Crop Rotation Guide

Crop rotation is one of the easiest ways to help keep your vege garden healthy and productive. All it means is not planting the same crops in the same spot every season.

Keeping a simple garden diary can help you keep track of where you plant each season or year to help break pest and disease cycles and prevent tired soil.

Why crop rotation matters

1. It helps stop pests and diseases building up

Many pests and diseases prefer one plant family. Some fungal spores can survive over winter, waiting for favourable conditions to return. Planting the same crop in the same spot each year makes it easy for these problems to settle in and build up over time. For example:

• Blight affects tomatoes and potatoes.
• Tomato and potato psyllid targets tomatoes, potatoes and eggplants.
• Carrot rust fly goes after carrots and other root veges.
• Cabbage white butterfly caterpillars love broccoli, cabbage and kale.

Many fungal and bacterial diseases, such as black spot, powdery mildew, and phytophthora root rot disease, often stick with one plant family. When you rotate crops, their favourite food isn’t waiting for them. For example, planting lettuce where the beans have been, or brassicas where the tomatoes were. This breaks the cycle and gives your soil a chance to recover.

2. It’s great for soil health

Different plants use nutrients at different rates. For example:

• Heavy feeders like tomatoes, corn, cabbage and broccoli pull lots of nutrients from the soil and need regular feeding.
• Light feeders like beans, peas and leafy greens use much less.
• Legumes (peas and beans) even add nitrogen back into the soil.
• If you keep planting heavy feeders in the same place, the soil can get worn out. Rotating crops spreads the demand so one area doesn’t get depleted.

Planning makes crop rotation easier

A little bit of planning saves a lot of guesswork.

• Draw a simple map of your garden beds.
• Write down what you plant and when.
• When a crop finishes, check your notes and choose a different crop family for that spot next season.

For example, if you grew broccoli (a brassica) in one bed this winter, plant peas or beans (legumes) there next season instead. A notebook or garden journal is all you need - nothing fancy!

How crop rotation works

Most gardeners use a four‑season cycle but the idea is flexible. You can group plants with similar needs and move those groups to a new bed each season. Plants are grouped based on the nutrients they use, the pests and diseases they attract and the type of soil they prefer. Here are two easy grouping options:

Option 1: Traditional crop groups

• Root vegetables:  Carrots, beetroot.
• Legumes: Peas, beans.
• Brassicas and leafy greens: Broccoli, cauliflower, cabbage, kale, spinach, lettuce, silverbeet.
• Onion family: Onions, garlic, leeks, shallots.
• Potato family (nightshades): Potatoes, tomatoes, eggplant, capsicums.
• Curcubits: Courgettes, cucumbers, pumpkins, squash.

Option 2: A simpler grouping

• Brassicas and salads: Cabbage, broccoli, cauliflower, kale, lettuce, silverbeet, mizuna, rocket.
• Mix of legumes, onions & others: Peas, beans, celery, onions.
• Root & fruiting veges: Potatoes, kūmara, yams, tomatoes, capsicum, chillies, pumpkins, carrots and courgettes.

Putting it into practice

• Choose your grouping system.
• Divide your garden into sections - one section per group.
• Plant each group in its own section.
• Next season, move each group to a new section. For example, brassicas move into the bed where legumes were, legumes move into the bed where roots were, and so on.

Over time, this simple rotation will keep your soil healthier, reduce pest pressure and help your plants grow better with less effort.

What if you don’t have space to rotate crops?

Not every garden is big enough for full crop rotation and that’s ok. If you’re planting in the same spot each season it just means your soil needs a bit more attention to stay healthy.

After a busy summer, your soil can be low in nutrients. To help it recover, mix in compost plus a nutrient boost like Tui Sheep Pellets or Tui Blood & Bone. Blend everything through the top layer of soil and water it in well so the nutrients start moving down to where the roots will be.

Remove any infected plant material as you spot it and dispose of it in the rubbish. Don’t add it to the compost as this can spread the insects and diseases you’re trying to prevent.