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🍅 13 Plants to Avoid Planting With Tomatoes This Season
Tomatoes are one of the most popular and rewarding crops in any home garden. They’re juicy, delicious, and versatile—but they’re also surprisingly picky about their neighbors. While many plants grow well alongside tomatoes (like basil, marigolds, and carrots), others can cause major problems—from stunted growth and reduced yield to rampant disease and pest infestations.
In this comprehensive guide, we’ll break down 13 plants you should never grow near tomatoes, explain exactly why they’re a bad match, and provide better companion alternatives. You’ll also find expert tips, garden layout strategies, and a detailed FAQ section to help you get the most out of your tomato patch this season.
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🌱 Why Plant Compatibility Matters for Tomatoes
Tomatoes are heavy feeders that are prone to fungal diseases and pest pressure. Their success depends on:
- Having enough nutrients and sunlight
- Strong airflow to prevent disease
- Minimal competition for space and water
- Growing with plants that don’t share pests or diseases
When incompatible plants are grown too close, tomatoes may suffer from:
- Blossom end rot
- Early blight
- Leaf curl
- Aphid and hornworm infestations
- Reduced fruit quality and size
That’s why strategic companion planting is so important—especially for tomatoes.
❌ 13 Plants to Avoid Planting With Tomatoes
Each plant listed below poses unique risks when grown too close to tomatoes. Let’s break them down, one by one.
1. Potatoes
Why to avoid:
Tomatoes and potatoes are both part of the nightshade family—and that’s exactly why they shouldn’t be neighbors. They’re susceptible to the same fungal diseases, especially early blight, late blight, and verticillium wilt. These soilborne diseases spread quickly between these crops and can devastate your harvest.
Better companion:
Plant basil, onions, or garlic near tomatoes instead. Move potatoes to a completely separate area of the garden, and rotate their location each season.
2. Corn
Why to avoid:
Corn attracts tomato fruitworms, which are the same as corn earworms—meaning pests can multiply and easily jump between crops. Corn also grows tall and casts shade, which tomatoes hate.
Better companion:
Try growing tomatoes near carrots, peppers, or nasturtiums instead. Keep corn in its own sun-filled row.
3. Fennel
Why to avoid:
Fennel is allelopathic—meaning it releases chemicals into the soil that can inhibit the growth of other plants, especially tomatoes. It’s notorious for stunting nearby crops.
Better companion:
Grow fennel in containers, well away from tomatoes. If you want feathery foliage near tomatoes, opt for dill (in moderation—more on that later).
4. Cabbage and Brassicas (Broccoli, Cauliflower, Kale, Brussels Sprouts)
Why to avoid:
These cool-weather brassicas compete aggressively with tomatoes for nutrients, especially nitrogen. They also prefer different conditions (cool temps and acidic soil), making them incompatible growing partners.
Better companion:
Instead, grow leafy greens like lettuce or spinach, which don’t hog nutrients and help suppress weeds.
5. Eggplant
Why to avoid:
Eggplant is another nightshade crop, which means it shares many of the same pests and diseases. Growing these two together increases your risk of blight, verticillium wilt, spider mites, and hornworms.
Better companion:
Keep eggplants in a different bed. Use marigolds or calendula as a barrier plant between eggplant and tomatoes.
6. Peppers (Bell or Hot)
Why to avoid:
Although commonly grown together, peppers and tomatoes are a risky combination. They’re both heavy feeders and nightshades that attract the same pests: whiteflies, thrips, and aphids.
Better companion:
Instead of planting side-by-side, try growing peppers in nearby but separate containers. Use basil or allium plants as a buffer.
7. Walnut Trees (Black or English)
Why to avoid:
Black walnut trees release juglone, a natural toxin that’s extremely harmful to tomatoes. Juglone inhibits growth and can lead to sudden wilting or death in tomato plants.
Better companion:
If you must garden near a walnut tree, grow tomatoes in raised beds with root barriers or containers.
8. Dill (Mature Plants)
Why to avoid:
While young dill can be a good companion, mature dill inhibits tomato growth by altering soil chemistry and competing for space. It can also attract tomato hornworms in late summer.
Better companion:
Plant young dill early in the season and remove it before flowering. Replace it with borage or calendula to support pollinators and fruit development.
9. Cucumbers
Why to avoid:
Tomatoes and cucumbers don’t get along well due to similar nutrient demands, water needs, and disease risks (especially powdery mildew and blight). When planted too close, both crops may underperform.
Better companion:
Grow cucumbers near beans or peas instead. Pair tomatoes with oregano, nasturtiums, or bush beans.
10. Carrots (In Excess)
Why to avoid:
Carrots are often listed as tomato companions, and in small numbers, they’re fine. But too many can compete with tomato roots for space, especially in raised beds.
Better companion:
Interplant a few carrots at the base of tomato plants—but avoid large patches. Opt for radishes or lettuce for underplanting instead.
11. Kohlrabi
Why to avoid:
Kohlrabi belongs to the brassica family and competes for space, water, and nutrients. It can crowd tomato roots and attract similar root pests like cutworms.
Better companion:
Instead of kohlrabi, grow bush beans or chives alongside tomatoes to promote nitrogen availability and repel pests.
12. Strawberries
Why to avoid:
Strawberries and tomatoes are both vulnerable to verticillium wilt, a devastating fungal disease. They also share pests like spider mites, making them high-risk neighbors.
Better companion:
Keep strawberries in their own bed or container. Grow tomatoes near garlic, onions, or asparagus instead.
13. Okra
Why to avoid:
Okra attracts nematodes, which are microscopic worms that damage tomato roots and reduce yields. Okra also grows tall and shades tomatoes if not pruned.
Better companion:
Grow okra near melons or corn, not tomatoes. Use sunflowers or alyssum to draw pollinators toward your tomato plants.
🌼 Plants That Love Growing With Tomatoes
To balance the list, here are a few plants that make excellent companions for tomatoes:
| Companion Plant | Benefits |
|---|---|
| Basil | Repels tomato hornworms and whiteflies; may improve tomato flavor |
| Marigolds | Repel nematodes, aphids, and whiteflies |
| Borage | Attracts pollinators; deters tomato hornworms |
| Garlic & Onions | Repel pests; improve soil health |
| Carrots (sparingly) | Help break up soil; improve airflow |
| Chives | Deter aphids and boost disease resistance |
| Nasturtiums | Trap crop for aphids and whiteflies |
| Spinach & Lettuce | Make excellent underplantings; suppress weeds |
🧑🌾 Expert Tomato Growing Tips
To maximize your tomato harvest, keep these best practices in mind:
✅ Choose the Right Location
Tomatoes love full sun, well-drained soil, and plenty of space.
✅ Use Crop Rotation
Don’t plant tomatoes in the same spot more than once every 2–3 years to prevent soil-borne diseases.
✅ Stake or Cage Plants Early
Support tall varieties from the start to prevent sprawling and reduce the risk of fungal disease.
✅ Water Consistently
Water deeply and evenly. Inconsistent watering leads to blossom end rot.
✅ Mulch Generously
Use straw or compost mulch to retain moisture, suppress weeds, and reduce soil splash (a major cause of disease).
Table of Contents
❓ FAQ: Companion Planting With Tomatoes
Q1: Can I grow peppers and tomatoes together?
While it’s common, it’s risky. Both are nightshades that share pests and diseases, making problems more likely. If you do plant them together, rotate often and monitor carefully.
Q2: Is basil really a good tomato companion?
Yes! Basil repels harmful insects like aphids and hornworms and may even improve the flavor of your tomatoes.
Q3: How far should I plant incompatible crops from tomatoes?
Keep conflicting plants at least 4–6 feet away, preferably in separate garden beds. For disease-prone combos like potatoes or strawberries, increase the distance to 10+ feet or more.
Q4: Can I grow tomatoes and cucumbers in the same raised bed?
It’s possible, but not ideal. If you must, use vertical trellising, maximize spacing, and monitor for signs of mildew or nutrient deficiency.
Q5: What’s the worst plant to grow near tomatoes?
Potatoes are the top offender due to shared soil diseases like late blight and similar pest profiles.
Q6: Can I grow herbs like parsley and cilantro with tomatoes?
Yes, but plant them on the edges of the tomato bed. Cilantro bolts quickly in heat, so grow it as a cool-season companion.
Q7: Is it true marigolds help tomatoes?
Absolutely. Marigolds deter many tomato pests, especially nematodes and aphids. Plant them around the perimeter of your tomato bed for best results.
🌿 Final Thoughts: Smart Tomato Plant Pairing Is the Key to a Healthy Garden
Tomatoes are one of the most rewarding crops you can grow, but they’re also high-maintenance. Knowing which plants to avoid is just as important as choosing good companions.
To recap:
- Avoid plants like potatoes, fennel, corn, and strawberries—they invite disease or pest issues.
- Use smart garden design—crop rotation, spacing, and mulching are crucial.
- Lean on friendly companions like basil, marigold, garlic, and borage to support tomato health naturally.
By planting thoughtfully this season, you’ll enjoy a stronger, more resilient tomato crop—and a more harmonious garden overall.
