Introduction
Tomatoes are among the most popular vegetables grown in home gardens, prized for their versatility, flavor, and ease of growth. However, growing healthy and productive tomato plants requires more than just good soil, water, and sunlight. Companion planting—the strategic positioning of plants that benefit each other—plays a crucial role in a thriving garden. When done correctly, it can improve yields, reduce pests, and boost the overall health of your garden. But not all plants are good companions, and some can cause significant harm to your tomato crop.
In this article, we’ll explore the concept of companion planting and specifically focus on seven plants that should never be grown near tomatoes. Understanding these negative plant relationships will help you create a more harmonious and productive garden, allowing your tomatoes to flourish without interference from harmful neighbors.
The Importance of Companion Planting
Companion planting is a traditional gardening technique in which plants are paired together based on their compatibility. Some plants improve the soil quality, others repel pests, and some even enhance the flavor of nearby crops. However, just as some plants benefit each other, others can create a toxic environment, stunting growth, attracting pests, or spreading diseases. Knowing which plants to avoid near tomatoes can make the difference between a bountiful harvest and a disappointing season.
Tomatoes are heavy feeders and require lots of nutrients, sunlight, and water to thrive. They also attract a range of pests and diseases, making them particularly vulnerable to poor plant pairings. Let’s dive into the seven plants that should never be grown near your beloved tomatoes.
1. Corn
One of the worst companions for tomatoes is corn. Both plants are highly susceptible to a common pest known as the corn earworm (Helicoverpa zea), also called the tomato fruitworm. This pest attacks both crops, making it more likely for an infestation to spread if the two are planted together.
Additionally, both corn and tomatoes are heavy feeders, competing for nutrients in the soil. Growing them close together can deplete the soil’s essential nutrients like nitrogen and potassium, leading to weaker plants and reduced yields.
Why Avoid Corn Near Tomatoes?
- Attracts the same pests (corn earworms/tomato fruitworms)
- Competes for nutrients, stunting the growth of both plants
Alternative: Consider planting beans or peas near your corn, as they can help fix nitrogen in the soil, benefiting both crops.
2. Potatoes
Potatoes and tomatoes both belong to the nightshade family (Solanaceae), and while this might make them seem like natural companions, they are not. The biggest issue with planting potatoes near tomatoes is their shared susceptibility to late blight, a fungal disease that thrives in humid conditions and can devastate both crops.
Once blight infects one plant, it can quickly spread through the soil and air to neighboring plants. Potatoes can also suffer from other fungal diseases that can transfer to tomatoes. Furthermore, potatoes compete with tomatoes for nutrients, making them poor companions.
Why Avoid Potatoes Near Tomatoes?
- Susceptibility to late blight, a fungal disease that spreads easily between them
- Competes for soil nutrients
Alternative: Instead of planting potatoes near tomatoes, try growing them with beans or peas, which help improve soil fertility.
3. Fennel
Fennel is notorious for being a bad companion plant in general, and tomatoes are no exception. Fennel releases a compound into the soil that can inhibit the growth of many plants, including tomatoes. This allelopathic effect prevents tomatoes from absorbing nutrients and growing to their full potential.
While fennel may attract beneficial insects that help with pollination, it is better grown in a separate part of the garden, away from most vegetables.
Why Avoid Fennel Near Tomatoes?
- Releases allelopathic chemicals that stunt tomato growth
- Competes for nutrients in the soil
Alternative: Instead of fennel, plant basil near your tomatoes. Basil not only enhances the flavor of tomatoes but also repels harmful pests like aphids and whiteflies.
4. Brassicas (Cabbage Family)
The cabbage family, which includes crops like broccoli, cauliflower, kale, and cabbage, is another group of plants that should not be grown near tomatoes. Brassicas are heavy feeders, just like tomatoes, and they compete for the same nutrients, which can lead to stunted growth for both types of plants.
Moreover, Brassicas are known to be “bad neighbors” for many plants, as they tend to dominate the garden space, potentially crowding out tomatoes and preventing them from receiving enough sunlight and nutrients.
Why Avoid Brassicas Near Tomatoes?
- Competes for nutrients, leading to stunted growth
- Can crowd out tomatoes, preventing proper growth and sunlight exposure
Alternative: Instead of Brassicas, try planting marigolds near tomatoes. Marigolds are excellent companion plants as they deter pests like nematodes and attract beneficial insects.
5. Eggplant
Eggplant, like potatoes, is a member of the nightshade family, and while these crops may seem related enough to grow together, they share many of the same pests and diseases. Both tomatoes and eggplants are susceptible to common pests like aphids, spider mites, and flea beetles. Growing them together can make it easier for these pests to travel between plants, leading to infestations.
Additionally, eggplants are prone to similar diseases as tomatoes, including fungal infections like blight and bacterial wilt. These diseases can spread quickly, damaging both crops.
Why Avoid Eggplant Near Tomatoes?
- Shares common pests and diseases with tomatoes, increasing the risk of infestations
- Competes for nutrients
Alternative: Grow eggplants in a separate area of the garden, away from other nightshade plants. Instead, plant herbs like parsley or chives near your tomatoes to improve their growth and deter pests.
6. Walnuts
Walnut trees, particularly black walnut, produce a chemical called juglone, which is toxic to many plants, including tomatoes. The roots, leaves, and even decomposing walnut tree materials release juglone into the soil, which can cause tomatoes to wilt and die if planted too close.
Even if the walnut tree is at a distance, its roots can extend far, spreading the toxic chemical to nearby garden beds. It’s best to avoid planting tomatoes anywhere near walnut trees to prevent exposure to juglone.
Why Avoid Walnuts Near Tomatoes?
- Releases juglone, which is toxic to tomatoes
- Can cause wilting and plant death if exposed to juglone
Alternative: Keep walnut trees far from your vegetable garden. If space is an issue, consider using raised beds or containers to grow your tomatoes at a safe distance.
7. Peppers
Peppers, like tomatoes and eggplants, belong to the nightshade family and share many of the same pests and diseases. One of the main concerns with planting peppers near tomatoes is their susceptibility to bacterial spot, a disease that causes lesions on the fruit and leaves of both plants.
Growing peppers and tomatoes together can also lead to cross-infection of other diseases, such as verticillium wilt, which can linger in the soil and affect future crops. To reduce the risk of disease, it’s better to separate these nightshades in the garden.
Why Avoid Peppers Near Tomatoes?
- Susceptible to the same diseases, such as bacterial spot and verticillium wilt
- Attracts the same pests, increasing the chance of infestations
Alternative: Instead of planting peppers next to tomatoes, grow them with carrots or onions, which make excellent companions for both plants.
Conclusion
Tomatoes are a rewarding and relatively easy crop to grow, but companion planting is essential for their success. By avoiding certain plants that compete for nutrients, attract pests, or spread diseases, you can create a healthier environment for your tomatoes to thrive. Understanding the dynamics of plant relationships will not only improve your tomato yields but also contribute to the overall health of your garden.
Choose your companions wisely, and your tomatoes will thank you with a delicious, bountiful harvest!