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Interplanting isn’t just about maximizing space—it can be a powerful tool for biocontrol, helping reduce pest damage naturally. By strategically placing certain plants next to your vegetables, you can deter harmful insects, attract predators, or confuse pests, minimizing the need for chemical interventions.

How Interplanting Controls Pests

1. Repellent Plants: Some herbs and flowers release scents that deter pests.
   • Examples: Marigolds (nematodes, aphids), basil (whiteflies), garlic/onions (various insects).
   • Use: Plant alongside tomatoes, peppers, or brassicas.
2. Trap Crops: These attract pests away from main crops.
   • Examples: Nasturtiums lure aphids away from cabbage or cucumbers.
   • Use: Plant at field edges or near vulnerable crops.
3. Attracting Beneficial Insects: Certain plants provide nectar, pollen, or shelter for predators and parasitoids.
   • Examples: Dill, fennel, coriander, alyssum attract ladybugs, lacewings, parasitic wasps.
   • Use: Interplant near crops prone to aphids, caterpillars, or whiteflies.
4. Confusion or Masking: Some companion plants mask the scent of main crops, making it harder for pests to find them.
   • Examples: Strongly aromatic herbs like rosemary, sage, or thyme.
   • Use: Plant around susceptible crops like brassicas or tomatoes.

Timing and Placement

• Plant repellent or beneficial flowers/herbs at the same time as your main crop or slightly earlier to establish them.
• Trap crops should be planted early enough to attract pests before the main crop is vulnerable.
• Mix different strategies in one bed: repellent plants at the edges, beneficial flowers scattered among vegetables, trap crops nearby.

Key Benefits

• Reduced pest populations without chemicals
• Increased presence of natural predators
• Improved crop health and yield
• Supports biodiversity in your garden

By using strategic interplanting, you create a balanced ecosystem where pests are controlled naturally and your vegetables thrive. Over time, this approach can reduce chemical use and improve soil and plant health.

Vegetable Garden Biocontrol Companion Chart

Vegetable	Companion Plants	Pest Targeted / Biocontrol Effect	Timing / Notes
Tomatoes	Basil	Repels whiteflies, aphids, tomato hornworms	Plant at transplant or around bed edges
	Marigolds	Repel nematodes, aphids	Plant same day or slightly earlier
	Nasturtiums	Trap aphids	Plant nearby; harvest aphids by hand
	Dill	Attracts ladybugs and parasitic wasps	Sow at same time as transplants
Peppers	Basil	Repels aphids, whiteflies	Plant at transplant
	Marigolds	Repel nematodes	Plant at bed edges
	Alyssum	Attracts hoverflies (aphid predators)	Plant between rows
Cucumbers	Nasturtiums	Trap aphids	Sow at same time; edges of beds
	Dill	Attracts parasitic wasps	Interplant early
	Radishes	Confuses cucumber beetles	Plant with main crop
Squash / Pumpkins	Nasturtiums	Trap aphids and beetles	Plant edges or within patch
	Marigolds	Deters nematodes	Plant at same time
	Corn	Provides structure for beneficial insects	Plant together in Three Sisters method
Cabbage / Brassicas	Dill, Fennel, Cilantro	Attracts parasitic wasps (cabbage worms, loopers)	Sow at transplant or slightly earlier
	Nasturtiums	Trap aphids	Plant nearby
	Marigolds	Repel nematodes	Plant around bed edges
	Onions, Garlic	Repel aphids, cabbage moths	Plant at same time
Carrots	Onions, Leeks	Repel carrot flies	Plant same time
	Radishes	Trap pests, break soil surface	Sow with carrots
	Dill, Fennel	Attract parasitic wasps	Plant early
Beets	Onions	Repel aphids	Plant same day
	Marigolds	Deter nematodes	Plant around bed edges
	Bush beans	Attract beneficial predators	Interplant early
Lettuce / Greens	Garlic, Chives	Repel aphids, leaf miners	Plant nearby or between rows
	Marigolds	Repel nematodes	Plant edges
	Nasturtiums	Trap aphids	Plant near greens
Corn	Beans	Fix nitrogen; attract beneficial insects	Plant when corn 6–12” tall
	Sunflowers	Provide structure for parasitic wasps	Plant same day
	Nasturtiums	Trap aphids	Interplant along edges
Onions / Garlic	Carrots	Deter carrot flies	Plant same time
	Lettuce	Reduce aphids	Plant in gaps
	Brassicas	Repel cabbage worms	Plant nearby
Herbs / Flowers for Biocontrol	Alyssum	Attract hoverflies (aphid predators)	Plant near tomatoes, peppers
	Marigolds	Repel nematodes	Plant near most vegetables
	Dill, Fennel, Cilantro	Attract parasitic wasps	Plant near brassicas
	Nasturtiums	Trap pests	Plant with cucumbers, squash, tomatoes
	Basil	Repels whiteflies, aphids	Plant near tomatoes and peppers

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Tips for Using the Chart

1. Repellents go along bed edges or near vulnerable crops.
2. Trap crops go on bed edges or as dedicated small patches.
3. Beneficial-attracting plants should be scattered throughout beds or along pathways.
4. Timing: plant companion herbs and flowers slightly before or at the same time as main crops for maximum effect.
5. Rotation: Change companion placements each season to avoid pest buildup in one area.