Tomato Companion Plants: 14 Best Choices + Bed Layout

The best tomato companion plants include basil, marigolds, nasturtiums, sweet alyssum, calendula, chives, onions, garlic, dill, coriander, parsley, borage, yarrow, and chamomile.

These plants can help you create a more diverse tomato bed, attract pollinators and beneficial insects, fill unused growing space, cover exposed soil, or give you an additional edible harvest.

However, companion planting is not a magical pest shield.

One basil plant will not make every aphid disappear. Marigolds do not automatically protect tomatoes from every soil pest. Nasturtiums only work as a trap crop when pests actually prefer them and you monitor the plants regularly.

The most useful approach is to choose companion plants for a specific job, place them where they will not crowd your tomatoes, and continue checking the bed for pests, diseases, and watering problems.

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Grow More Tomatoes with These Companion Planting Hacks! [Video]

Do Tomato Companion Plants Really Work?

Companion planting can be useful, but many online claims are exaggerated.

There is a meaningful difference between these statements:

“This flower provides nectar and pollen for insects.”
“This flower may help support insects that feed on certain pests.”
“This flower prevents pests from attacking tomatoes.”

The first two can be reasonable. The third is usually far too certain.

What companion planting can do

A carefully planned mixed bed can:

• Provide flowers for pollinators and beneficial insects.
• Make better use of space around upright tomato plants.
• Produce herbs, flowers, leaves, or bulbs alongside the tomatoes.
• Cover some bare soil.
• Increase plant diversity.
• Create alternative habitat for insects.
• Make pest outbreaks easier to notice when you inspect regularly.

What companion planting cannot guarantee

Companion plants cannot reliably:

• Stop every aphid, whitefly, caterpillar, or mite.
• Cure tomato diseases.
• Replace proper spacing and ventilation.
• Correct poor soil or inconsistent watering.
• Prevent blight.
• Make an unhealthy tomato plant healthy.
• Guarantee a larger or better-tasting harvest.

Think of companion planting as one part of a healthy growing system, not as a replacement for basic tomato care.

Best Tomato Companion Plants at a Glance

Basil

Basil is one of the easiest plants to combine with tomatoes because both prefer warmth, sunlight, and reasonably consistent moisture.

Its clearest benefit is also the simplest: you can harvest tomatoes and basil from the same bed.

Basil is often claimed to make tomatoes taste better or repel large numbers of pests. Those claims are difficult to guarantee. Plant basil because it is useful, compact, edible, and well suited to similar growing conditions.

How to plant basil with tomatoes

• Leave approximately 20 to 30 centimetres between basil plants.
• Keep basil away from the immediate base of the tomato stem.
• Prune or harvest it regularly to prevent a dense mass of foliage.
• Remove flower heads if you want continued leaf production.
• Let selected plants flower when you want to provide insect habitat.

In containers, basil usually grows better in its own smaller pot placed beside the tomato. This prevents both plants from competing inside an undersized container.

Marigolds

Marigolds are useful as sunny border plants because they flower for a long period and fit easily around vegetable beds.

Their flowers can attract a range of visiting insects, but marigolds are frequently oversold as a complete pest-control solution.

Certain French marigold varieties can affect some root-knot nematodes in the soil immediately around their roots. That does not mean two decorative marigolds will clear an entire tomato bed of nematodes.

Where nematodes are a confirmed problem, resistant tomato varieties, crop rotation, soil testing, sanitation, and local professional advice are more dependable starting points.

How to use marigolds

• Plant them along the sunny outer edge.
• Leave enough space for air to move around the tomatoes.
• Remove faded flowers to encourage more blooms.
• Inspect the leaves for spider mites and other pests.
• Choose compact varieties for containers and small raised beds.

Nasturtiums

Nasturtiums produce edible leaves and flowers and can cover bare ground around a tomato bed.

They are also commonly used as a trap crop for aphids and some caterpillars. A trap crop is a plant grown because a pest may prefer it to the main crop.

However, planting a trap crop is not the end of the job.

You must inspect the nasturtiums. When aphids build up heavily, prune the affected section, wash the pests away, remove the plant, or manage the infestation before it spreads.

Nasturtiums Best placement

Plant nasturtiums along the outer edge of the tomato bed.

Trailing varieties can quickly grow through tomato stems, across paths, and up supports. Guide them away from the main tomato canopy before they make their own decisions.

In a greenhouse, keep nasturtiums under particularly close observation. Protected conditions can also help aphid colonies grow quickly.

Sweet Alyssum

Sweet alyssum is one of the most useful low-growing flowers for a vegetable bed.

Its many small flowers are accessible to hoverflies and other beneficial insects. Hoverfly larvae feed on aphids, although the level of pest control will depend on local insect populations and growing conditions.

Alyssum stays lower than many flowering companions, making it suitable for borders and raised-bed edges.

Sweet alyssum Planting tips

• Space plants approximately 15 to 25 centimetres apart.
• Use them along the front of the bed.
• Trim spreading plants when they block access or airflow.
• Keep some flowers available throughout the season.
• Do not let the plants completely cover the tomato root zone.

Alyssum works particularly well when combined with taller flowering plants so that the bed offers flowers at different heights.

Calendula

Calendula produces bright, accessible flowers over a long period.

It can be planted near tomatoes to increase flowering diversity and bring more insect activity into the area.

Calendula can also attract aphids. This is not always a failure. It may provide predators with a food source or function as a monitored decoy plant. It becomes a problem when the aphid population is ignored.

Grow calendula successfully

• Plant it near the edge where the leaves are easy to inspect.
• Remove badly infested flower stems when necessary.
• Deadhead regularly for a longer flowering period.
• Avoid letting large plants lean into tomato foliage.
• Allow selected flowers to set seed when you want new seedlings.

Chives

Chives fit neatly around tomatoes because they grow upright rather than spreading wide leaves across the soil.

The leaves provide an edible harvest, while mature clumps produce flowers that are visited by bees and other insects.

Their strong scent is sometimes said to confuse pests, but it should not be treated as guaranteed protection.

Where to plant chives

Place chives near the front or side of the tomato bed.

Remember that chives are perennial. A small plant can become a thick clump over time. Divide established plants before they begin crowding the bed.

Onions

Onions are useful companions where space is limited.

Their narrow leaves allow sunlight to reach nearby plants, and they can be fitted into gaps that would be too small for bushier herbs.

Onions are often promoted as pest repellents. Their scent may add diversity to the bed, but onions will not prevent every aphid, whitefly, or caterpillar from finding your tomatoes.

Use onions because they:

• Produce another edible crop.
• Take up relatively little horizontal space.
• Can be harvested before tomatoes reach maximum size.
• Fit along paths and raised-bed edges.
• Do not usually create dense shade.

Garlic

Garlic can share space with tomatoes during part of the growing season.

In many climates, garlic is already well developed by the time young tomatoes are transplanted. The garlic can then be harvested as the tomatoes begin filling the bed.

This makes garlic useful for seasonal space sharing, rather than because it acts as a permanent tomato protector.

Avoid damaging tomato roots when digging up mature garlic. Plant garlic in a separate strip or near an accessible edge.

Dill

Dill produces clusters of small flowers that can be visited by hoverflies, parasitic wasps, and other insects.

The main challenge is its size. Dill can become taller than expected, especially when grown in rich soil.

Plant it where it will not:

• Shade young tomatoes.
• block a greenhouse path.
• fall across tomato supports.
• create a dense patch of damp foliage.

Let selected dill plants flower, but remove unwanted seedlings before the entire bed becomes a dill nursery.

Coriander

Coriander gives you two useful stages.

First, you can harvest the leaves. Later, when the plant bolts, its small flowers can provide food for visiting insects.

Coriander often bolts quickly during warm weather. This is inconvenient when you want leaves, but useful when your goal is to produce flowers.

Sow small batches rather than filling the bed all at once. This gives you plants at different growth stages.

Parsley

Parsley is a compact edible plant that can fill open space near the front of a tomato bed.

Most parsley plants do not flower until their second growing season. First-year plants are therefore primarily an edible crop rather than an insectary plant.

Allowing a few plants to overwinter and flower the following year can add another source of small flowers.

Keep parsley low and harvested so it does not form a dense, humid clump beneath tomato foliage.

Borage

Borage produces blue flowers that are popular with bees and other pollinators.

It is often described as a tomato companion, but it is not a small plant. One mature borage can occupy far more space than several basil or alyssum plants.

For that reason, borage usually works better:

• At the end of a long tomato row.
• Outside a raised bed.
• Beside a greenhouse entrance.
• In a large container near the tomatoes.
• In a separate flowering strip.

Borage also self-seeds readily. Remove unwanted seedlings while they are still small.

Yarrow

Yarrow is a perennial flowering plant that can help create permanent habitat around a food-growing area.

It is better suited to the outside of the tomato bed than directly between tomato plants.

Yarrow can spread and compete for space. Plant it in a controlled border or container where its flowers remain close enough to benefit the wider garden without taking over the vegetable bed.

Chamomile

Chamomile is a compact flowering option for sunny edges and containers.

You can harvest the flower heads, while leaving enough blooms available for insects.

Chamomile is less likely to overpower a bed than borage or yarrow, although it can still self-seed. Thin unwanted seedlings and prevent the foliage from becoming too dense beneath the tomatoes.

How to Plan a Tomato Companion Bed

The best companion bed is not the one with the greatest number of plants.

It is the one that gives every plant enough light, root space, water, and airflow.

Step 1: Position the tomatoes first

Tomatoes are the main crop, so plan around their mature size.

Install stakes, strings, cages, or trellises when planting. Adding support later can damage roots and becomes much harder once surrounding companions have grown.

For most supported tomatoes, allow approximately 45 to 60 centimetres between plants. Large indeterminate varieties may need more room, depending on how they are trained.

Always follow the spacing guidance for your variety.

Step 2: Keep access routes open

Leave enough space to:

• Water at soil level.
• Tie stems to supports.
• Remove lower leaves.
• Inspect the undersides of leaves.
• Harvest ripe tomatoes.
• Remove diseased material.
• Reach trap crops before infestations spread.

Do not fill every visible patch of soil.

Step 3: Add compact edible plants

Place basil, parsley, chives, onions, or coriander in accessible gaps.

Do not plant them directly against the tomato stem. Keep a clear area around the base so you can water, inspect, and prune the plant.

Step 4: Add flowering borders

Use alyssum, calendula, chamomile, and compact marigolds around the outer section of the bed.

This provides flowers without creating a thick layer beneath the tomatoes.

Step 5: Place large plants outside the main row

Borage, tall dill, yarrow, and vigorous nasturtiums need more space.

Place them at bed ends, along external borders, or in nearby containers.

Step 6: Mulch the remaining open soil

You do not need a living plant in every gap.

A layer of suitable organic mulch can:

• Reduce soil splash.
• Slow moisture loss.
• Suppress some weeds.
• Keep low tomato leaves away from bare soil.
• Reduce competition compared with densely planted companions.

Keep mulch slightly away from the tomato stem.

Interactive Tomato Companion Plant Selector

Choose your growing space and your main goal. The selector will suggest companions.

Example Tomato Companion Bed Layout

For a raised bed measuring approximately 120 × 240 centimetres, you could use:

Centre or rear section

Three or four supported tomato plants.
Enough space between the tomato plants for pruning and harvesting.
Supports installed before the companion plants fill the bed.

Between widely spaced tomatoes

Two or three basil plants.
Small groups of onions or chives.
A small amount of parsley or coriander.

Front edge

Sweet alyssum.
Compact marigolds.
Chamomile.
Calendula.

Outer corners

One trailing nasturtium, guided away from the tomatoes.
Dill at a corner where it will not shade the bed.
Borage outside the bed rather than inside it.

This is only a starting point. Reduce the number of companion plants when using vigorous tomato varieties or growing in humid conditions.

When to Plant Tomato Companions

The correct timing depends on your climate and whether the plants are being grown outdoors, under cover, or in a heated greenhouse.

Before the tomatoes

These plants can often be established before tomato transplanting:

• Garlic
• Onions
• Chives
• Parsley
• Calendula
• Coriander
• Chamomile

Avoid damaging their roots when you later add tomato supports.

Around tomato transplanting time

Plant warmth-loving companions after frost risk has passed and conditions have warmed:

• Basil
• Nasturtiums
• Marigolds
• Sweet alyssum
• Borage

Basil is especially sensitive to cold conditions.

After the tomatoes are established

You can fill selected gaps with:

• Additional basil.
• Late coriander sowings.
• Small alyssum plants.
• Compact marigolds.
• Onions grown for young leaves.

Do not add more plants simply because the bed looks empty in spring. Tomato plants may become several times larger by midsummer.

Tomato Companion Plant Spacing

Treat these figures as practical starting points. Variety, pruning style, soil fertility, container size, and climate can all change the amount of space a plant needs.

Tomato Companion Plants in Pots

Container companion planting is often presented using photographs taken immediately after planting.

The arrangement may look attractive at first, but a mature tomato has a large root system and high water demand.

For most full-size tomato varieties, use a container holding at least 30 to 40 litres, with larger containers preferred for vigorous indeterminate plants.

Instead of filling the same pot with many companions, try this arrangement:

• One tomato in the main container.
• One compact basil near the outer edge only when the pot is sufficiently large.
• Alyssum or a small marigold in a separate nearby pot.
• Nasturtiums in a hanging basket or container where they can trail.
• Chives, parsley, and coriander in their own herb container.

Separate pots make watering and feeding easier. They also let you move flowering plants closer to or farther from the tomatoes as needed.

Tomato Companion Plants in a Greenhouse

Greenhouse conditions require a different approach from open-ground planting.

Humidity can remain high, particularly during cool nights and wet weather. Too many plants beneath the tomatoes can slow leaf drying and restrict airflow.

In our greenhouse in the Netherlands, we prioritise:

• Supported vertical tomato growth.
• Removing unnecessary lower tomato leaves.
• Watering at soil level.
• Keeping paths and ventilation openings clear.
• Pruning companions before they touch tomato foliage.
• Inspecting trap crops and flowers for aphids.
• Using nearby pots when the bed itself is becoming crowded.

Good greenhouse companions include compact basil, alyssum, chives, onions, coriander, and carefully managed marigolds.

Place large borage, yarrow, vigorous nasturtiums, and tall dill outside the main tomato row or in separate containers.

Soil, Watering, and Feeding

Companion plants still need compatible growing conditions.

Soil

Tomatoes grow best in fertile, well-drained soil with plenty of organic matter.

Do not repeatedly add fertiliser just because the bed contains more plants. Excessive nitrogen can produce large amounts of leafy growth while increasing crowding and delaying fruit development.

Use a soil test where possible and follow the fertiliser guidance for your tomato variety and growing system.

Watering

Water deeply at soil level rather than spraying the entire bed.

This helps keep tomato leaves dry and reduces unnecessary humidity around the plants.

Check moisture beneath the surface. A bed covered by companion plants may look moist while the tomato root zone is becoming dry.

Containers require particularly close attention because several plants can empty a pot quickly during hot weather.

Feeding

Tomatoes are generally heavier feeders than alyssum, chamomile, or Mediterranean-style flowering herbs.

Feed the tomatoes according to their stage of growth, but avoid soaking every companion plant with concentrated fertiliser when it is not needed.

A separate container can be the better choice when two plants have very different feeding or watering requirements.

Plants to Keep Away From Tomatoes

Many “bad companion plant” lists repeat claims without explaining whether the problem is disease, shade, root competition, or folklore.

Focus on practical conflicts.

Potatoes

Tomatoes and potatoes belong to the same plant family and can be affected by several of the same diseases, including early and late blight.

Growing them close together can also make crop rotation more difficult.

Give potatoes their own area and avoid repeatedly planting tomatoes, potatoes, peppers, or aubergines in the same soil without a sensible rotation plan.

Large, dense plants

Any crop can become a poor companion when it:

• Shades the tomato.
• Blocks airflow.
• makes watering difficult.
• hides pests.
• tangles around supports.
• competes heavily for root space.

This can include squash, vigorous pumpkins, large borage plants, tall flowering plants, or even too much basil.

Fennel

Fennel becomes large and can be difficult to fit into a tomato bed without causing competition.

It is frequently claimed that fennel chemically harms nearly every neighbouring vegetable, but the practical reason to separate it is simpler: it needs space and is easier to manage as its own crop.

Black walnut trees

Tomatoes are sensitive to juglone produced by black walnut trees.

Avoid planting tomatoes within the affected root zone or using fresh walnut leaves, roots, bark, or sawdust around the tomato bed.

Common Tomato Companion Planting Mistakes

Planting too densely

The most common mistake is treating every open patch of spring soil as unused space.

By midsummer, the tomatoes, basil, flowers, and nasturtiums may be touching. This reduces airflow and makes inspection difficult.

Fix: Remove, relocate, harvest, or prune companions before the canopy becomes congested.

Believing every pest-repellent claim

A strong-smelling herb does not create an invisible barrier around your tomatoes.

Fix: Continue checking leaves for aphids, whiteflies, mites, caterpillars, eggs, and feeding damage.

Ignoring trap crops

A nasturtium covered in aphids is not automatically protecting anything.

It may simply be producing more aphids.

Fix: Inspect trap crops frequently and manage infestations before winged aphids move to nearby plants.

Placing large plants in the centre

Borage, dill, yarrow, and trailing nasturtiums can overwhelm a small bed.

Fix: Move large companions to bed ends, borders, or containers.

Watering every plant in the same way

A mature tomato may need more water than a small flowering border plant.

Fix: Water according to root-zone moisture rather than giving every plant an identical amount.

Forgetting access

A bed can look beautiful but become impossible to prune or harvest.

Fix: Maintain a clear route to each tomato stem and support.

Depending on flowers that are not flowering

Young parsley, recently cut basil, and immature dill provide little nectar or pollen.

Fix: Combine plants with different flowering times and allow selected herbs to bloom.

Troubleshooting a Tomato Companion Bed

The bed feels crowded

Remove the least useful plants first.

Harvest basil heavily, move containers, prune trailing nasturtiums, and remove self-seeded flowers. Do not sacrifice tomato airflow to preserve every companion.

Aphids are covering the nasturtiums

Prune heavily infested growth or remove the plant. Check nearby tomatoes and flowers, especially the undersides of young leaves.

Avoid moving an aphid-covered plant through the entire bed.

Not sure which insect is attacking your plants? Upload a clear photo to the StrongEcho AI Pest Identifier.

Tomato leaves are turning yellow

Companion plants are rarely the only possible cause.

Yellow leaves can result from natural ageing, watering problems, nutrient issues, root stress, disease, or pest damage.

Start by checking:

• Which leaves are yellowing.
• Whether the soil is wet or dry.
• Whether symptoms affect one plant or several.
• Whether spots, holes, webbing, curling, or insects are present.
• Whether nearby companions are competing heavily.

You can upload a photo to the StrongEcho AI Plant Health Identifier for help examining visible symptoms.

Whiteflies appear in the greenhouse

Companion planting alone is unlikely to solve an established whitefly problem.

Inspect leaf undersides, remove heavily affected material where appropriate, manage weeds, improve ventilation, and use suitable monitoring or control methods for your location.

Use the StrongEcho AI Pest Identifier when you need help checking whether the insects are whiteflies or another small flying pest.

The tomatoes are growing slowly

Check the basics before blaming a neighbouring plant:

• Soil temperature.
• Night temperatures.
• Root-zone moisture.
• Available light.
• Container size.
• Soil fertility.
• Root damage.
• Pest or disease symptoms.

Cool spring conditions in the Netherlands can temporarily slow tomatoes and warmth-loving basil even when the planting arrangement is correct.

The companions are growing faster than the tomatoes

Cut them back early.

Companion plants should support the layout, not become the main canopy. Remove flowers or herbs that shade young tomatoes or interfere with their supports.

You do not recognise a volunteer plant

Do not assume every seedling near your tomatoes is a useful companion.

Upload a clear photo of the leaves and stem to the StrongEcho AI Plant Identifier before allowing it to occupy valuable root space.

A Simple Companion Combination for Beginners

Start with fewer plants rather than trying to use all 14 companions.

For two or three tomato plants, try:

• Two basil plants.
• A short row of chives or onions.
• Three compact marigolds.
• A strip of sweet alyssum.
• One nasturtium at the outer edge only when you can monitor it.

This gives you edible plants, flowers at different heights, and a manageable bed.

You can add coriander, calendula, dill, chamomile, or larger flowering plants once you know how much space your tomatoes use.

What We Have Learned at StrongEcho

We enjoy planting tomatoes as part of a mixed growing space rather than isolating every crop in a separate row.

The diversity makes the greenhouse more interesting, gives us additional herbs and edible flowers, and encourages us to inspect the bed more closely.

It has also taught us that more plants are not always better.

In humid conditions, the most useful “companion” may be an open patch of mulched soil that allows air to circulate beneath the tomatoes.

We grow more food than we need when possible, and part of our harvest is donated to local organisations.

That makes productive use of space important, but healthy plants come first. An overcrowded bed does not produce more usable food simply because it contains more plants.

Frequently Asked Questions

What is the best companion plant for tomatoes?

Basil is one of the easiest choices because it is edible, compact, and enjoys similar warm growing conditions. Sweet alyssum is a strong flowering option for bed edges, while chives and onions fit narrow gaps.

The best choice depends on whether your priority is food, flowers, ground cover, or a trap-crop experiment.

Can basil and tomatoes grow in the same pot?

They can share a sufficiently large container, but a full-size tomato has a large root system and high water demand.

In smaller containers, grow basil in a separate pot beside the tomato. This reduces competition and makes watering easier.

Do marigolds keep pests away from tomatoes?

Marigolds may contribute flowers, scent diversity, and habitat, but they do not guarantee pest-free tomatoes.

Certain French marigold varieties can affect specific root-knot nematodes close to their roots. This is much more limited than the common claim that any marigold protects an entire vegetable bed.

Do marigolds protect tomatoes from nematodes?

Only particular marigold varieties have shown useful effects against certain nematodes, and the effect occurs mainly in the immediate root zone.

Mass planting or using marigolds as part of a rotation is different from placing one ornamental marigold beside a tomato.

Are nasturtiums good companion plants for tomatoes?

Nasturtiums can provide edible flowers, ground cover, and a possible trap crop for aphids.

They need monitoring. Remove or prune heavily infested growth before pests spread, and guide trailing stems away from tomato supports.

Does basil improve the flavour of tomatoes?

There is no dependable reason to promise that growing basil nearby will change tomato flavour.

Tomato flavour is strongly influenced by variety, ripeness, sunlight, plant health, watering, and growing conditions. Grow basil nearby because the two crops are useful together in the garden and kitchen.

Which flowers grow well with tomatoes?

Useful flowering options include sweet alyssum, calendula, marigolds, chamomile, borage, yarrow, and flowering dill or coriander.

Choose a mixture of heights and flowering periods, but do not allow the flowers to restrict airflow around the tomatoes.

What should not be planted beside tomatoes?

Keep tomatoes away from potatoes where possible because they share several diseases and make rotation more difficult.

Also avoid placing tomatoes beneath black walnut trees or crowding them with large plants that create shade and poor airflow.

Can companion plants prevent tomato blight?

No. Companion plants cannot reliably prevent early or late blight.

Reduce disease risk by using healthy plants, rotating crops, mulching the soil, watering at ground level, providing adequate spacing, supporting plants, removing affected material, and keeping leaves as dry as practical.

Can I plant onions around tomatoes?

Yes. Onions use relatively little horizontal space and can fit along tomato-bed edges.

Their scent should not be treated as guaranteed pest control, but they provide an additional edible harvest without creating much shade.

What tomato companions work in a greenhouse?

Compact basil, sweet alyssum, chives, onions, coriander, parsley, and carefully managed marigolds work well.

Avoid filling the entire soil surface. Greenhouse tomatoes need airflow, easy access, and ventilation, especially in humid conditions.

How many companion plants should I put around one tomato?

There is no fixed number.

One tomato might share space with one basil plant and a few small border flowers. A heavily pruned greenhouse tomato may allow more ground-level planting than a large, unpruned bush variety.

Judge the arrangement by mature plant size, not by how empty the bed looks after transplanting.

Build a Healthier Tomato Bed

Choose companions for a clear reason.

Use basil and alliums for an additional edible harvest. Add alyssum, calendula, chamomile, or flowering herbs for floral diversity. Test nasturtiums as a trap crop only when you can monitor them. Keep large plants outside the main tomato canopy.

Most importantly, continue checking the tomatoes themselves.

When you find an unfamiliar plant, insect, damaged leaf, yellowing, curling, or unusual growth, use the appropriate StrongEcho tool:

• Identify an unknown plant with the AI Plant Identifier
• Check yellow leaves, spots, wilting, or poor growth with the AI Plant Health Identifier
• Identify insects, larvae, eggs, and feeding damage with the AI Pest Identifier

Start with a few useful companions, observe how they grow, and adjust the bed before it becomes crowded.

You can grow it.