Why crop rotation matters

If you grow the same vegetables in the same spot year after year, you're inviting trouble. Soil-borne diseases such as clubroot in brassicas, white rot in onions and garlic, and potato eelworm build up in the soil. They don't just disappear; they wait for their favourite host plant to return. Crop rotation is simply the practice of moving plant families around your beds each season. It starves these pests and diseases, improves soil fertility, and helps you make the most of your space. Even a modest three-bed rotation can make a real difference.

Know your crop families

Before you plan, group your crops by family. The main ones for a British kitchen garden are:

• Legumes: peas, broad beans, runner beans, French beans. They fix nitrogen from the air into the soil.
• Brassicas: cabbages, kale, broccoli, sprouts, swede, turnips, radishes. They are heavy feeders and prone to clubroot.
• Roots: carrots, parsnips, beetroot. They prefer soil that hasn't been recently manured.
• Alliums: onions, garlic, leeks, shallots. They suffer from white rot.
• Potatoes: potatoes, tomatoes, peppers, aubergines. They are hungry and can carry blight and eelworm.
• Others: salads, courgettes, cucumbers, squash, sweetcorn. These are often fitted in wherever there is space.

For a small plot, focus on the big three: legumes, brassicas, and roots. They form the backbone of a simple rotation.

The classic three-bed rotation

The easiest system for a small kitchen garden is a three-bed rotation. Divide your growing space into three roughly equal parts. Each year, move each group one bed along.

• Bed 1 – Legumes: Sow peas, broad beans, or runner beans. They leave the soil enriched with nitrogen.
• Bed 2 – Brassicas: Follow with cabbages, kale, or broccoli. They love the nitrogen left by the legumes. Add lime if your soil is acidic.
• Bed 3 – Roots: Finish with carrots, parsnips, and beetroot. They don't need rich soil, so don't add fresh manure. The previous brassicas will have used the excess nitrogen, which is perfect for roots.

Next year, shift everything one bed to the right: legumes move to Bed 2, brassicas to Bed 3, roots to Bed 1. The following year, shift again. After three years, you're back to the start. This simple cycle prevents disease build-up and keeps your soil healthy. If you have room for a fourth bed, add potatoes and alliums as a separate group.

Fitting the rest of your crops into the plan

Not everything fits neatly into three beds. Here's how to handle the rest:

• Potatoes: They are bulky and prone to eelworm. Grow them in bags or a separate bed if you can. If not, treat them as a fourth group and rotate with the others. Never follow potatoes with tomatoes.
• Alliums: Onions, garlic, and leeks hate white rot. Keep them away from other alliums for at least three years. Grow them in a bed that follows brassicas, or in containers with fresh compost.
• Salads and herbs: These are short-term crops. Tuck them into gaps between rows or grow them in pots. They don't need a dedicated bed.
• Courgettes and squash: They are hungry and sprawling. Give them a corner of the legume bed or a large pot. Rotate them with the legumes if space allows.

Even if you can't rotate everything perfectly, moving your main crops is far better than doing nothing. A simple three-bed rotation helps beans, brassicas, and roots thrive.

Planning your rotation year by year

Let's put it into practice. Imagine you have three raised beds, each 1.2m by 2.4m. Here is a three-year plan:

• Year 1: Bed 1 – peas and broad beans. Bed 2 – cabbages and kale. Bed 3 – carrots and beetroot.
• Year 2: Bed 1 – carrots and beetroot. Bed 2 – peas and broad beans. Bed 3 – cabbages and kale.
• Year 3: Bed 1 – cabbages and kale. Bed 2 – carrots and beetroot. Bed 3 – peas and broad beans.

After year three, start again. Keep a notebook or a simple spreadsheet. Mark each bed with a label. Add compost to the legume bed in autumn. Lime the brassica bed in winter if needed. Never lime before planting potatoes, but since potatoes are optional here, you can lime the brassica bed freely. For roots, avoid fresh manure; use leafmould or well-rotted compost from the previous year.

If you have a disease outbreak, such as clubroot, remove and destroy the affected plants. Do not compost them. Extend the rotation for that family to five or six years if possible.