Companion planting is the practice of grouping vegetables that benefit each other, through pest confusion, shared nutrient needs, or physical structure, and keeping apart combinations that compete or share pests and diseases. It's not an exact science, but some pairings are widely and consistently recommended across New Zealand growing guides.
It's not an exact science, but some pairings are widely and consistently recommended across New Zealand growing guides.
Tomatoes do well alongside basil, carrots, celery, parsley, chives, onions, marigold and asparagus. Keep them well away from brassicas, fennel, potatoes and sweetcorn. Tomatoes and potatoes in particular share several diseases, including blight, so growing them near each other increases the risk to both.
Carrots pair well with bush beans, lettuce, onions, peas, radishes, leeks, sage and rosemary, but should be kept away from dill, parsnips, parsley and celery. Beans generally dislike the onion family (onions, garlic, leeks and chives) as well as tomatoes and capsicums, but grow well near carrots, cauliflowers, celery, cucumbers, marigolds and sweetcorn.
Broccoli does well near beetroot, celery, potatoes and onions, but should be kept away from oregano and strawberries. Cabbage shares many of the same good neighbours, but is choosier about what to avoid: keep it away from strawberries, tomatoes and runner beans, which compete for similar soil resources and can share pest pressure. Cauliflower does well near beans, celery, oregano, peas and nasturtiums, whose bright flowers act as a trap crop, luring aphids and cabbage white butterfly away from the crop, but like cabbage, should be kept away from potatoes, strawberries and tomatoes. Cucumbers do well next to beans, celery, onions and strawberries, but should be kept away from potatoes and strong-smelling herbs like basil.
Sweetcorn is a useful anchor plant: it works well with beans, celery, cucumbers, peas, radishes and potatoes, and climbing beans in particular can be trained up sweetcorn stalks once they're established, saving on trellis space. Onions and alliums generally pair well with brassicas, lettuces, strawberries, tomatoes and beetroot, but should be kept away from beans and peas.
None of this is a substitute for basics like crop rotation, adequate spacing and matching a plant's sun and water needs. But choosing companions deliberately, and avoiding the known bad pairings, is a low-effort way to reduce pest and disease pressure in a home garden.