Crop Rotation by Plant Family

If you only learn one rule about rotation, make it this: do not follow a crop with a close relative. Here is how to apply that rule across a whole garden.

Key points

Rotate by plant family, not by crop name.
Track nine main families, and look up any new crop before placing it.
Pair rotation with sanitation and resistant varieties.
Cover crops belong to plant families too, so include them in the record.

Why rotate by family instead of by crop?

Pests and diseases usually attack related plants. A bacterial or fungal problem that hits tomatoes can often infect potatoes and peppers, and a pest that likes cabbage will happily eat kale and broccoli. If you rotate by name only, you may follow potatoes with tomatoes and think you have rotated.

Family rotation gives a rule that is simple to state and works for any crop you add later.

Another benefit is clarity. Once you have the family list in mind, decisions about where to put a new crop take seconds rather than a long search.

What are the main vegetable families to track?

Memorize the groups below and you can place almost any garden crop. When a crop is new to you, look up its family before assigning it a bed.

Many herbs and flowers also belong to these families, so include them in your planning if they share beds with vegetables.

If you ever grow unusual crops, look up the family in a trusted reference, and add it to your list so the record stays complete.

Nightshade: tomato, potato, pepper, eggplant
Brassica: cabbage, broccoli, kale, radish, turnip, mustard
Allium: onion, garlic, leek, chives
Legume: bean, pea
Cucurbit: cucumber, squash, pumpkin, melon, watermelon
Umbel: carrot, parsnip, celery, dill, parsley
Beet family: beet, chard, spinach
Composite: lettuce, sunflower
Grass: sweet corn

What rules make a good family rotation?

Keep the rules few so you remember them. Never plant a family in a bed where it, or a close cousin, grew last season. Where you can, leave a longer gap for families with known soil-borne troubles. Follow legumes with leafy or fruiting crops that appreciate available nitrogen. Avoid ending a season with a family that leaves a lot of disease-prone residue unless you can clean the bed properly.

Rotation works best with sanitation. Remove diseased plants rather than composting them in a pile that may not get hot enough, and ask your extension office what is advised for your disease.

Be careful with weeds as well. Many common weeds belong to the same families as vegetables, such as nightshade relatives and mustard relatives, and they can carry diseases between crops. Keeping beds weeded helps the rotation do its job.

How do you apply the rules to a real garden?

For example, suppose last year bed one held tomatoes and peppers, bed two held cabbage and kale, and bed three held beans and carrots. This year, bed one could take beans and carrots, bed two could take tomatoes and peppers, and bed three could take cabbage and kale. Each family has moved, and the nitrogen-friendly legumes now precede nothing in particular, so next year the pattern will shift again.

Check that no family sits next to its own relatives in the next bed in a way that offers pests an easy hop. Perfect separation is hard in small gardens, so aim for improvement, not perfection.

Do not overlook herbs. Basil, mint and sage belong to one family, while dill, parsley and cilantro belong to another, and putting dill next to carrots puts relatives side by side, which may matter if a shared pest is present in your area.

What about mixed beds and intercrops?

Mixed plantings complicate the record. Decide what counts as the bed's family, usually the main crop, and note the companions. For intercrops, record both families. A simple spreadsheet or notebook page with a row per bed and a column per year does the job.

If a bed holds many families in a small area, rotate the whole layout like a puzzle, shifting each family to the next position instead of tracking the bed as a unit.

For rows or beds planted in patches, a simple colored map keyed by family lets you see at a glance where the previous year's relatives were.

What are the exceptions and gray areas?

Some plants fit awkwardly. Potatoes are often grown like roots but are nightshades. Corn is a grass and is often treated as its own group. Perennial crops stay put and sit outside the plan. Cover crops belong to families too, so a brassica cover crop counts as a brassica in a rotation that is trying to avoid club root, for example, and a legume cover crop counts as a legume.

When in doubt, ask. Your extension office can confirm families and suggest how to handle your own mix of crops.

When to get local help: Your county extension agent can confirm plant families and suggest how long to wait before replanting a family in the same bed.

Sources and further reading

Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.

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