When deciding what not to plant next to your tomatoes, focus on avoiding plants that compete for the same nutrients, attract the same pests, or harbor diseases that tomatoes are susceptible to. Strategic companion planting can significantly boost your tomato harvest and health.

What Not to Plant Next to Tomatoes: A Gardener’s Guide

Growing delicious, juicy tomatoes is a summertime goal for many home gardeners. However, the success of your tomato plants often depends on what you choose to grow alongside them. Certain plants can hinder tomato growth, attract unwanted pests, or spread diseases. Understanding these plant relationships is key to a thriving vegetable patch.

Why Companion Planting Matters for Tomatoes

Tomatoes, a member of the nightshade family, have specific needs and vulnerabilities. Companion planting, the practice of growing different crops in proximity to each other, can offer benefits like pest deterrence, nutrient sharing, and improved growth. Conversely, poor companion choices can lead to nutrient depletion, increased pest pressure, and a higher risk of diseases like blight.

Avoiding Nutrient Competition

Tomatoes are heavy feeders, meaning they require a substantial amount of nutrients from the soil to produce abundant fruit. Planting other nutrient-hungry vegetables nearby can lead to competition, resulting in smaller, less flavorful tomatoes. It’s best to give your tomatoes ample access to the soil’s resources.

Pest and Disease Prevention

Some plants can attract pests that also target tomatoes, such as aphids, whiteflies, and hornworms. Others may carry diseases that can easily spread to your tomato plants. Choosing companions that repel these pests or are resistant to common tomato ailments is a smart strategy.

The "Don’t Plant These" List for Tomatoes

Certain plants are consistently advised against planting near tomatoes. These are typically other members of the nightshade family, as they share similar pest and disease issues. Additionally, some root vegetables and brassicas can negatively impact tomato growth.

Brassicas (Cabbage Family)

• Broccoli, Cauliflower, Cabbage, Kale, Brussels Sprouts: These vegetables are heavy feeders and can deplete the soil of nutrients that tomatoes need. They also tend to stunt the growth of nearby tomato plants. Their different nutrient requirements can create an imbalance in the soil.

Other Nightshades

• Potatoes: Potatoes are also nightshades and are highly susceptible to late blight, a devastating disease that can quickly spread to tomatoes. Planting them together significantly increases the risk of this fungal infection. They also compete for similar nutrients.
• Eggplant: While closely related, eggplant can also attract similar pests and diseases as tomatoes, making them a risky companion. They share vulnerabilities to pests like flea beetles and Colorado potato beetles.
• Peppers: Similar to eggplant, peppers can attract the same pests and diseases that plague tomatoes. This close relationship increases the likelihood of shared problems.

Legumes (Certain Types)

• Fennel: Fennel is known to inhibit the growth of many plants, including tomatoes. It releases certain compounds into the soil that can be detrimental to tomato development. It’s best to give fennel its own space.

Corn

• Corn can attract the corn earworm, which is also a significant pest for tomatoes. Planting them together creates a buffet for this damaging insect. This shared pest can decimate both crops.

What About Root Vegetables?

While not as detrimental as other nightshades, some root vegetables can also pose challenges. They can compete for root space and may have different soil pH preferences.

• Carrots: Carrots and tomatoes have different soil needs. Tomatoes prefer a slightly acidic to neutral pH, while carrots can tolerate a wider range. Their root systems can also compete underground.

Strategic Companion Planting for Tomatoes

Now that you know what to avoid, let’s briefly touch on what does work well. Good companions for tomatoes include:

• Basil: Repels tomato hornworms and whiteflies.
• Marigolds: Deter nematodes and other soil-borne pests.
• Carrots: While some sources advise against it, many gardeners find carrots to be acceptable companions, especially if given ample space.
• Onions and Garlic: Repel a variety of pests with their strong scent.
• Borage: Attracts beneficial pollinators and deters tomato hornworms.

Common Mistakes to Avoid

Many gardeners make the mistake of planting tomatoes too close to their relatives in the nightshade family. This is a common cause of widespread disease in home gardens. Another error is overcrowding, which limits air circulation and nutrient availability for all plants.

Frequently Asked Questions (PAA)

Why shouldn’t I plant tomatoes and potatoes together?

Tomatoes and potatoes are both members of the nightshade family and share susceptibility to diseases like late blight. Planting them in close proximity significantly increases the risk of this devastating fungal disease spreading between the two crops. They also compete for similar nutrients in the soil.

Can I plant peppers near my tomatoes?

It’s generally best to avoid planting peppers too close to tomatoes. Both are nightshades and can attract the same pests, such as aphids and flea beetles, and are vulnerable to similar diseases. This shared vulnerability makes them poor companions.

Is it okay to plant basil next to tomatoes?

Yes, basil is an excellent companion plant for tomatoes! It’s believed to repel pests like tomato hornworms and whiteflies, and some gardeners swear it improves the flavor of tomatoes. Their needs are generally compatible.

What about planting corn and tomatoes together?

Planting corn and tomatoes together is generally not recommended. Corn is a magnet for the corn earworm, a pest that also readily attacks tomato plants. This proximity creates an ideal feeding ground for the earworm, potentially leading to significant damage to both crops.

Can I plant broccoli near my tomatoes?

No, it’s advisable to keep broccoli and other brassicas away from your tomatoes. These plants are heavy feeders and can compete aggressively for nutrients in the soil, potentially stunting your tomato plants’ growth. They also have different soil pH preferences.

Next Steps for a Bountiful Harvest

By understanding these planting relationships, you can create a more harmonious and productive garden. Consider planning your garden layout carefully, giving your tomatoes the space and companions they need to thrive.

Ready to plan your garden? Explore our guide on choosing the best soil amendments for tomatoes to further boost your harvest!