Companion Planting: What to Grow with Tomatoes – The Ultimate UK Guide
Introduction
Tomatoes are a staple in UK gardens, grown in greenhouses, patios, and allotments for their juicy fruits and versatile uses. But did you know that what you grow next to your tomatoes can directly affect their health, flavour, and yield?
That’s where companion planting comes in. This time-tested gardening technique pairs plants that benefit each other—improving pollination, deterring pests, enhancing growth, and even saving space. In this complete UK-based guide, we explore the best plants to grow with tomatoes (and which to avoid) so you can enjoy a more productive, resilient tomato patch.
What is Companion Planting?
Companion planting is the practice of growing different plant species close together to:
- Deter pests naturally
- Attract pollinators and beneficial insects
- Improve soil health and fertility
- Provide support or shade
- Maximise growing space in beds or containers
For tomatoes, choosing the right companions can lead to healthier plants, fewer pests, and tastier fruit.
Best Companion Plants for Tomatoes
🌿 1. Basil
Why it helps:
- Repels aphids, whiteflies, and mosquitoes
- Enhances tomato flavour
- Attracts pollinators and hoverflies
How to plant it:
- Grow 1–2 basil plants per tomato in the same bed or container
- Pinch regularly to prevent flowering and encourage growth
🧄 2. Garlic and Chives
Why they help:
- Natural pest deterrents
- Help repel red spider mites and aphids
- Chives attract pollinators with edible flowers
How to plant:
- Space around tomato edges or between plants
- Don’t overcrowd—allow airflow
🌼 3. Marigolds (Tagetes)
Why they help:
- Deter nematodes and whiteflies
- Attract hoverflies and parasitic wasps
- Provide vibrant colour to your beds
Best types:
- French marigolds are most effective against pests
- Avoid tall varieties that may shade tomatoes
🐝 4. Borage
Why it helps:
- Attracts bees and beneficial insects
- Improves pollination
- Said to strengthen plant resistance and deter tomato hornworms
Planting tip:
- Allow space—borage can get bushy
- Use in borders near tomato beds
🌱 5. Nasturtiums
Why they help:
- Act as a trap crop—draw aphids away from tomatoes
- Attract pollinators and hoverflies
- Edible leaves and flowers for salads
Where to plant:
- Along edges of beds or pots
- Let them trail near greenhouse tomatoes
🌿 6. Parsley
Why it helps:
- Attracts hoverflies and parasitic wasps
- Beneficial for pollination and pest control
- Doesn’t compete for space
Best use:
- Grow in pots near greenhouse or patio tomatoes
🌾 7. Lettuce and Spinach
Why they help:
- Quick-growing ground cover to shade soil
- Helps retain moisture and reduce weeds
- Doesn’t compete with tomatoes for root space
Where to plant:
- In between or beneath tomato plants
- Harvest regularly to avoid overcrowding
🥕 8. Carrots
Why they help:
- Loosen soil around tomatoes
- Minimal competition as roots grow at different levels
Tip:
- Thin carrots well to avoid dense clumps under tomatoes
🌸 9. Calendula (Pot Marigold)
Why it helps:
- Attracts hoverflies and beneficial insects
- Offers edible petals and visual appeal
- Helps deter aphids
Planting tip:
- Ideal for planting in corners or along greenhouse edges
🌿 10. Coriander (Cilantro)
Why it helps:
- Attracts lacewings and hoverflies
- Helps control aphids and spider mites
Best use:
- Grow a few plants near tomato beds but allow space for airflow
Companion Planting Tomatoes in Containers
Even if you’re growing tomatoes in pots or grow bags, you can still companion plant effectively:
| Tomato Pot Companion | Pot Size Needed | Notes |
|---|---|---|
| Basil | 30cm shared pot | Clip regularly to prevent crowding |
| Chives | 20cm side pot | Good in corners of grow bags |
| Nasturtiums | Hanging pot nearby | Let them trail alongside |
| Lettuce | Edge of large trough | Harvest often |
Plants to Avoid Growing Near Tomatoes
Not all plants make good neighbours! Avoid these poor companions:
| Plant | Why to Avoid |
|---|---|
| Potatoes | Share the same pests and diseases (e.g. blight) |
| Corn | Attracts tomato hornworm and competes for light |
| Fennel | Releases compounds that inhibit tomato growth |
| Cabbage family (brassicas) | Compete for nutrients, attract root pests |
| Dill | Young dill helps, but mature dill stunts tomatoes |
Tip: Keep solanaceae crops (tomatoes, peppers, aubergines, potatoes) spaced well apart and rotate annually to avoid disease build-up.
Tips for Successful Tomato Companion Planting
✅ Mix heights and textures:
Pair tall tomatoes with low-growing herbs and flowers for a layered, space-saving effect.
✅ Encourage airflow:
Don’t overcrowd—good airflow prevents fungal diseases like blight and mildew.
✅ Use containers smartly:
If limited on space, use hanging baskets, troughs, and small pots to companion plant around tomatoes.
✅ Rotate crops annually:
Even companion plants should be rotated to keep soil healthy and pest cycles broken.
✅ Grow flowers nearby:
Encouraging pollinators increases fruit set—especially in greenhouse tomatoes.
Companion Planting for Greenhouse Tomatoes
Greenhouse-grown tomatoes still benefit from companionship, even in a controlled space.
Great greenhouse companions:
- Basil (potted)
- Marigolds (in corners)
- Chives and parsley (small pots)
- Nasturtiums (trailing from hanging baskets)
- Calendula (low light tolerant)
Tip: Grow pollinator-attracting plants near greenhouse doors or vents to encourage bees in.
Conclusion
Companion planting with tomatoes is one of the simplest ways to improve your garden’s productivity, naturally deter pests, and enjoy healthier, more flavourful fruits. Whether you’re growing in a greenhouse, on a patio, or in an allotment bed, choosing the right plant neighbours makes all the difference.
By pairing your tomatoes with supportive herbs, flowers, and leafy veg—and steering clear of harmful companions—you’ll create a vibrant, balanced, and beautiful tomato-growing environment all season long.
Top 10 Questions and Answers About Companion Planting with Tomatoes
1. What is the best companion plant for tomatoes?
Basil is a top choice—it improves flavour and repels pests.
2. Can I grow tomatoes and potatoes together?
No—both are prone to blight and should be grown separately.
3. Do marigolds really help tomatoes?
Yes! French marigolds repel whiteflies and nematodes, making them excellent companions.
4. Can I grow herbs with tomatoes in the same pot?
Yes—basil, chives, and parsley grow well alongside tomatoes in large containers.
5. Is companion planting just about pest control?
No—it also supports pollination, soil health, and space-saving designs.
6. Can I companion plant in a greenhouse?
Absolutely—use potted herbs and flowers to enhance your indoor tomato growing.
7. What plants should I avoid near tomatoes?
Avoid potatoes, corn, fennel, and mature dill—they cause problems with growth and pests.
8. Will companion planting reduce the need for chemicals?
Yes—many companion plants act as natural deterrents to common pests.
9. Can I companion plant in grow bags?
Yes! Add basil, chives, or lettuce in the sides or in small pots around the bag.
10. How close should companion plants be to tomatoes?
Within 30–60cm, depending on plant size—close enough to help, but far enough to allow airflow.