Tomato Companion Plants – What To Plant with Tomatoes

The ideal garden is diverse and self-reliant. I always advocate for using natural methods to avoid pests, increase yields, and promote a healthier garden.

In this article, I’ll share the best tomato plant companions to have in your garden. The best companion plants will form a symbiotic relationship with your tomatoes, helping the plants in one way or another.

Tomato Plant Spacing

Before I share my top companion plants for tomatoes, a quick note on tomato plant spacing. Above all, you should prioritize giving your tomatoes enough space.

There are tricks to growing more tomatoes in a smaller space (like growing vertically on a trellis), but nothing can replace proper spacing between plants. This physical space allows for improved airflow around the leaves, and reduced risk of disease.

As a rule, I recommend planting tomatoes at least 2 feet (~61cm) from other tomato plants. In addition, I will bottom prune the first 12-18 inches of leaves to improve ventilation around the plant base. Learn more about proper tomato spacing here.

These conditions apply to most standard size tomato plants. Even when planted all by themselves, they will need this space to grow and perform well in any garden.

Tomato Companion Plants

So, with an understanding of the basic space needs of tomatoes, let’s get into some of the best companion plants. These different plants will help tomatoes by attracting good insects, repelling pests, or simply making your harvesting more convenient.

1. Garlic

No matter where you live, chances are you can grow garlic in your climate. There are many studies indicating that companion planting with garlic reduces certain pest populations.

While it won’t completely eliminate any pest, garlic is a great companion for tomatoes in the garden. The small plants are easy to mix in with other plants throughout the garden, and are incredibly easy to grow.

Also, who doesn’t like cooking with garlic? If you’re growing lots of tomatoes, chances are you’ll want to make a tasty tomato sauce with homegrown spicy garlic – yum!

2. Basil

The classic tomato companion, in and out of the garden, is basil. This aromatic and tasty herb is easy to grow, and offers a host of benefits for your garden.

The aroma is said to deter some pests, and the root systems are not large enough to inhibit growth. Basil is also a much smaller plant, so it can be planted closer to tomatoes than other, larger crops.

Tip: In addition to the classic Genovese basil, try growing one of the many varieties of basil. My favorite is Thai sweet basil.

3. Alyssum

In my garden, flowers have become just as important as crops and herbs. Of course, we all know that flowers attract pollinators such as bees, wasps and flies.

However, you can also use flowers to attract predatory insects. Alyssum is an attractive, low-growing plant that attracts green lacewing and predatory wasps.

These are easy to grow and are sometimes used as a natural mulch around the base of tomatoes and other garden veggies. Sprinkle the seeds around the base of your tomatoes once they are outdoors, and you’ll have beautiful, small flowers from June through October.

4. Borage

If you’re looking for an easy-to-grow, flowering herb, borage may be perfect. If you want to attract more bees to your garden, borage can be a big help.

Although borage is technically an annual in cold climates, it is still considered somewhat invasive. This is because the plant will readily re-seed, often coming up as volunteer plants in early spring.

However, the sprouts are easy to recognize, and can be plucked away to allow just a couple plants grow out.

The flowers are edible, and taste great as a fresh addition to salads or steeped in cold water. The benefits outweigh the drawbacks for borage, and it makes for a great tomato companion plant.

5. Onions

Like garlic, onions make a good companion for tomatoes. They come from the allium family, all well known for helping deter certain pests.

Onions also require very little space to grow, so they can easily be interplanted amongst other, larger plants such as tomatoes. One method is to trellis your tomatoes vertically, and plant onions on the south side of the trellis. This allows both plants to get plenty of sun.

Tip: If you’d like to grow a salsa garden, plant tomatoes, bell peppers, jalapenos, garlic, onions, and cilantro together. They will benefit each other and can be harvested to make a fresh summer salsa!

6. Marigolds

Marigolds act as a ‘trap crop’ for nearby tomatoes, attracting aphids, spider mites, and snails. However, marigolds have also been shown to deter whiteflies. The marigolds release limonene in the air, which acts as a pest deterrent.

Tomatoes are notorious for attracting a host of pests, and whiteflies can be particularly pesky. Planting one or two marigolds near your tomatoes may help reduce whitefly populations.

Marigolds can also help reduce populations of root-knot nematodes. However, be sure to plant marigolds at least 2 months before your tomatoes go into the ground to see this effect.

Marigolds are an attractive, flowering plants the can attract good bugs to the garden. They’re easy to grow, non-invasive, and have a host of benefits for the garden.

7. Nasturtium

Another common trap crop is nasturtium. Trap crops are used to steer pests clear of your fruiting crops, like tomatoes. Nasturtiums are very attractive to aphids, making them a more likely target than your tomatoes.

The flowers, leaves, and seed pods are all edible on nasturtiums. This means the plant has multiple uses, not just as a sacrificial plant.

8. Leaf Lettuce

While lettuce doesn’t bring in beneficial insects, it can make great use of the space between tomatoes. Lettuces are typically cool weather crops, and many will bolt in hot temperatures.

Shade from the tomatoes will keep the lettuce cool when planted between tomatoes. After the first few harvests, it is best to remove the lettuce to allow the tomatoes to take advantage of the soil and nutrients.

9. More Flowers!

If it isn’t clear already, flowers make some of the very best companion plants for tomatoes. This is because they attract a wide variety of insects to your garden. The greater the diversity of insect life, the lower the chances of one pest getting a foothold in your garden.

Here are some other great flowers to plant with tomatoes:

• Cosmos. Cosmos are beautiful and attractive to a wide variety of pollinators and other beneficial bugs.
• Yarrow. Large, broad flower heads produce abundant blooms all summer. Attracts a wide array of pollinators and predatory insects.
• Echinacea. Also called coneflowers, these beautiful blooms will attract colorful butterflies, birds, and pollinators to the garden.
• Asters. Known to attract tons of pollinators, asters are a must-grow companion plant for any vegetable garden. They also come in a beautiful diverse range of colors and flower shapes.
• Zinnias. One of the easiest and most beautiful border flowers, zinnias are one of my personal favorite companion flowers. Plant directly after the risk of frost has passed for big blooms later in the year.

Essentially, the goal is to plant a wide range of flowers nearby and within your vegetable garden to attract diversity. This will make your garden a haven for life.

Plants NOT To Plant With Tomatoes

While some plants can bring benefits to your tomatoes, others can actually bring problems. Here are some plants to keep away from your tomato plants to avoid issues!

1. Fennel

Unfortunately, fennel gets a bad rap as a companion plant. This is a shame, since fennel is a delicious vegetable with aromatic flowers.

However, it is often said to cause problems for other nearby plants in the garden. The roots are said to secrete a substance that inhibits the growth of other surrounding plants, including tomato plants.

While I have not personally tested this (yet), I have heard from other growers that fennel had caused them issues in the past. To be on the safe side, I’d recommend planting fennel in a container rather than in the garden with your tomatoes.

2. Corn

Another crop that can cause a different problem for tomatoes is corn. The corn earworm may be one of the most destructive pests in North America.

This worm most commonly attacks corn, but it is known to feed on a variety of other plants, including tomatoes. The larvae of the corn earworm will most often feed directly on the tomato fruits, but may also eat foliage or burrow into the stems.

So, to avoid attracting the moths that bring these destructive larvae to the garden, don’t plant corn near your tomatoes. If you must have corn in your garden, consider skipping a year or two to keep the pests from establishing in your garden.

Tip: The earworm is most damaging later in the season, so be sure to harvest your tomatoes as soon as they are ready!

3. Cabbage/Brassicas

Brassicas, such as cabbage, broccoli, and kale, are heavy feeding plants. In other words, they require a lot of nutrients to grow well.

As a result, they will compete with nearby plants for nutrients, often taking away from them. If you plant tomatoes too close to cabbage or broccoli, the brassica may steal nutrients from your tomato, causing poor growth.

I love planting broccoli and kale, but I always make sure to give these plants plenty of space in the garden. Tomatoes have a relatively small root system, so be sure to space them at least 2-3 feet from any nearby brassicas.

4. Potatoes & Eggplants

Potatoes and eggplants are in the same plant family as tomatoes – they’re all nightshades (Solanaceae). As a result, most of them are susceptible to the same diseases and viruses.

To avoid a total loss of all of your nightshade plants, I would recommend separating the tomatoes from potatoes and eggplants. While diseases often find a way of spreading, you can make it less likely by preventing contact with other vulnerable plants.

In addition to separation, always remember to properly space your tomatoes, and practice good hygiene in the garden. This will reduce the chances of any disease getting a foothold in your plants.

While you can try your best each year to have a perfectly healthy garden, it is inevitable that you will face some issues. Remember to set realistic expectations, and grow a tolerance for a some pests and disease.

Each year is a learning experience, so take notes of what you saw this year to make next year an even better garden!