Companion Planting Guide for Australian Gardens
Proven plant pairings and essential companion flowers for productive gardens
Companion planting is the practice of growing certain plants together because they benefit each other. Some companions repel pests, some attract beneficial insects, some improve soil, and some simply grow well side by side without competing. It is not magic, but it is a practical tool that reduces pest pressure and makes the most of garden space.
This guide covers the best companion pairings for common Australian vegetable crops and the flowers every productive garden should include.
Companion Pairings by Crop
Tomatoes
Good companions: Basil (repels aphids and may improve flavour), carrots, lettuce, marigolds (repel nematodes), parsley, nasturtium (trap crop for aphids).
Avoid planting near: Brassicas (cabbage, broccoli), fennel, potatoes (share diseases).
Beans
Good companions: Corn (beans climb corn stalks), carrots, cucumber, lettuce, beetroot, marigolds. Beans fix nitrogen in the soil, benefiting neighbouring and following crops.
Avoid planting near: Onions, garlic, chives (alliums inhibit bean growth).
Carrots
Good companions: Onions and leeks (their scent confuses carrot fly), tomatoes, beans, lettuce, rosemary, sage.
Avoid planting near: Dill (can cross-pollinate and affect flavour), parsnips (attracts the same pests).
Brassicas (cabbage, broccoli, cauliflower, kale)
Good companions: Celery, dill, onions, chamomile, nasturtium (trap crop for cabbage white butterfly), alyssum (attracts predatory wasps).
Avoid planting near: Tomatoes, beans, strawberries.
Cucurbits (pumpkin, zucchini, cucumber, melon)
Good companions: Corn, beans (the classic "three sisters" planting), sunflowers, marigolds, nasturtium, borage (attracts pollinators).
Avoid planting near: Potatoes (compete for nutrients and share some pests).
Essential Companion Flowers
Every productive garden should include flowers. They attract pollinators and beneficial insects that control pests. Here are the five most useful companion flowers.
Marigolds (Tagetes)
The most valuable companion plant in the garden. French marigolds release compounds from their roots that suppress soil nematodes. They attract hoverflies (whose larvae eat aphids) and repel whitefly. Plant them through your vegetable beds, especially near tomatoes.
Alyssum (Sweet Alyssum)
Low-growing, white-flowered ground cover that attracts parasitic wasps, hoverflies, and lacewings. These beneficial insects control aphids, caterpillars, and other pests. Alyssum is perfect as an edging plant or ground cover between crops. Self-seeds freely.
Nasturtium
Works as a trap crop, attracting aphids and cabbage white butterflies away from vegetables. Also edible (flowers and leaves have a peppery flavour). Grows quickly and tolerates poor soil. Let it sprawl under fruit trees or along the edges of vegetable beds.
Borage
Excellent bee plant with blue, star-shaped flowers. Attracts pollinators to the vegetable garden, which improves fruit set on tomatoes, beans, cucurbits, and other crops. The leaves can be composted for potassium. Self-seeds enthusiastically.
Calendula (Pot Marigold)
Bright orange flowers that attract hoverflies and ladybirds. Also works as a trap crop for aphids. Edible petals add colour to salads. Easy to grow and self-seeds around the garden. Flowers through most of the year in mild climates.
The Three Sisters
The most famous companion planting combination. Corn, beans, and pumpkin (or other cucurbits) are planted together:
- Corn provides a tall structure for beans to climb
- Beans fix nitrogen in the soil, feeding the heavy-feeding corn and pumpkin
- Pumpkin spreads across the ground, shading out weeds and retaining soil moisture with its large leaves
Plant corn first and let it grow 15 to 20 cm tall before sowing beans at the base of each corn stalk and pumpkin seeds between the corn rows.
Plan Your Companion Planting
The Planting Season app shows companion planting suggestions for every crop in your garden.
Open the App →Frequently Asked Questions
Does companion planting actually work?
Some combinations are well-supported by research (marigolds suppressing nematodes, alliums deterring carrot fly). Others are based on generations of gardening observation rather than controlled studies. The evidence for flowering companions attracting beneficial insects is very strong.
What should I not plant near tomatoes?
Avoid planting brassicas (cabbage, broccoli), fennel, and potatoes near tomatoes. Potatoes and tomatoes share diseases (including blight) and should be kept apart. Fennel inhibits the growth of many plants.
Do marigolds really repel pests?
French marigolds (Tagetes patula) release compounds from their roots that suppress root-knot nematodes in the soil. This effect is proven by research. They also attract hoverflies (whose larvae eat aphids) and can repel whitefly. Plant them densely for the best effect.
What flowers attract bees to my vegetable garden?
Borage, alyssum, calendula, lavender, and sunflowers are all excellent bee plants. Borage is particularly effective near tomatoes and cucurbits because improved pollination directly increases fruit set and yield.
