Companion planting is usually presented as a list of pairs to memorise. It is more useful to understand why a pairing helps, because that tells you what to do when your beds do not match the list.
Most useful companion pairings do one of four things. Some plants attract predatory insects that eat the pests of their neighbour. Some confuse pests that hunt by smell, which is why strongly aromatic herbs turn up on so many lists. Some occupy a different layer of the bed, so a tall crop shades a heat-sensitive one or a shallow-rooted crop sits above a deep-rooted one without competing. And some simply fit the same conditions, so they can share a bed without one being watered wrongly for the other.
The pairings to avoid tend to have equally practical reasons: two plants in the same family sharing a pest, two heavy feeders competing for the same nutrients, or a vigorous sprawler smothering something slower.
Frequently paired for scent, pollinators or spacing.
The crops with the most recorded companions. Each row links through to the full plant guide, where spacing and sowing windows sit alongside the pairings.
| Crop | Grows well near | Keep apart from |
|---|---|---|
 Cabbage | Onion, Garlic, Rosemary, Sage, Dill, Thyme, Celery, Potato | Tomato, Strawberry, Grape |
 Beans | Carrot, Lettuce, Spinach, Corn, Pumpkin, Cucumber, Strawberry | Onion, Garlic, Fennel |
 Broccoli | Onion, Garlic, Potato, Rosemary, Sage, Thyme, Dill | Tomato, Pole Bean, Strawberry |
 Brussels Sprouts | Onion, Garlic, Rosemary, Sage, Thyme, Dill | Tomato, Strawberry, Pole Bean |
 Carrot | Tomato, Onion, Lettuce, Rosemary, Chives, Sage | Dill, Parsley |
 Cauliflower | Onion, Garlic, Rosemary, Sage, Dill, Celery | Tomato, Strawberry |
| Crop | Grows well near | Keep apart from |
|---|---|---|
 Marigold | Tomato, Capsicum, Eggplant, Cucumber, Squash, Beans | Nothing recorded |
 Nasturtium | Tomato, Cucumber, Pumpkin, Zucchini, Beans, Brassicas | Nothing recorded |
 Strawberry | Spinach, Lettuce, Beans, Borage, Onion, Garlic | Cabbage, Fennel, Broccoli |
 Tomato | Basil, Carrot, Marigold, Nasturtium, Parsley, Chives | Fennel, Potato, Kale |
 Cherry Tomato | Basil, Carrot, Marigold, Nasturtium, Parsley, Chives | Fennel, Potato, Kale |
 Roma Tomato | Basil, Carrot, Marigold, Nasturtium, Parsley, Chives | Fennel, Potato, Kale |
Companion planting is guidance, not a rule. Local conditions, bed size and what you actually want to eat all matter more than following a pairing exactly.
The crops that appear most often on other plants' avoid lists. These are worth knowing because a single misplaced plant can affect several neighbours.
A good pairing planted too close is worse than a mediocre pairing with room to breathe. Airflow between plants is one of the simplest ways to reduce fungal problems, so check the spacing figure on each plant guide before deciding how many companions fit.
Height matters as much as position. A tall crop on the sun-facing side of a bed will shade everything behind it, which ruins some neighbours and rescues others in hot weather. Each plant guide records a typical height.
Two plants that get on well but want very different amounts of water are awkward in one zone, because whatever schedule you set is wrong for one of them. Grouping by water need often matters more day to day than the pairing itself.
Companions are about what sits beside what. Rotation is about what follows what, season to season — see the crop rotation guide.
In a small plot, spacing and height matter more than pairing — see the small space guide.
Pairings behave differently in different gardens. Noting what worked in your beds is worth more than any general list, which is what the garden grid is for.
Some mechanisms are well established, such as aromatic plants disrupting pests that hunt by smell, and flowers drawing in predatory insects. Others are traditional advice with thinner evidence. Treating it as a sensible way to arrange a bed rather than a set of guaranteed rules is the practical approach.
Rather than one pairing, the most useful habit is keeping plants from the same family apart, since they share pests and diseases. That single rule prevents more problems than any individual good pairing creates.
They need their own space. Companion planting means nearby, not on top of each other. Check the spacing figure for each crop and treat that as the minimum.
Yes, and they are among the most useful additions. Many appear on companion lists because they attract beneficial insects or mask the scent of a crop. The encyclopedia includes herbs and flowers alongside vegetables for this reason.
Zones on the garden grid record what is planted where, so you can see which crops are actually adjacent rather than guessing from a plan on paper. Plant guides surface companion and avoid data as you assign crops.
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