Companion Planting Layout Guide: What to Plant Together

Strategic plant partnerships create healthier, more productive gardens

Have you ever noticed how some plants seem to thrive together while others struggle when placed side by side? This isn’t coincidence—it’s the ancient wisdom of companion planting at work.

For thousands of years, gardeners have observed that certain plant combinations create synergy: they repel pests, attract beneficial insects, improve soil health, or enhance each other’s growth. The Three Sisters method (corn, beans, squash) developed by Native Americans is perhaps the most famous example, but modern science has validated dozens of these traditional partnerships.

When I redesigned my vegetable garden using companion planting principles, the results were remarkable. My tomato plants, paired with basil and marigolds, had 70% fewer hornworm problems. My brassicas, interplanted with aromatic herbs, suffered minimal cabbage worm damage. And my yields increased across the board.

This comprehensive guide will show you exactly which plants belong together and which should stay apart, with practical layout suggestions you can implement immediately.

The Science Behind Companion Planting

How Companion Planting Works

Companion planting operates through several biological mechanisms:

Pest Confusion: Mixed plantings make it harder for pests to locate host plants by masking scent or visual cues.Trap Cropping: Sacrificial plants attract pests away from valuable crops.Beneficial Insect Attraction: Flowering companions provide nectar for predator insects that control pests.Soil Improvement: Some plants fix nitrogen, mine minerals, or create beneficial root zone environments.Physical Protection: Tall plants provide shade or windbreak for more delicate companions.Allelopathy: Some plants release chemicals that suppress weeds or inhibit specific pests.

Scientific Validation

Research has confirmed many traditional companion planting combinations:

Study Finding	Companion Pair	Effect
Iowa State University	Marigolds + tomatoes	70% reduction in root-knot nematodes
University of Florida	Basil + tomatoes	Reduced thrips and hornworms
Journal of Chemical Ecology	Nasturtiums + cabbage	Reduced aphid infestation
USDA Research	Buckwheat + vegetables	Increased beneficial insect populations

The Ultimate Companion Planting Chart

Tomatoes and Their Companions

Basil and tomatoes are classic companions in the garden and kitchen

Best Companions:

Companion	Benefit	Spacing
Basil	Repels flies, mosquitoes, hornworms; improves flavor	12-18 inches
Marigolds	Repels nematodes, whiteflies	12 inches
Parsley	Attracts beneficial insects	12 inches
Carrots	Loosens soil for tomato roots	6 inches
Onions	Repels aphids	6 inches
Chives	Deter aphids, improve flavor	8 inches
Spinach	Living mulch, uses different root zone	6 inches
Borage	Attracts pollinators, deters hornworms	12 inches
Nasturtiums	Trap crop for aphids	12 inches

Avoid Planting Near:

• Potatoes: Shared diseases (blight), compete for nutrients
• Fennel: Inhibits tomato growth through allelopathy
• Corn: Tomato fruit worm is also corn earworm
• Dill: Mature dill inhibits growth (young dill okay)

Recommended Tomato Companion Layout:

“` [Marigold] [Marigold] [Marigold] [Basil] [Tomato] [Basil] [Onion] [Carrot] [Onion] [Chive] [Parsley] [Chive] “`

Peppers and Eggplants (Nightshade Family)

Best Companions:

Companion	Benefit	Spacing
Basil	Repels aphids, spider mites, mosquitoes	12 inches
Onions	Repel aphids, slugs	6 inches
Spinach	Ground cover, different root zone	6 inches
Okra	Physical support, different pest profile	18 inches
Tomatoes	Similar care requirements	24 inches
Carrots	Soil improvement	6 inches
Petunias	Repel asparagus beetle, leafhoppers	12 inches
Oregano	General pest repellent	12 inches

Avoid Planting Near:

• Beans: Fix nitrogen peppers don’t need; may stunt peppers
• Brassicas: Compete for nutrients
• Fennel: Inhibits growth

Cucumbers and Squash (Cucurbits)

Best Companions:

Companion	Benefit	Spacing
Beans	Fix nitrogen, provide shade to roots	12 inches
Corn	Living trellis for vines	12 inches
Nasturtiums	Repel cucumber beetles, squash bugs	12 inches
Radishes	Repel cucumber beetles	3 inches
Oregano	General pest deterrent	12 inches
Sunflowers	Support vines, attract pollinators	18 inches
Tansy	Repels cucumber beetles, ants	18 inches
Dill	Attracts beneficial wasps	12 inches

Avoid Planting Near:

• Potatoes: Compete for water and nutrients
• Aromatic herbs (sage, rosemary): May inhibit growth
• Melons: Shared pests and diseases

Cucumber Beetle Defense Layout:

“` [Nasturtium] [Cucumber] [Nasturtium] [Radish] [Bean] [Radish] [Nasturtium] [Cucumber] [Nasturtium] “`

Brassicas (Cabbage, Broccoli, Kale, Cauliflower)

Best Companions:

Companion	Benefit	Spacing
Nasturtiums	Trap crop for aphids, whiteflies	12 inches
Onions	Repel cabbage maggot, aphids	6 inches
Garlic	Strong pest repellent	6 inches
Dill	Attracts beneficial wasps	12 inches
Mint	Repels cabbage moths	12 inches
Rosemary	Repels cabbage moths	12 inches
Sage	Repels cabbage moths, black flea beetles	12 inches
Thyme	Repels cabbage worms	8 inches
Chamomile	Improves flavor, attracts beneficials	12 inches
Celery	Mutual growth enhancement	12 inches
Beets	Different root zone, soil improvement	6 inches
Spinach	Uses different space, living mulch	6 inches

Avoid Planting Near:

• Strawberries: Compete for nutrients; shared pests
• Tomatoes: Different pH preferences; shared diseases
• Pole beans: Fix nitrogen brassicas don’t need
• Grapes: Incompatible root chemicals

Cabbage Moth Defense System:

“` [Sage] [Thyme] [Rosemary] [Sage]

[Onion] [Broccoli] [Garlic] [Broccoli] [Onion]

[Nasturtium] [Nasturtium] [Nasturtium] “`

Root Vegetables (Carrots, Beets, Radishes, Turnips)

Best Companions:

Companion	Benefit	Spacing
Onions	Mask carrot scent from carrot fly	3 inches
Leeks	Same benefits as onions	4 inches
Chives	Repel carrot rust fly	4 inches
Rosemary	Repels carrot fly	12 inches
Sage	Repels carrot fly	12 inches
Lettuce	Marks row, different harvest time	6 inches
Radishes	Loosen soil, mark carrot rows	2 inches
Bush beans	Fix nitrogen, different root depth	6 inches
Tomatoes	Provide shade in summer	18 inches

Carrot Fly Protection Layout:

“` [Chive] [Onion] [Carrot] [Onion] [Carrot] [Onion] [Chive] [Chive] [Leek] [Carrot] [Leek] [Carrot] [Leek] [Chive] [Chive] [Onion] [Carrot] [Onion] [Carrot] [Onion] [Chive]

[Sage]—————————[Rosemary] “`

Avoid Planting Near:

• Dill: Stunts carrot growth
• Parsnips: Shared pests (carrot fly)
• Potatoes: Compete for nutrients and space

Beans and Peas (Legumes)

Best Companions:

Companion	Benefit	Spacing
Corn	Natural trellis, shade for roots	12 inches
Cucumbers	Similar growing conditions	12 inches
Squash	Living mulch, weed suppression	36 inches
Carrots	Use space after bean harvest	6 inches
Summer savory	Improves bean growth, deters beetles	12 inches
Rosemary	Repels bean beetles	12 inches
Potatoes	Different pest profile	18 inches
Nasturtiums	Repel aphids	12 inches

Avoid Planting Near:

• Onions/garlic/chives: Inhibit bean growth
• Peppers: Fixed nitrogen peppers don’t need
• Sunflowers: Stunt bean growth (allelopathic)
• Fennel: Inhibits growth

Three Sisters Layout:

“` Traditional mound planting:

[Corn] [Bean] [Bean] [Bean] [Corn] [Bean] [Bean] [Bean] [Corn]

Plant squash between mounds “`

Alliums (Onions, Garlic, Leeks, Shallots)

Best Companions:

Companion	Benefit	Spacing
Carrots	Masked scent repels carrot fly	3 inches
Beets	Different root depths	4 inches
Lettuce	Uses different space, quick harvest	6 inches
Strawberries	Onions repel strawberry pests	6 inches
Tomatoes	Onions repel aphids	6 inches
Brassicas	Repel cabbage pests	6 inches
Chamomile	Improves onion flavor	12 inches
Summer savory	Improves onion growth	12 inches

Avoid Planting Near:

• Beans/peas: Inhibit legume growth
• Asparagus: Compete for nutrients
• Sage: Different growing conditions

Leafy Greens (Lettuce, Spinach, Chard)

Best Companions:

Companion	Benefit	Spacing
Radishes	Mark rows, quick harvest	3 inches
Carrots	Different harvest times	4 inches
Onions	Pest protection	4 inches
Strawberries	Living mulch for both	8 inches
Tall crops	Provide afternoon shade	18 inches
Beets	Similar conditions, different harvest	6 inches

Interplanting Strategy for Greens:

• Plant lettuce every 2 weeks for continuous harvest
• Use radish rows to mark lettuce plantings
• Plant heat-tolerant greens under tall crops for summer shade

Herbs and Their Companions

Herb	Good Companions	Repels
Basil	Tomatoes, peppers, asparagus	Flies, mosquitoes, thrips
Chives	Carrots, tomatoes, roses	Aphids, carrot fly
Cilantro	Spinach, lettuce	Spider mites
Dill	Brassicas, lettuce, onions	Aphids, spider mites
Lavender	Brassicas, fruit trees	Moths, fleas
Mint	Brassicas, tomatoes	Cabbage moths, ants
Oregano	Cucumbers, squash	Cucumber beetles
Parsley	Tomatoes, asparagus, roses	Beetles
Rosemary	Beans, cabbage, carrots	Bean beetles, cabbage moths, carrot fly
Sage	Brassicas, carrots, strawberries	Cabbage moths, carrot fly, slugs
Thyme	Brassicas, strawberries	Cabbage worms, slugs
Borage	Tomatoes, squash, strawberries	Hornworms, worms

Flowers as Companion Plants

Marigolds: The Ultimate Companion

French marigolds are powerhouse companion plants for vegetables

Varieties and Effects:

Variety	Best For	Special Properties
French marigold (Tagetes patula)	Nematode control	Roots release thiophenes
African marigold (Tagetes erecta)	Aphid repellent	Strong scent masks crops
Signet marigold (Tagetes tenuifolia)	Edible, beneficial attractant	Lemon-scented, edible flowers

How to Use Marigolds:

• Plant 3-4 per tomato plant for nematode control
• Border entire vegetable garden
• Interplant throughout beds
• Deadhead for continuous bloom

Scientific Note: French marigolds’ root exudates reduce root-knot nematodes by 70-99% when planted as a cover crop the season before.

Nasturtiums: The Trap Crop Champion

Benefits:

• Trap crop for aphids (sacrifice to protect other plants)
• Repel squash bugs and cucumber beetles
• Attract pollinators
• Edible flowers and leaves

Usage:

• Plant 12-18 inches from brassicas for aphid protection
• Plant at ends of cucumber rows
• Allow to sprawl as ground cover

Calendula (Pot Marigold)

Benefits:

• Attracts beneficial insects (hoverflies, lacewings)
• Trap crop for aphids
• Edible petals
• Long blooming period

Borage

Benefits:

• Attracts pollinators and beneficial wasps
• Repels tomato hornworms
• Adds trace minerals to soil
• Edible flowers taste like cucumber

Alyssum

Benefits:

• Attracts hoverflies (aphid predators)
• Living mulch
• Long blooming season
• Sweet fragrance

Sunflowers

Benefits:

• Support for climbing beans
• Shade for heat-sensitive crops
• Attract pollinators
• Bird food (protect heads with bags)

Caution: Sunflowers are allelopathic to beans—plant beans on north side only, after sunflowers are established.

The Science of What NOT to Plant Together

Incompatible Combinations

Plant A	Plant B	Reason
Beans	Onions/Garlic	Onions inhibit bean growth
Beans	Sunflowers	Allelopathic inhibition
Tomatoes	Potatoes	Shared diseases (blight)
Tomatoes	Fennel	Fennel inhibits tomato growth
Tomatoes	Corn	Shared pest (tomato fruit worm/corn earworm)
Brassicas	Strawberries	Compete for nutrients
Carrots	Dill	Mature dill stunts carrots
Cucumbers	Potatoes	Compete for nutrients
Peppers	Beans	Excess nitrogen from beans
Fennel	Most vegetables	Allelopathic to many plants
Walnuts	Most vegetables	Juglone toxicity

Companion Planting Layout Strategies

Strategy 1: The Guild Approach

Create plant “guilds” where multiple companions support a central crop:

Tomato Guild Example: “` [Marigold] [Chive] [Chive] [Basil] [Tomato] [Basil] [Parsley] [Parsley] [Carrot] “`Apple Tree Guild Example (for orchards):

• Central: Dwarf apple tree
• Understory: Comfrey (dynamic accumulator), dill, fennel (beneficial insect attractors)
• Ground cover: Clover (nitrogen fixer), nasturtiums (pest trap)
• Bulbs: Daffodils (repel deer, gophers)

Strategy 2: Row Interplanting

Alternate rows of companions:

“` Row 1: Carrots + Onions Row 2: Lettuce + Radishes Row 3: Carrots + Onions Row 4: Lettuce + Radishes “`

Benefits:

• Easy to implement
• Efficient use of space
• Clear organization
• Simple crop rotation

Strategy 3: Border Planting

Use companion plants as protective borders:

“` [Marigold Border] [Chive Border] [Main Vegetable Bed] [Chive Border] [Marigold Border] “`

Strategy 4: Trap Crop Islands

Place sacrificial plants strategically:

“` [Nasturtium cluster] [Nasturtium cluster]

[Cucumber bed]

[Nasturtium cluster] [Nasturtium cluster] “`

Strategy 5: Beneficial Insect Attractor Strips

Plant flower strips to attract predators:

“` [Vegetable bed] [Flower strip: alyssum, calendula, dill] [Vegetable bed] “`

Sample Companion Planting Garden Layouts

Layout 1: The Classic Tomato Bed (4×8 feet)

“` [N][Marigold][Marigold][Marigold][Marigold][Marigold][N]

[Chive] [Basil] [Tomato] [Tomato] [Basil] [Chive]

[Onion] [Parsley] [Tomato] [Tomato] [Parsley] [Onion]

[Chive] [Basil] [Tomato] [Tomato] [Basil] [Chive]

[Carrot][Carrot][Carrot][Carrot][Carrot][Carrot]

[S][Marigold][Borage][Nasturtium][Borage][Marigold][S] “`

N = North side, S = South side

Layout 2: The Brassica Defense Grid (4×8 feet)

“` [N][Sage][Thyme][Rosemary][Thyme][Sage][N]

[Garlic][Broccoli][Onion][Kale][Onion][Broccoli][Garlic]

[Nasturtium] [Nasturtium]

[Onion][Cabbage][Garlic][Cauliflower][Garlic][Cabbage][Onion]

[Nasturtium] [Nasturtium]

[S][Chamomile][Dill][Chamomile][Dill][Chamomile][S] “`

Layout 3: The Three Sisters Classic (8×8 feet)

“` [Squash hill]

[Mound 1] [Mound 2] [Mound 3] Corn/Beans Corn/Beans Corn/Beans

[Squash hill] [Squash hill]

[Mound 4] [Mound 5] [Mound 6] Corn/Beans Corn/Beans Corn/Beans

[Squash hill] “`

Each mound: 4-foot diameter, 6 corn plants in center, 4 bean plants per corn, squash between mounds.

Layout 4: The Market Garden Mix (10×20 feet)

Block 1 (4×4): Tomato guild Block 2 (4×4): Pepper guild Block 3 (4×4): Cucumber guild Block 4 (4×4): Brassica guild Block 5 (4×4): Root vegetable guild Border: Marigolds, nasturtiums, alyssum

Companion Planting for Pest Management

Common Pest Solutions

Pest	Companion Solution	How It Works
Aphids	Nasturtiums, calendula	Trap crop, attract predators
Cabbage worms	Dill, thyme, rosemary	Attract parasitic wasps, repel moths
Tomato hornworms	Borage, basil	Attract predators, repel moths
Carrot rust fly	Onions, chives, rosemary	Mask carrot scent
Cucumber beetles	Nasturtiums, radishes	Repel or trap
Bean beetles	Rosemary, nasturtiums	Repel beetles
Slugs	Sage, rosemary, thyme	Aromatic deterrent
Nematodes	French marigolds	Root exudates toxic to nematodes
Whiteflies	Marigolds, nasturtiums	Repel with scent
Squash bugs	Nasturtiums, oregano	Repel or trap

Attracting Beneficial Insects

Predatory Wasps (control caterpillars, aphids):

• Dill
• Fennel
• Cosmos
• Yarrow
• Queen Anne’s lace

Hoverflies (aphid predators):

• Alyssum
• Calendula
• Buckwheat
• Sweet alyssum
• Coriander

Lacewings (general pest predators):

• Dill
• Angelica
• Cosmos
• Sunflowers
• Dandelions (allow some!)

Ladybugs (aphid control):

• Dill
• Fennel
• Yarrow
• Feverfew
• Butterfly weed

Parasitic Wasps (caterpillar control):

• Dill
• Parsley
• Fennel
• Lemon balm
• Thyme

Seasonal Companion Planting

Spring Companions

Early Planting (cool season):

• Peas with carrots and radishes
• Spinach with strawberries
• Lettuce with onions and carrots
• Broccoli with dill and onions

Spring Flowers to Add:

• Calendula
• Sweet alyssum
• Borage

Summer Companions

Warm Season:

• Tomatoes with basil and marigolds
• Peppers with basil and onions
• Cucumbers with beans and nasturtiums
• Corn with beans and squash (Three Sisters)

Summer Flowers to Add:

• Marigolds
• Zinnias (attract pollinators)
• Sunflowers

Fall Companions

Cool Season Return:

• Brussels sprouts with sage and thyme
• Carrots with onions and rosemary
• Kale with garlic and nasturtiums
• Lettuce with radishes and chives

Fall Flowers to Add:

• Chrysanthemums (repel insects)
• Calendula (continue blooming)
• Alyssum

Troubleshooting Companion Planting

Problem: Companions Are Crowding Each Other

Solution:

• Follow spacing guidelines strictly
• Use vertical space for vining companions
• Harvest quick-maturing companions early
• Thin plants appropriately

Problem: One Companion Is Overwhelming the Other

Solution:

• Avoid aggressive spreaders (mint, oregano) near slow growers
• Plant aggressive herbs in containers
• Prune or harvest dominant plants
• Choose compatible growth rates

Problem: Pest Control Isn’t Working

Possible Causes:

• Not enough companion plants (need critical mass)
• Planted too far apart
• Wrong variety (use French marigolds, not African)
• Timing issue (companions not established when pests arrive)

Solutions:

• Increase density of companion plants
• Plant companions 2-3 weeks before main crop
• Use multiple companion strategies
• Combine with other organic methods

Problem: Companions Competing for Resources

Signs: Stunted growth, yellowing, poor productionSolutions:

• Ensure adequate spacing
• Provide supplemental water and fertility
• Use plants with different root depths
• Harvest or thin aggressive plants

Advanced Companion Planting Techniques

Succession Companion Planting

Plan companions for continuous coverage:

Example Sequence: 1. Early Spring: Peas with radishes and spinach 2. Late Spring: Replace peas with cucumbers, keep radishes 3. Summer: Cucumbers with beans and nasturtiums 4. Fall: Replace cucumbers with brassicas, keep nasturtiums

Vertical Companion Planting

Use vertical space for companion benefits:

Three-Dimensional Guild:

• Tall: Sunflowers or corn
• Middle: Pole beans (fix nitrogen)
• Low: Nasturtiums (ground cover, pest trap)

Container Companion Planting

Best container combinations:

Container Size	Combination	Notes
5-gallon	Tomato + basil + marigold	Classic trio
3-gallon	Pepper + basil + parsley	Herb enhanced
18-inch	Cucumber + nasturtium + oregano	Pest protected
Window box	Lettuce + radish + chive	Quick harvest
Hanging basket	Cherry tomato + basil	Trailing varieties

The Don’t-Overthink-It Rule

While companion planting offers many benefits, remember:

1. Healthy soil matters most: Companions help, but can’t compensate for poor soil 2. Proper spacing is critical: Overcrowding causes more problems than wrong companions 3. Plants want to grow: Most combinations work fine even if not “perfect” 4. Observe and adapt: Your specific conditions determine what works best 5. Have fun experimenting: Try different combinations and note results

Conclusion: Planting in Partnership

Companion planting transforms your garden from a collection of individual plants into an interconnected ecosystem. By understanding these plant partnerships, you create gardens that are more productive, more resilient, and more beautiful.

Start with a few proven combinations—tomatoes with basil, carrots with onions, brassicas with aromatic herbs—and expand your companion planting repertoire as you gain confidence. Keep notes on what works in your garden, and don’t be afraid to experiment.

Remember these companion planting fundamentals:

• Diversity is protection: Mixed plantings confuse pests
• Flowers are essential: They attract the good bugs
• Aromatics are armor: Scented herbs repel many pests
• Some plants need space: Respect incompatible combinations
• Observe and adapt: Every garden is unique

Happy companion planting!

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