Companion planting

Some plants can attract or repel insects, give shade or provide nutrients and support to others.

Taking advantage of this when growing vegetables, herbs and flowers is called companion planting.

This page explains some of the benefits of companion planting and how to choose good plant matches.

Benefits

Companion planting can help you grow healthier plants and cut down on chemicals and pesticides.

Add nutrients

Plants like beans, peas and clover can add nutrients to your soil and reduce the need for fertiliser.

You can also mulch these plants into the soil as a good source of nitrogen.

Beans and corn are often planted together. The corn provides support for the bean. The bean gives off nutrients for the corn.

Repel pests

Some plants give off chemicals that repel pests.

Marigold, for example, repels nematodes - a pest that feeds on the roots of your plants. This makes marigold a useful companion for many garden crops.

Other plants can help keep pests in check by attracting predators. Dill, for example, attracts a wasp that feeds on worms and caterpillars.

Control weeds

Some plants release chemicals that slow other plants' growth. These can help to control weeds.

Grain rye hay gives off chemicals that can stop seeds from germinating. If you use grain rye hay as mulch, you can stop weeds from sprouting without harming seedlings.

Grow more

Planting flowers near fruit and vegetables will attract pollinators.

Tall, sun-loving plants such as corn can give shade to plants like pumpkins or squash. This is a good use of space and will let you grow more plants and vegetables in a small garden.

Good companions

Read below for a list of common garden crops and their useful combinations.

Crop	What to plant with and effect
Basil	Repels flies and mosquitoes. It can improve tomato growth and flavour.
Beans	Beans add nitrogen to the soil. They go well with most vegetables and herbs.
Bush beans	Grow well with corn, sunflowers, cucumber and celery
Cabbage	Grow with aromatic herbs like dill to keep off worms. Tomatoes also repel moth larvae that eat cabbages.
Celery	Improves leek, cauliflower, cabbage and tomato growth. Repels white cabbage butterflies.
Chives	Plant around the base of fruit trees to stop insects climbing the trunk
Corn	Provide support for plants like cucumber, squash and pumpkin. Plant with beans or peas, which add nitrogen to the soil.
Cucumber	Planting cucumber near radish plants will improve growth. Sunflowers can provide shade, while beans and peas add nitrogen.
Dill	Dill improves cabbage growth and health. It attracts beneficial wasps that control cabbage pests.
Eggplant	Beans add nitrogen. Marigolds encourage growth and deter pests.
Marigolds	Plant throughout the garden to keep soil free of nematodes. Marigold also deters many other insects.
Nasturtium	Plant under fruit trees. Deters aphids, bugs, pumpkin beetles and pests of the cucurbit family.
Parsley	Improves growth and flavour of tomato and asparagus. Attracts bees and ladybirds and deters some pests.
Peas	Plant near carrots, radish, cucumber, corn, beans and squash. Adds nitrogen to the soil.
Petunias	Plant throughout the garden and to repel tomato worm and asparagus beetle
Pigweed	Pigweed is good for potatoes, onions and corn. It keeps weeds under control. It also keeps leaf miners away from other crops like capsicums.
Radish	Plant radish near peas for nitrogen. Lettuce and cucumber can improve radish growth. Nasturtium repels aphids, beetles, white flies and other bugs.
Squash	Plant under corn for shade and support. Marigold will encourage growth and deter nematodes. Nasturtium deters pests.
Tomato	Planting near parsley, basil, asparagus, chives, onions or cucumber improves growth and flavour. Marigold and nasturtium deter nematodes and pests.

Bad companions

Some plants do not grow well together. These are called bad plant companions. Common bad plant combinations are listed below.

Crop	Plants to avoid
Corn	Avoid planting corn near tomatoes
Cucumbers	Cucumbers don't like aromatic herbs
Fennel	Most plants dislike fennel because of the chemicals released. Fennel can attract beneficial insects.
Onions	Avoid planting onions with corn, cabbage, peas or beans
Potatoes	Potatoes don't like pumpkin, squash, tomato, cucumber or sunflowers
Walnuts	Walnuts secrete a chemical through their roots that is poisonous to most plants

Sometimes when plants are grown together only one of them will benefit. This is called a one-way relationship.

For example, tomatoes repel caterpillars that eat cabbages but get no benefit in return.

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