In a rotation system, crops are grouped together according to preferred soil type, required nutrients and the types of pests and diseases that threaten them.

This often sees them grouped in families:

Roots (carrots, beetroot etc.)
Legumes (peas, beans)
Brassicas (cabbages, kale)
Allium or Onion family (garlic, onion, shallot)
Potato family (potato, tomato)
Curcubits (zucchini, pumpkin, cucumber).

These chosen groups of plants are grown together in separate beds/areas and moved to a different bed or planting area in the garden with each new season.

Healthy Soil
Crop rotation helps to prevent soil becoming over-populated with any one pest or the spores of a particular disease associated with a type of plant – such as blight spores building up in soil used repetitively for tomatoes and potatoes.

Shared benefits
Moving plants around the garden enables one group to benefit from the activity of another that has grown before it. For example:

Benefits of a rotation system between four plant groups:
Group 1 Legumes fix nitrogen into the soil. They grow on a well-composted soil and help improve its structure. They are followed by brassicas.

Group 2 Brassicas are nitrogen hungry. They hoover up the nitrogen left by the legumes and grow well on soil that has been well composted and where that compost is well-incorporated. Soil should be firmed before planting for stable root systems. Brassicas are followed by Alliums.

Group 3 Alliums like soil that has been composted for a previous crop – so not too rich. They like a fine soil that has been well broken up by the heavy roots of plants like brassicas. Alliums are followed by Roots.

Group 4 Roots like soil that has been composted for a previous crop (ie. so it is not too rich), well dug through and has a light, sandy texture – this allows plants to produce uniform roots that can easily penetrate the soil.

Crop rotation works well by general guidelines. Many of the separated groups will work when mixed and grown alongside or amongst each other.

Brassicas are companion plants for Alliums.

Alliums are companion plants for Roots.

Curcubits are companion plants for Legumes and Roots

You can go for a general sense of planting in groups and then mix things up with the following that can be planted here and there where space permits and appetite dictates:

Lettuce and all salads, annual herbs – basil, coriander, parsley, dill.

Flowers –marigolds (repel pests), calendula, zinnias, cosmos (attract predators) can all be planted amongst your crops. Biennial flowers such as borage and Cleome are best planted in any available areas around your beds – unless your beds are large.

Invasive but highly useful Comfrey should be planted where it can be contained from spreading its persistent roots (tyre stack, raised planter).

Once you have a basic structure to your planting and an understanding of what might work where you can start to diversify your planting wherever possible. This means popping the odd spare seedling or the end of a seed packet into any gaps that you spot or that become available once you are harvesting. There are very few plants that will specifically inhibit the growth of others when popped in and around as individuals.

(Florence fennel is one vegetable that is pretty much allelopathic to all other plants – this means it exudes chemicals that suppress growth in neighbouring plants. It still grow it in my beds but I give it a well –mulched buffer zone of about a hand’s length or two between it and other nearby plants.)

Spread bright, open-faced flowers throughout your beds and in the open ground around them – these will draw in beneficial insects. Let some of your vegetable plants flower so that they too can draw in beneficial insects. If flowers and vegetables self-seed in your beds, nurture the seedlings where possible so they can grow and mature  – they have found suitable conditions in which to grow.

FOUR year crop-rotation is fairly common and requires that you divide your beds or planting areas up into four areas.
The predominant groups for four areas/beds can be:

1. Legumes – Peas, Broad beans (dwarf and runner beans can be grown wherever)

2. Brassicas – Broccoli, Brussels sprouts, Cabbage, Cauliflower, Kale, Kohlrabi, Chinese Greens (Pak choi, Tatsoi) Radishes, Turnips, Silverbeet, Spinach.

3. Alliums – Onion, Garlic, Shallot, Leek, Spring onion, Chives. (can include curcubits)

4. Roots  – Beetroot, Carrot, Celeriac, Celery, Florence fennel, Parsley, Parsnip. (can include potatoes and tomatoes, kumara

There are three other groups that don’t need a designated place in a four bed system. These are best planted in additional planting areas outside the main four beds.

Potato family – Potato, Tomato, Kumara (Capsicum, Chilli, Aubergine are OK anywhere). Depending on how many of these you want to plant they can be incorporated into the Roots planting as well as containers (tyre stacks, tubs) and any extra beds you might have.

Curcubits – Cucumber, Marrow, Pumpkin and Squash, Zucchini. Depending on numbers these can be incorporated into the Allium planting as well as containers and any extra beds.

Permanents – Some plants stay in the ground year round – these need a location of their own:
Asparagus
Globe artichoke
Perennial herbs – Rosemary, Sage, Lavender, Thyme, Mint, Marjoram
Rhubarb
Soft fruits – Blueberries, Raspberries etc.

Bed numbering
It helps to sketch a rough plan and number your beds or planting areas from one to four and allocate plant groups as follows:

4 year rotation plan

YEAR ONE – This summer  –

BED 1 – Group 1 – Legumes

BED 2 – Group 2 – Brassicas

BED 3 – Group 3 – Onions

BED 4 – Group 4 – Roots

YEAR TWO – Next summer –

BED 1 – Group 2 – Brassicas

BED 2 – Group 3 – Onions

BED 3 – Group 4 – Roots

BED 4 – Group 1 – Legumes

YEAR THREE – Following summer –

BED 1 – Group 3 – Onions

BED 2 – Group 4 – Roots

BED 3 – Group 1 – Legumes

BED 4 – Group 2 – Brassicas

YEAR FOUR – end of first rotation –

BED 1 – Group 4 – Roots

BED 2 – Group 1 – Legumes

BED 3 – Group 2 – Brassicas

BED 4 – Group 3 – Onions

Typical spring/summer plantings in a FOUR bed rotation:

BED 1
Dwarf bean
Runner bean
Peas – mangetout, snap and sugar snap
Salads – lettuce, rocket, mizuna
3 sisters – Sweetcorn (min 20), runner bean, cucumber or squash
Calendula, French marigold, Zinnia, Viola (edges)
POST SUMMER – green manure Blue Lupin (maybe half the bed with other half planted in Broccoli, Cabbage, Kale)

BED 2 (watch out for cabbage white butterflies)
Kale
Cabbage
Broccoli
Cavolo nero
Silverbeet
Spinach
Pak choi
Radish
GROW THROUGH TILL APRIL – then compost for Garlic, Onion and Shallots in June and then Leeks in August

BED 3
Spring onion
Chives
Leeks
Salads
Space for – zucchini, cucumber, squash, melon
AT THE END OF SUMMER, clear and then lightly compost so you can grow roots and salads through winter – or green manure Blue Lupin

BED 4
Beetroot
Carrot (plant French marigold to deter root fly)
Florence fennel (plant separately within bed if possible)
Parsley
Salads
Space for – Tomato, Capsicum, Chilli, Aubergine
Maybe grow a pumpkin out to the side of your bed
CLEAR IN AUTUMN – compost and prepare to plant peas in Winter

Additional bed/planting area if you have one
Tomato
Runner bean
Sunflower
Cucumber
Salads

POST SUMMER – green manure (Broad bean)
Thereafter this bed can be used for crops you really like that are taken out of main 4 bed rotation. You will vary so as not to build up accumulation of pests and diseases. Use flowers and herbs as well as catch crops like salads for diversity.

THREE year crop rotation where a garden has three beds/planting areas
Group your plants as follows:

Group 1
Peas, climbing and dwarf beans, sweet corn, silverbeet, spinach, salads

Group 2
Cabbage, kale, broccoli, Brussels sprout, pak choi, kohlrabi, cauliflower, mizuna, swede, turnip, radish

Group 3
Tomato, potato, cucumber, squash, zucchini, aubergine, capsicum, pumpkin, Florence fennel, carrot, beetroot, celeriac, celery, parsnip, onion, garlic, leek, shallot,

At the end of each season:

Each group move round by one bed so that –
Group 1 is followed by Group 2
Group 2 is followed by Group 3
Group 3 is followed by Group 1