Why Rotation Matters More in a Small Plot

On a large field, a farmer can afford a few failures. On a kitchen garden of four or five beds, a bad season hurts. Pests that overwinter in the soil have nowhere to go if you grow the same family in the same spot year after year, and hungry crops will strip the same nutrients from the same patch until the soil gives up. Rotation is the oldest trick in the smallholder's book, and it costs nothing but a little planning on a wet January evening.

The principle is simple: group your crops into families, then move each family to a different bed each season. Most rotations run over three or four years, which suits the space most of us have. Three years is workable if you are tight for room; four is kinder to the soil.

Before you decide anything, draw your plot. Even a rough sketch on the back of an envelope will do, as long as it shows each bed, roughly how big it is, and which way it faces. North-facing beds warm up slowly, so keep them for brassicas and roots that tolerate a slower start.

The Four Families Worth Knowing

Almost everything you grow in a British kitchen garden falls into four groups. Learn these and the rotation almost designs itself.

• Legumes – peas, broad beans, runner beans, French beans. These fix nitrogen from the air into nodules on their roots. They leave the soil richer than they found it, which is why the next family in the sequence benefits so much.
• Brassicas – cabbage, kale, broccoli, sprouts, cauliflower, swede, turnip, radish, rocket. Heavy feeders that want that leftover nitrogen. They also suffer from clubroot, which lingers in soil for years, so they must never follow themselves.
• Roots – carrots, parsnips, beetroot, onions, leeks, garlic. Modest feeders. Fresh manure makes carrots fork and split, so these want ground that was manured the previous year, not this one.
• Potatoes – also tomatoes, peppers and aubergines, as they share the same family and the same blight risk. Potatoes break up heavy ground and are usually grown on a fresh muck dressing.

Leafy salads and herbs sit outside the system and can be tucked in wherever there is a gap, though avoid following lettuce with lettuce in the same spot if you can help it.

A Workable Four-Bed Plan

If you have four beds of roughly equal size, the rotation below will serve you well. Move everything on one place each year, clockwise. Write the year on your plan so you are not guessing next spring.

Year one – Bed A: potatoes with plenty of well-rotted manure dug in the previous autumn. Bed B: legumes, with lime if your soil is acid. Bed C: brassicas, planted after the ground has had a dressing of compost. Bed D: roots, on land manured last year.

Year two: everything shifts on one. Potatoes go to B, legumes to C, brassicas to D, roots to A. And so on. By year five you are back where you started, having given each bed a different diet and a different set of pests to cope with.

Three beds work too. Simply drop the roots into the legume bed as a follow-on crop after the peas come out in July, and rotate the other three around them.

Feeding the Soil as You Go

Rotation is only half the job. Each move is also a chance to feed the ground properly, and different crops want different things.

• Spread well-rotted manure or garden compost in autumn on the bed that will take potatoes the following year.
• Keep that same bed manured for the roots the year after – the residue is enough, and fresh muck causes forked carrots.
• Give brassicas a top dressing of compost or a handful of blood, fish and bone in midsummer when they look pale.
• Leave legume roots in the ground when you clear the plants. The nitrogen nodules release slowly into the soil for the brassicas that follow.
• Sow a green manure such as field beans or grazing rye on any bed that falls empty in September, then dig it in during February.

If you garden on clay, the potato year is your chance to break it up. On sandy soil, the legume and green manure years matter more, as organic matter leaches away quickly.

Pests, Disease and the Clever Shortcuts

The main reason most of us rotate is to break pest cycles. Clubroot in brassicas, potato cyst eelworm, onion white rot and carrot root fly all build up in the soil when their favourite crop returns too often. A four-year gap starves them out.

Some crops cheat the system. Carrots and onions grown in alternate rows confuse each other's flies, so a mixed bed of roots is fine. Tagetes planted among the brassicas is said to deter whitefly, and a row of nasturtiums will draw blackfly away from your broad beans.

Keep a note of what actually happened. A notebook with the bed letters and the variety grown each year is worth more than any fancy plan, because it tells you what worked on your soil, in your weather, in your garden. After three or four seasons you will have a rotation tuned to your plot, and a kitchen garden that gets a little easier and a little more productive every year.