Companion Planting Chart for SoCal Vegetables

Written by Kelsey W.

Companion plants are those that work well together for reasons like pest control, soil health, or simple space sharing. When your garden is in the planning stages, you can make some strategic decisions to plant species that grow well together and that will bring a natural balance to your garden.

Quick answer: The vegetable pairings that actually work are the ones with a real mechanism behind them. Corn, beans, and squash support each other structurally and nutritionally. Basil interplanted with tomatoes can confuse thrips and reduce hornworm egg laying. Nasturtiums lure aphids and squash bugs away from your crops. Legumes like peas, beans, and clover feed the soil nitrogen. Pair tall sun lovers with low, shade tolerant crops, and keep heavy feeders like cabbage and tomatoes apart. The chart below puts it all in one place.

If you’re thinking about planting a beautiful flowering plant that just happens to be the favorite food of a particularly vicious pest, there might be another plant you can place nearby that will attract other insects that will actually eat the pests you don’t want around. In other cases, planting certain fruit producing plants near one another can result in more bountiful harvests due to the way some plants attract pollinators. Insects like bees perform a vital function for the plants that need them to visit each year.

One thing worth knowing before you dig in: researchers who have tested the classic companion planting folklore have found that most of the old pairing charts are tradition rather than science. As Washington State University horticulturists put it, those lists have entertainment value more than scientific value. The good news is that several mechanisms are well documented: trap crops, nitrogen fixing legumes, interplanted flowers that feed beneficial insects, and smart use of space, according to University of Minnesota Extension. This guide leans on those proven pairings, so you can plan a garden that earns its keep.

How Do Companion Plants Work Together?

One of the most useful tricks is the trap crop: you “sacrifice” a plant so that your other plants won’t have to deal with an insect infestation. Aphids love eating nasturtiums, so you can plant nasturtiums nearby and they might forget all about the broccoli you’re also trying to grow. WSU Extension Master Gardeners recommend nasturtiums as a trap crop for exactly this job, and University of Minnesota Extension notes that research backs nasturtiums for reducing squash bug pressure too.

Another way companion plants work together is by feeding nutrients to one another. The classic example is the Three Sisters trio of corn, beans, and squash. The corn stalks give the beans a natural trellis to climb, the beans host bacteria on their roots that pull nitrogen from the air and feed the soil, and the big squash leaves act like a living mulch, shading the soil to hold moisture and crowd out weeds. That division of labor is documented by Cornell University researchers who studied traditional Iroquois plantings, and it still works in a Southern California backyard today.

Finally, some pairings are simply about sharing space well. Tall, sun loving plants can share a bed with lower, shade tolerant crops, so you harvest more from the same square footage, a principle Virginia Cooperative Extension highlights as one of the few scientifically grounded parts of companion planting.

Southern California Companion Planting Chart

Here is a quick reference chart for the most searched garden crops. Pairings marked “traditional” come from long standing garden charts rather than controlled studies, so treat them as a starting point, not a rule.

Crop	Plant it with	Keep it away from	Why
Tomatoes	Basil, lettuce, carrots	Cabbage and other brassicas, fennel	Basil can confuse thrips and reduce hornworm egg laying; brassicas compete for the same nutrients
Peppers	Basil, onions, carrots, lettuce	Fennel; beans in traditional charts	Low growers share space beneath taller pepper plants
Cucumbers	Beans, peas, radishes, lettuce	Strongly aromatic herbs in traditional charts	Legumes add nitrogen; radishes can serve as a flea beetle trap crop
Zucchini and summer squash	Nasturtiums, corn, beans	Potatoes in traditional charts	Research shows nasturtiums help reduce squash bug numbers
Beans and peas	Corn, cucumbers, carrots	Onions and garlic in traditional charts	Legumes fix nitrogen that feeds the soil around them
Lettuce and leafy greens	Sweet alyssum, taller crops like tomatoes	Few conflicts	Alyssum feeds hoverflies that eat aphids; light afternoon shade extends the season in SoCal heat
Corn	Beans, squash	Tomatoes in traditional charts	The original Three Sisters trio; corn and tomatoes share the same fruit eating caterpillar
Onions and garlic	Carrots, lettuce, brassicas	Beans and peas in traditional charts	Compact habit tucks neatly between rows
Fennel	Give it its own corner	Nearly all vegetables	UC Master Gardeners call fennel a poor companion, though its flowers feed beneficial insects

What Can You Plant with Tomatoes?

Basil, lettuce, and carrots are the companions with the best case behind them. Interplanted basil will help mask tomato plants from thrips, and surrounding tomatoes with basil has been shown to reduce egg laying by adult tomato hornworms, according to Penn State Extension. One honest note: there is no evidence that basil makes tomatoes taste better; that part of the folklore has never held up in testing. Lettuce is a practical partner because it uses the light shade at the feet of a tomato plant, which is a real advantage in our hot inland valleys.

On the keep away side, cabbage plants are voracious eaters when it comes to using the nutrients in their soil, and if you plant them near tomatoes, the tomato plants might not have enough strength to fight off the cabbage plants for their own nutrients. Fennel is another poor neighbor for tomatoes. And if aphids are your main tomato problem, start with our guide on how to aphid proof your plants.

What Grows Well with Cucumbers, Peppers, and Zucchini?

Cucumbers pair nicely with beans and peas, which feed nitrogen into the bed, and with quick crops like radishes and lettuce that fill the gaps while the vines get going. Radishes may also pull flea beetles away from your main crop: University of Minnesota Extension documents spicy brassicas as effective flea beetle trap crops, and radishes belong to that family.

Peppers do well with basil, onions, carrots, and lettuce tucked around them. The logic is mostly good space sharing: peppers grow tall and bushy while their companions stay low, so nobody fights for sun.

Zucchini and summer squash have the single best researched flower partner in the garden: nasturtiums. University of Minnesota Extension points to research showing nasturtiums help reduce squash bug populations, and the flowers are edible too. Corn and beans round out the squash bed the Three Sisters way.

One Southern California note: tomatoes, peppers, cucumbers, and squash are warm season crops you’ll plant in spring. If you’re reading this in fall or winter, build your pairings around cool season crops instead: lettuce, peas, carrots, and sweet alyssum all grow happily together right now, and our guide to vegetables you can grow in SoCal in the fall and winter covers the timing. Companion planting is a nearly year round sport here.

Flowers and Herbs That Earn Their Spot in the Vegetable Bed

A few flowers genuinely pull their weight between the vegetables. Sweet alyssum is the standout: UC IPM notes that commercial lettuce growers interplant quick flowering annuals like alyssum specifically to feed hoverflies, whose larvae are serious aphid predators. One caveat for our region: skip alyssum if Bagrada bugs have been building up in your area, since it is one of their favorite hosts. Nasturtiums earn their spot as a trap crop, luring aphids and squash bugs away from your edibles.

What about the famous pest repelling pairings, like marigolds against aphids or garlic against everything? Most of those claims have not held up well under research, and a few have a documented exception worth knowing about. We cover which repellent pairings are backed by evidence, and which are folklore, in our full guide to companion planting in Southern California.

Which Plants Keep Slugs and Snails Away?

No plant truly repels snails and slugs from a whole garden bed, but there are plants they mostly refuse to eat. That matters if you grow a big area of leafy vegetables, because snails and slugs can do serious damage overnight. UC IPM lists plants with stiff leaves or highly scented foliage, such as lavender, rosemary, and sage, along with ferns, cyclamen, hydrangea, California poppy, nasturtium, and lantana, as choices that resist snail and slug damage. So rosemary is a smart thing to plant in a snail prone corner because the snails will leave it alone, and you get a kitchen herb in the bargain, just don’t count on it to shield the lettuce next door.

For the plants snails do love, UC IPM recommends the controls that actually work: handpick on a regular schedule, put a copper band around raised beds or pots, use an iron phosphate bait, and switch from sprinklers to drip irrigation so the garden stays drier and less inviting.

Companion Plants That Build Better Soil

The legume cover crop is the backyard version of crop rotation: planting clover, beans, or peas between vegetable crops feeds the soil so the next planting has a happy home. Farmers rotate crops between fields for the same reason, and the principle scales down to a single raised bed.

Clover grows swiftly, and you can use it to infuse the soil with nitrogen after you take out one set of plants and before you plant another. Legumes like clover host Rhizobium bacteria on their roots that fix nitrogen from the air into the soil, which is why UC Master Gardeners recommend legume cover crops when the goal is feeding the next round of crops. The roots even loosen the soil as they grow, making it an ideal place for new plantings when the planting season comes along.

If you’re thinking about a flower garden, lupine is a true nitrogen fixer: like beans and peas, it is a legume that fixes atmospheric nitrogen through bacteria on its roots. As far as appearances go, lupine is a great companion for tulips since they both flower in spring, and irises pair beautifully with lupines too.

Sunflowers, on the other hand, are often recommended as soil builders, but the research says the opposite: sunflowers are allelopathic, meaning they release compounds that can suppress the growth of nearby plants, per University of Illinois Extension. They’re still a joy to grow, just give them a spot at the edge of the garden rather than the middle of the vegetable bed, and skip the old advice about planting winter vegetables where the sunflowers stood.

What Should You Not Plant Together?

In the same way that some plants work together when they’re planted next to one another, other pairings might not fare so well when nutrients or space run short. A few combinations to avoid:

Two heavy feeders in one spot. Cabbage and tomatoes both eat voraciously, and planted together they compete for the same nutrients. Give heavy feeders their own space or pair them with light feeders.
Tall plants shading sun lovers. Shade is a gift to lettuce in a SoCal summer and a problem for peppers. Think about mature heights before you plant, since smart spatial pairing is one of the best documented parts of companion planting.
Onions and garlic next to beans and peas. This one comes from the traditional charts, including the compatibility table published by Virginia Cooperative Extension, rather than from controlled studies, but it costs nothing to honor it since alliums tuck in happily beside carrots, lettuce, and brassicas instead.
Fennel near almost anything. UC Master Gardeners of Riverside County flag fennel as a poor companion plant. Give it its own corner where its flowers can still feed beneficial insects.

You don’t really need to worry about these ill pairings if you’re going with a container garden, and you probably don’t even need to focus on the complexities of crop rotation unless you’re going full bore into urban farming at your SoCal home. There are no absolutes when it comes to gardening, but a little knowledge can go a long way. When creating your future garden, start with a list of the plants you’d like to have, whether they’re vegetables you’d like to harvest for family meals or flowers you want to enjoy, and look at their nutrient needs, mature sizes, and what sorts of pests they might attract or repel. If you want harvests fast, our list of the fastest growing vegetables for your SoCal garden is a good place to start pairing.

Find Your Friendly Companion Plants at Green Thumb Nursery

Green Thumb Nursery offers all the information and help you need to create an amazing outdoor space for your home. Whether you live in an apartment and want to create a healthy container garden or you want to fill your home’s yard with healthy plants, the experts at Green Thumb Nursery can help you make the right decisions for your yard. Drop by one of our five Southern California garden centers for your next beautiful plant, and bring your garden plan with you. Our nursery pros love a good pairing puzzle.

Companion Planting FAQ

What vegetables grow well together?

Corn, beans, and squash are the classic proven trio: corn supports the climbing beans, beans fix nitrogen into the soil, and squash leaves shade the soil like a living mulch. Other reliable pairings include tomatoes with basil and lettuce, cucumbers with beans and radishes, and any leafy greens with sweet alyssum to attract aphid eating hoverflies.

What can you plant with tomatoes?

Basil, lettuce, and carrots are the best companions for tomatoes. Penn State Extension reports that interplanted basil helps mask tomatoes from thrips and reduces hornworm egg laying, while lettuce thrives in the light shade beneath the plants. Keep cabbage, other brassicas, and fennel away from tomatoes.

What should you not plant next to tomatoes?

Keep cabbage and other brassicas away from tomatoes, since both are heavy feeders that compete for the same nutrients, and keep fennel out of the tomato bed entirely. Traditional charts also separate tomatoes from corn because both crops host the same fruit eating caterpillar.

Can you plant sweet potatoes with tomatoes?

It is better to give sweet potatoes their own bed. Both crops are heavy feeders, and sweet potato vines sprawl aggressively enough to smother a tomato planting by late summer. If space is tight, grow sweet potatoes in a separate container or train the vines away from the tomatoes.

What grows well with cucumbers?

Beans, peas, radishes, and lettuce all grow well with cucumbers. Beans and peas add nitrogen to the bed, while radishes can act as a trap crop that draws flea beetles away from the vines. Quick salad crops fill the space while young cucumber vines get established.

What grows well with peppers?

Basil, onions, carrots, and lettuce are good companions for peppers. The pairing logic is space sharing: peppers grow tall and bushy while these companions stay low, so the bed produces more without competition for sun. In Southern California, peppers are a warm season crop, so plant these combinations in spring.

What plants repel slugs and snails?

No plant truly repels slugs and snails from a garden bed, but UC IPM lists plants that resist their feeding, including lavender, rosemary, sage, ferns, cyclamen, hydrangea, California poppy, nasturtium, and lantana. Plant those in snail prone spots, and protect tastier crops with handpicking, copper barriers, iron phosphate bait, and drip irrigation.

Sources

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