Compatibility
67% Mixed
Plants
3 selected
Pairs
3 analyzed
Basil repels aphids and whiteflies from tomatoes and may improve flavor
Plant within 18 in
Carrots loosen soil for tomato roots; tomatoes provide light shade for carrots
Plant within 2–3 rows
No strong interaction documented between these plants
Standard spacing applies
| Pair | Type | Spacing |
|---|---|---|
| Tomato + Basil | Plant within 18 in | |
| Tomato + Carrot | Plant within 2–3 rows | |
| Basil + Carrot | Standard spacing applies |
Inputs
Result
The Three Sisters is one of the most famous companion planting combinations. All three plants benefit each other with zero antagonistic pairings.
Inputs
Result
This is an excellent combination for a tomato-focused garden. Basil and marigolds provide double pest protection, while carrots improve soil structure.
Inputs
Result
This combination has three antagonistic pairings. Fennel should be isolated from nearly all vegetables, and tomatoes and potatoes share disease susceptibility.
Companion planting is the practice of growing certain plants together for mutual benefit. Plants can repel pests, attract pollinators, fix nitrogen in soil, provide physical support, or improve flavor. The benefits are well-documented across centuries of agricultural practice.
| Benefit Type | Example Pair | How It Works |
|---|---|---|
| Pest Deterrent | Tomato + Basil | Basil repels aphids and whiteflies |
| Nitrogen Fixing | Beans + Corn | Beans add nitrogen corn needs |
| Trap Cropping | Roses + Nasturtium | Nasturtiums lure aphids away |
| Physical Support | Corn + Beans | Corn stalks support bean vines |
The Three Sisters is a Native American companion planting technique that grows corn, beans, and squash together. Corn provides a trellis for beans, beans fix nitrogen that feeds corn and squash, and squash leaves shade the soil to retain moisture and deter weeds.
| Plant | Role | Spacing |
|---|---|---|
| Corn | Structural support for beans | 12 in apart in blocks |
| Beans | Nitrogen fixer for soil | 4–6 in from corn stalks |
| Squash | Ground cover, weed suppression | 24–36 in apart |
Fennel is the worst companion for tomatoes because it releases chemicals that inhibit tomato growth. Brassicas (broccoli, cabbage, cauliflower) compete for the same nutrients. Potatoes share susceptibility to blight and should be kept at least 3 rows apart.
| Bad Pairing | Problem | Minimum Distance |
|---|---|---|
| Tomato + Fennel | Growth inhibition chemicals | 4+ rows apart |
| Tomato + Brassicas | Nutrient competition | 3+ rows apart |
| Tomato + Potato | Shared blight disease | 3+ rows apart |
Companion plants should be within 2 to 3 rows of each other to maximize benefits. Pest-repelling herbs like basil work best within 2 feet of the target plant. Antagonistic plants should be separated by at least 3 rows or 4 feet to prevent negative interactions.
Yes, marigolds are one of the most effective companion plants. French marigolds release alpha-terthienyl from their roots, which kills root-knot nematodes. They also repel whiteflies, aphids, and tomato hornworms. Plant them as borders around vegetable beds for best results.
Peppers grow best with basil, carrots, onions, and tomatoes. Basil repels aphids and spider mites while improving pepper flavor. Carrots loosen the soil for pepper roots. Avoid planting peppers near fennel or brassicas, which compete for nutrients.
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Last Updated: Mar 9, 2026
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