11 Worst Companions For Tomatoes (+ The 5 Best)

bumper crop of tomatoes in garden
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11 Worst Companions For Tomatoes (+ The 5 Best)

Tomatoes are everyone's summertime favorite. Whether you’re using them in salads, salsas, or burger toppings, you expect a hearty harvest every year. But, did you know that certain plants can harm your tomatoes if planted too close?

Here we are diving into the worst companion plants for tomatoes and what to plant in place. This way you will avoid pests and disease while reaping the benefit of yummy homegrown tomatoes

What is Companion Planting?

Companion planting is a gardening technique where certain plants are planted close together to enhance growth, protect against pests, and improve overall yields. It’s like creating a mini-ecosystem in your garden, where plants help each other thrive. 

However, not all plant combinations are beneficial. Some plants can harm tomatoes by competing for nutrients, attracting pests, or spreading diseases.

11 Worst Plants to Plant with Tomatoes

ear of corn in the gardenear of corn in the garden

1. Corn

While corn and tomatoes might seem like a great summer pairing, they’re not the best companions in the garden. Their shared pests, such as tomato hornworms and corn earworms, can damage both plants. 

Additionally, both crops are heavy feeders, competing for essential nutrients like nitrogen and phosphorus.

Corn and tomatoes also share vulnerabilities to similar fungal diseases, increasing the likelihood of infections spreading. Lastly, the tall stalks of corn can overshadow tomato plants, blocking the sunlight they need to grow. As a result, it’s not recommended to plant these two near each other.


ripe eggplants on the vine in gardenripe eggplants on the vine in garden

2. Eggplant

Eggplants and tomatoes belong to the same plant family, Solanaceae, which makes them prone to similar issues. Tomato hornworms, aphids, and Colorado potato beetles can infest both plants. 

They’re also susceptible to blight and verticillium wilt, which can spread easily. 

Both need high amounts of nitrogen, phosphorus, and potassium, and their similar growth habits can lead to poor airflow and increased pest habitats.


head of broccoli in gardenhead of broccoli in garden

3. Broccoli

Broccoli might seem harmless, but its presence near tomatoes can cause trouble. It releases compounds that inhibit tomato growth, a process known as allelopathy. 

Broccoli demands high nitrogen, while tomatoes need a balanced nutrient profile. Moreover, tomatoes dislike overwatering, while broccoli thrives in moist conditions.


freshly harvested potatoes in gardenfreshly harvested potatoes in garden

4. Potatoes

Potatoes and tomatoes are a risky pair in the garden. Both are highly susceptible to late blight, a devastating fungal disease that can spread rapidly and cause significant damage to crops. 

As heavy feeders, these plants vie for the same essential nutrients in the soil, which can lead to nutrient depletion and less than optimal growth for both. 

Additionally, their root systems can overlap, creating competition for water and space. This causes stunted growth for both plants, and neither matures far enough to propeller fear fruit. 


one cucumber on the vine in gardenone cucumber on the vine in garden

5. Cucumbers

Cucumbers and tomatoes might sound like a salad dream, but in the garden, they’re not friends. Both are prone to powdery mildew and fusarium wilt, and pests like aphids, whiteflies, and spider mites can attack both plants. 

While cucumbers prefer consistently moist soil, tomatoes need drier conditions.


pea pods on the vine in the gardenpea pods on the vine in the garden

6. Peas

Peas are nitrogen-fixing legumes, but they’re not ideal companions for tomatoes. 

Excessive nitrogen can inhibit tomato growth. Pea vines can interfere with tomato cages or supports, and both are susceptible to fusarium wilt and powdery mildew.


fennel plant growing in the gardenfennel plant growing in the garden

7. Fennel

Fennel is notorious for being a poor companion to most plants, including tomatoes. 

Its chemical compounds can stunt tomato growth, and it attracts aphids, which can easily spread to tomatoes. 

Its robust root system also competes for water and nutrients and can stunt the growth of both plants, not allowing either of them to fully grow.


dill plant growing in terra cotta potdill plant growing in terra cotta pot

8. Dill

Don't make it a big “dill”, and keep this plant in a separate area of the garden. Dill is a tricky herb when it comes to companion planting. As dill matures, it releases chemicals into the soil that can inhibit the growth of neighboring plants like tomatoes, which is called allelopathy. 

Both plants have large root systems that compete for essential resources such as water and nutrients, potentially stunting the growth of tomatoes. Dill’s tall, feathery leaves can also create shading issues, reducing the sunlight tomatoes receive.

While young dill plants may not pose significant problems, mature dill can disrupt tomato growth substantially, making it a less-than-ideal companion in your garden.


salmon orange dianthus Plant Havensalmon orange dianthus Plant Haven

9. Sunflowers

Sunflowers might add beauty, but they’re problematic neighbors for tomatoes. Their impressive height can cast significant shadows over tomato plants, depriving them of sunlight.

Additionally, sunflowers have deep and extensive root systems that dominate the soil, monopolizing water and essential nutrients, which can leave nearby tomato plants struggling. 

Lastly, sunflowers attract pests such as aphids and beetles, which can easily migrate to tomatoes and cause additional damage. While they add visual appeal and attract pollinators, their competitive nature makes them poor companions for tomatoes.


sprigs of rosemary in sunlightsprigs of rosemary in sunlight

10. Rosemary

Rosemary thrives in dry soil, which contrasts sharply with the consistent moisture that tomatoes require for healthy fruit production. 

Additionally, rosemary has minimal nutrient needs, while tomatoes are heavy feeders that demand a nutrient-rich environment, creating a mismatch in soil resource requirements. 

The sprawling growth habit of tomato plants can further complicate this pairing by overshadowing rosemary, limiting its access to the sunlight it needs to thrive.


salmon orange dianthus Plant Havensalmon orange dianthus Plant Haven

11. Peppers

Peppers, like tomatoes, belong to the Solanaceae family, making them poor companions in the garden. Both plants attract pests such as tomato hornworms and aphids, which can quickly infest and damage them. 

Additionally, they are susceptible to similar diseases, such as blight, which can easily spread between the two when grown in close proximity. 

Being heavy feeders, peppers and tomatoes compete intensely for nutrients like nitrogen and phosphorus, which can lead to reduced growth and lower yields for both plants.


Top 5 Companion Plants for Tomatoes

Now that we have the plants we shouldn't keep near tomatoes, here are five of the best companion plants that help your tomato plants thrive.

1. Basil

Basil is a standout companion, as it minimizes pests, improves tomato flavor, helps prevent fungal diseases like powdery mildew, and enhances airflow around tomato plants.

2. Chives

Chives are another excellent choice, deterring aphids and other pests while releasing compounds into the soil that boost plant health and help prevent fungal infections.

3. Garlic

Garlic is a powerhouse for reducing harmful insects like aphids and whiteflies. Its natural antifungal properties prevent diseases, and it promotes overall plant and soil health.

4. Lettuce

Lettuce is a great companion for tomatoes because it thrives in the shade of tomato plants, maximizes garden space without competing for sunlight, and helps maintain soil moisture by reducing evaporation.

5. Marigolds

Lastly, marigolds not only add beauty to your garden but also repel nematodes, aphids, and tomato hornworms, attract beneficial insects like ladybugs and pollinators, and suppress soil-borne diseases.

The Top Benefits of Companion Planting

Companion planting isn’t just about saving space—it’s a game-changer for a healthier, more productive garden overall. Here are some more benefits you can start to plan for:

Pest Control

Plants like marigolds have amazing natural repellent power, keeping away nematodes and aphids. Want to plant more herbs? Basil is not only delicious but can also prevent mosquitoes, flies, and aphids from snacking on your plants! 

Better Harvests 

Optimize space by planting your tomatoes, basil, and lettuce in the same garden bed. They all provide excellent benefits to one another and make it super easy to throw together a summer salad. 

Improved Soil Health

Legumes (beans and peas) can fix the nitrogen in the soil. So, instead of buying expensive fertilizers, you can add nutrients back into the soil by planting these next to other high nitrogen-consuming plants like corn. 

Leafy greens are also great at keeping soil covered, which can maintain the moisture levels in the soil for longer. 

Disease Management

Skip the pesticides and opt for an all-organic pest deterrent. Garlic, onions, and chives, when planted near tomatoes and carrots, can repel insects that cause infestations and diseases. These plants can also boost other defenses by providing a natural protective barrier from environmental stressors.  

Attracting Pollinators

Plants like marigolds and sunflowers bring in bees and butterflies, improving fruits and overall garden health. Place these plants next to high-yielding crops for an extra bountiful harvest.

Bonus Tip: Try planting nasturtiums near your vegetables—they not only attract pollinators, but attract aphids away from your crops, acting as a natural trap plant!

More Pro Tips for Tomato Companion Planting

If you want to grow the healthiest, most productive tomato plants, try these smart companion planting tips:

  • Make the Most of Your Space: Pair tall plants with low-growing ones to use every inch of your garden efficiently.

  • Mix It Up: Plant a variety of companions to help balance nutrients and keep pests under control.

  • Take Care of Your Soil: Rotate crops and add compost to keep your soil rich and healthy. Strong soil means strong plants that can fight off pests and diseases.

  • Use Herbs to Your Advantage: Basil and garlic not only improve flavor but also help keep bugs away. Other herbs can attract helpful pollinators and improve soil health.

Another Bonus Tip: Try planting marigolds around your tomatoes—they help repel pests and add a pop of color to your garden!

Final Thoughts

Companion planting is more than just a gardening strategy—it’s a way to cultivate a thriving and harmonious garden. By avoiding harmful tomato pairings and embracing beneficial ones, you’ll enjoy healthier plants, fewer pests, and better harvests. 

Whether you’re growing tomatoes for a summer salad or a pasta sauce, pairing them with the right plants will make all the difference! Be sure to check out all of our tomato varieties so you never miss out on that summer flavor.

 

Watch out for tomatoes biggest enemies here:

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