of plot size, crops to be grown and numbers of plants required.
Further information
Organic Gardening - RHS Conservation and Environment Leaflet
Garden Organic (previously the Henry Doubleday Research Association) for organic methods of growing vegetables.
References
RHS books Growing Vegetables and Organic Gardening are useful references for successful vegetable growing. E-mail the mail order department at RHS Garden Wisley.