A companion planting chart shows which plants grow well together in the same bed. The idea is simple: some plants help each other by shading the soil, attracting pollinators, confusing pests, or using different depths of soil, while others compete for the same light, water and food, or share the same pests. A good chart helps you plan a bed so that every plant has a good neighbour, and a poor combination is avoided. This guide gives a chart based on our crops data, explains how to use it, and is honest about what is known and what is traditional belief rather than proven fact.
The pairings in the chart below come from our crops data file, which lists companion plants for each crop from standard public horticultural references. Where a pairing is a matter of traditional belief rather than something the data establishes — for example, that a herb is traditionally said to improve the flavour or growth of a neighbour — this guide labels it as traditionally said to, because folk claims about companion planting are widely repeated but not always tested. The chart is a planning aid, not a guarantee: good soil, water, light and spacing matter far more than any pairing, and a well-tended bed of plants that are not ideal companions will outperform a neglected bed of perfect companions. Our companion planting finder lets you look up companions for a specific crop, and our growing guides give crop-by-crop detail.
The companion planting chart
The table below lists the main crops in our data and the companions listed for each. Use it to plan a bed: plant a crop next to one or more of its listed companions, and avoid planting it next to a crop that shares its pests or competes for the same space.
| Crop | Good companions (from our crops data) |
|---|---|
| Tomatoes | Basil, marigolds, carrots, onions, parsley |
| Bell peppers | Basil, onions, tomatoes, marigolds, carrots |
| Hot peppers | Marigolds, basil, onions, lettuce |
| Cucumbers | Beans, corn, peas, marigolds, dill |
| Lettuce | Carrots, radishes, strawberries, cucumbers, onions |
| Carrots | Onions, lettuce, rosemary, tomatoes, sage |
| Green beans | Marigolds, basil, onions, lettuce |
| Peas | Marigolds, basil, onions, lettuce |
| Potatoes | Beans, corn, cabbage, marigolds, horseradish |
| Zucchini | Marigolds, basil, onions, lettuce |
| Eggplant | Marigolds, basil, onions, lettuce |
| Sweet corn | Marigolds, basil, onions, lettuce |
| Broccoli | Marigolds, basil, onions, lettuce |
| Cabbage | Marigolds, basil, onions, lettuce |
| Kale | Marigolds, basil, onions, lettuce |
| Spinach | Marigolds, basil, onions, lettuce |
| Beets | Marigolds, basil, onions, lettuce |
| Radishes | Marigolds, basil, onions, lettuce |
A few patterns are clear from the data. Marigolds appear as a companion for almost every crop, because they are traditionally said to deter soil pests and to attract pollinators, and they are easy to grow in any bed — see growing marigolds. Basil appears with tomatoes, peppers, beans and many other crops, and it is traditionally said to improve the growth and flavour of tomatoes, though that claim is traditional rather than proven. Onions appear with many crops, and they are traditionally said to confuse pests with their strong scent. Carrots and onions are a classic pairing in the data: carrots are listed with onions, and onions with carrots, and they use different depths of soil, so they do not compete directly. Cucumbers with beans, corn and peas is another classic combination, because the beans fix nitrogen in the soil and the corn can support the beans, while the cucumbers spread below. Lettuce with carrots, radishes and strawberries works because lettuce is shallow-rooted and fast, while carrots and radishes use deeper soil and are ready at different times.
How to use the chart in a real bed
Start with the crop you most want to grow, and choose one or two companions from its row in the chart. A bed of tomatoes with basil and marigolds around the edge is the classic example: the tomatoes grow tall, the basil fills the space below them, and the marigolds edge the bed and attract pollinators. A bed of carrots with onions and lettuce uses three depths of soil and three harvest times, so the bed is productive all season. A bed of cucumbers with beans and peas uses the vertical space as well as the ground, because the beans and peas climb while the cucumbers spread below. Our guides for growing tomatoes, growing carrots, growing lettuce and growing cucumbers give the spacing and timing for each crop.
Do not try to plant every companion at once. A bed crammed with six different crops will be overcrowded, and overcrowding causes poor air circulation, disease and low yields. Choose two or three crops per bed, give each the spacing it needs, and rotate the bed next year so the same crop does not grow in the same place season after season. Crop rotation matters more than companion planting for preventing soil-borne disease, because many pests and diseases build up in the soil when the same crop is grown in the same place year after year. Keep a simple plan of what you planted where, so you can rotate properly.
Flowers and herbs as companions
Flowers and herbs earn their place in a vegetable bed. Marigolds are the most useful: they are easy to grow, they flower all summer, they attract pollinators and hoverflies, and they are traditionally said to deter soil pests. Nasturtiums attract aphids away from vegetables, acting as a sacrificial plant, and their flowers are edible. Borage attracts bees and is traditionally said to help strawberries and tomatoes. Dill attracts hoverflies and other beneficial insects, and it is listed as a companion for cucumbers in our data. Lavender, rosemary and sage attract pollinators and are traditionally said to confuse pests with their strong scent, though that claim is traditional rather than proven. Our guides for growing lavender, growing rosemary and growing basil cover the herbs most often used as companions. Plant flowers and herbs around the edge of a bed or in the gaps between vegetables, so they do not crowd out the crop.
What companion planting cannot do
Companion planting is a useful planning aid, but it cannot fix poor soil, too little water, too little light, or overcrowding. A tomato planted next to basil in poor, dry soil will still struggle, and a bed of perfect companions that is never watered will still fail. Companion planting also cannot replace pest control: marigolds will not stop a bad aphid outbreak, and onions will not stop carrot fly on their own. For pest problems, use the methods in our pest guides — slug control, aphids control — and the pest identifier helper to work out what you are dealing with. And treat folk claims with care: when a book or a website says that a herb improves the flavour of a neighbour, or that a flower repels a specific pest, it is often repeating a traditional belief that has not been tested in a controlled trial. That does not mean the pairing is useless — many traditional pairings work well for practical reasons, such as different root depths, different harvest times, or attracting pollinators — but it does mean you should not rely on a pairing to solve a problem that needs a real solution, such as a fence for deer or a mesh cover for carrot fly. If you are unsure what will grow well together in your area, check your local extension service for advice.
Planning a companion-planted bed step by step
First, list the crops you want to grow and check the chart for their companions. Second, group crops that share companions and that need similar water and sun — tomatoes, peppers and basil all like sun and rich soil, while lettuce, spinach and radishes like cooler conditions and can share a shadier bed. Third, draw the bed on paper, putting tall plants on the north side so they do not shade shorter ones, and leaving space to reach every plant. Fourth, sow or plant at the right time, using the seed starting calculator and the frost date calculator to plan dates. Fifth, keep a record of what you planted where, so you can rotate next year and learn which pairings worked in your garden. A companion-planted bed that is well watered, well fed, well spaced and rotated will give a better harvest than a bed planned on pairings alone.
Common mistakes
The most common companion planting mistakes are planting too many companions in one bed so everything is overcrowded, believing that a pairing will solve a pest problem on its own, planting companions that need different water or sun together, and growing the same crop in the same place year after year because the companions were right. Another is copying a chart without checking it against your own garden: a pairing that works in a sunny, dry garden may not work in a shady, wet one. Use the chart as a starting point, give plants the space, water and light they need, rotate your beds, and keep a record of what worked. Your own garden is the best test of any companion planting claim.
Frequently asked questions
What is the best companion for tomatoes?
According to our crops data, tomatoes grow well with basil, marigolds, carrots, onions and parsley. Basil is the classic companion, and it is traditionally said to improve the growth and flavour of tomatoes, though that claim is traditional rather than proven. Marigolds edge the bed and attract pollinators, while carrots and onions use different depths of soil.
Do marigolds really keep pests away?
Marigolds are listed as a companion for almost every crop in our data, and they are traditionally said to deter soil pests and to attract pollinators and beneficial insects. They are useful in any bed, but they will not stop a serious pest outbreak on their own — they are a supplement to good gardening, not a substitute for pest control.
Can I plant carrots and onions together?
Yes. Carrots and onions are a classic pairing in our data: carrots are listed with onions, and onions with carrots. They use different depths of soil, so they do not compete directly, and onions are traditionally said to confuse carrot pests with their strong scent, though that claim is traditional rather than proven.
What should not be planted together?
In general, avoid planting crops from the same family together, because they share pests and diseases — for example, do not plant tomatoes, peppers and potatoes in the same bed year after year. Avoid planting tall, vigorous crops where they will shade shorter ones, and avoid crowding any bed. Rotate crops each year so the same crop does not grow in the same place.
Is companion planting scientifically proven?
Some pairings have a clear practical basis, such as different root depths, different harvest times, or attracting pollinators, and these are well supported by experience. Other claims — for example, that a herb improves the flavour of a neighbour — are traditional beliefs that have not been tested in controlled trials. Use the chart as a planning aid, and judge pairings by how they perform in your own garden.