Four-year rotation

Rotating legumes, nightshades, cucurbits and root vegetables.

Level: Beginner 4-year cycle, annual planning

Watch the videoRotations et associations au potagerPermaculture, agroécologie, etc.

Introduction

Crop rotation means waiting several years, at least 3 or 4 (Jardiner Autrement, SNHF), before bringing the same botanical family back to the same place. It is a simple and powerful tool to preserve soil fertility, break disease cycles and balance nutrient needs.

Background

Each plant family takes up different elements and hosts its own specific pathogens (blight, clubroot, fusarium…). By rotating the families, you limit the build-up of their soil pests and diseases, and the risk of deficiencies (RHS).

Who this guide is for

Any vegetable garden structured in beds or squares (50 m² to 500 m²). Essential for intensively cultivated soils.

Why it matters

Limits the diseases and pests specific to one family, such as clubroot, by breaking their cycles (RHS; GAB/FRAB Bretagne). Saves nitrogen fertiliser thanks to the legume precedent. Lowers the risk of deficiencies by alternating different needs for nitrogen, phosphorus and potassium. Explores the soil at different depths by alternating taproots and fibrous roots (GAB/FRAB Bretagne).

What to understand before starting

A plan of the vegetable garden divided into 4 zones of comparable size.
A garden notebook to record each year's crops per bed.
Knowing the botanical family of your vegetables (see reminder below).

Detailed steps

Step 1
Map your beds
Divide the vegetable garden into 4 numbered beds. Make a simple sketch with orientation and aspect.
Step 2
Sort vegetables by family
Nightshades (tomato, pepper, aubergine, potato), Legumes (bean, pea, broad bean), Cucurbits (squash, courgette, cucumber, melon), Root vegetables and bulbs, from various families (carrot, beetroot, parsnip, onion, garlic).
Step 3
Choose an order, for example this one
Year 1: Legumes → fix nitrogen. Year 2: Nightshades → consume a lot of nitrogen. Year 3: Cucurbits → demanding in compost. Year 4: Root vegetables and bulbs → close the cycle, less demanding in manure.
Step 4
Shift each year
Each family moves one bed clockwise. Over 4 years, each bed will have hosted all 4 families.
Step 5
Intercrop green manures
Between two crops, sow phacelia or clover to cover the soil. Mustard is a brassica: do not sow it just before cabbages (RHS).
Step 6
Keep a journal
Note sowing date, varieties, problems encountered. It is the only way not to lose track after 2 years.

Concrete examples

Typical 4-bed plan A/B/C/D: Year 1: A=pea, B=tomato, C=squash, D=carrot. Year 2: A=tomato, B=squash, C=carrot, D=pea. And so on.
Small vegetable garden (3 squares): rotate over 3 years by grouping roots and cucurbits.

Common mistakes to avoid

Replanting tomatoes in the same spot every year: soil diseases build up there.
Forgetting the potato: it is a nightshade, to be grouped with the tomato.
Counting turnips and radishes as roots: they are brassicas, to keep with the cabbages in the rotation.
Noting nothing and forgetting everything over winter: rotation becomes impossible.

Tips & best practices

A cover crop (green manure) on any bed left free for more than 4 weeks.
Two other groups can be added, each on its own bed (5 or 6 beds instead of 4): the cabbage family (Brassicaceae, with radish, turnip and swede), especially if you grow a lot of them, and the onion family (garlic, onion, shallot, leek). The RHS makes them two separate groups.
Perennial aromatics (thyme, sage, rosemary): an out-of-rotation zone, along the edge.

Frequently asked questions

What about perennials (artichoke, asparagus)?: Out of rotation, in a permanent zone.
What if I grow on permanent mounds?: Rotation is still useful: rotate the families from one mound to another.
Can I shorten it to 3 years?: Yes: the SNHF (Jardiner Autrement) speaks of a minimum of three or four years. With tomatoes or potatoes, the RHS advises ideally at least 4 years.

Key takeaways

4 groups, 4 beds, 1 shift per year.
For example: legumes → nightshades → cucurbits → root vegetables.
Keeping a journal is non-negotiable.

Sources

Réseau GAB/FRAB Bretagne : La rotation en maraîchage, fiche technique Fruits et légumes n° 16 (agrobio-bretagne.org)
RHS (Royal Horticultural Society) : Crop rotation (rhs.org.uk/vegetables/crop-rotation)
SNHF, Jardiner Autrement : La rotation des cultures au potager (jardiner-autrement.fr)
RHS (Royal Horticultural Society) : Club root (rhs.org.uk/disease/club-root)