In this article I will cover the following topics:
- What is Companion Planting?
- Benefits of Companion Planting to Tomatoes
- Companion Plants to Attract Pollinators and other Beneficial Insects
- Companion Plants to Repel Pests
- Companion Plants to Reduce Disease spread
- Tomato’s Best Companions
- Plants to Avoid Near Tomatoes
- Final Tips for Success
What is Companion Planting?
The Science of Companion Planting: Best Partners for Thriving Tomatoes
When it comes to growing tomatoes, gardeners often focus on sunlight, water, and soil. But there’s another powerful, often overlooked tool in the organic gardener’s toolkit: companion planting. This time-tested method involves growing certain plants together to naturally enhance growth, improve flavor, and deter pests. In the case of tomatoes, choosing the right companions can mean the difference between a struggling crop and a thriving harvest.
Benefits of Companion Planting to Tomatoes
Why Companion Planting Works
Companion planting isn’t just folklore—it has a solid foundation in plant science. Many plants interact through allelopathy (chemical signaling), root structure synergy, and pest behavior modification. Generally there are a few studied categories botanists focus on. Some plants can:
- Attract beneficial predators and pollinators.
- Repel or confuse harmful insects.
- Improve soil nutrient availability.
- Provide natural trellises or ground cover to reduce disease spread
Companion Plants to Attract Pollinators and other Beneficial Insects
Companion planting with flowers and herbs that attract pollinators and beneficial insects is a natural and effective way to enhance garden health and productivity. Plants such as lavender, borage, yarrow, and calendula draw bees, butterflies, and hoverflies, which help increase pollination rates for fruits and vegetables. Additionally, herbs like dill, fennel, and cilantro attract predatory insects like ladybugs and parasitic wasps that help control pests such as aphids and caterpillars. By interplanting these companions throughout the garden, gardeners create a balanced ecosystem that reduces the need for chemical pesticides and supports a thriving, biodiverse environment.
Increase pollination
- Sunflowers
- Rudbeckia
- Calendula
- Coneflowers
- Peas and other hooded flowers
- Yarrow
- Hollyhocks
- Lavender
- Borage
Increase beneficial insects
Beneficial insects are attracted to the nectar in the bloom. Therefore, for these herbs to do their job, you need to let them go to flower.
- Oregano
- Cilantro
- Dill
- Fennel
- Sweet alyssum
Companion Plants to Repel Pests
Companion planting can also be used strategically to repel or confuse harmful pests, protecting crops and reducing damage to crops without relying on synthetic pesticides. Certain plants emit strong scents or chemicals that deter pests or mask the scent of nearby crops. For example, marigolds are well known release compounds that repel nematodes and aphids, while basil can help keep mosquitoes, thrips, and tomato hornworms at bay when planted near tomatoes. Similarly, aromatic herbs like rosemary, sage, and thyme can mask the scent of nearby vegetables, making it harder for pests to locate their preferred hosts.
By mixing these pest-repelling plants among vulnerable crops, gardeners can disrupt pest life cycles and reduce infestations without relying on synthetic pesticides, promoting a healthier and more resilient garden.
- Basil
- Marigolds
- Rosemary
- Sage
- Thyme
- Radish
Companion Plants to Reduce Disease Spread
Generally when botanists talk about reducing disease, they are referring to reducing spread. Companion planting can play a key role in reducing the spread of plant diseases by improving air circulation, creating physical barriers, and disrupting the transmission pathways of pathogens. By diversifying plant species in a garden, rather than growing a single crop in dense clusters, the chances of disease spreading from plant to plant are significantly reduced.
For example, planting garlic or chives near susceptible vegetables can help deter fungal diseases due to their natural antifungal properties. Additionally, alternating rows of different plants can limit the movement of soil-borne diseases and insect vectors that carry viruses. This strategic spacing and diversity make it harder for infections to take hold and spread, leading to healthier, more resilient plants.
The way diseases are often spread is from the soil up. This could be from splashing or even systemic spread. So some of the best tomato disease fighters are plants that will shield splashes from the soil in rainy weather or from hand-watering, such as bean plants, which are less susceptible to the diseases which live in the soil.
Tomato’s Best Companions
Here are some of the most scientifically backed companion plants for tomatoes:
1. Basil (Ocimum basilicum)
- Benefits: Repels aphids, whiteflies, and hornworms. Some studies suggest basil may improve tomato flavor.
- Science: Basil releases volatile oils like eugenol and linalool that act as natural insect repellents.
2. Marigolds (Tagetes spp.)
- Benefits: Known to suppress root-knot nematodes and repel aphids and whiteflies.
- Science: Compounds like thiophenes produced by marigold roots have pesticidal properties.
3. Chives and Onions (Allium spp.)
- Benefits: Help deter red spider mites and aphids.
- Science: Their strong sulfuric compounds act as insect deterrents and mild antifungals.
4. Carrots (Daucus carota)
- Benefits: Can aerate the soil around tomato roots.
- Note: May slightly stunt each other’s growth, but can be timed so carrots are harvested early.
5. Lettuce and Spinach
- Benefits: Low-growing greens provide living mulch, reduce weed growth, and keep soil moist.
6. Borage (Borago officinalis)
- Benefits: Attracts pollinators and predatory insects like lacewings. It’s also believed to deter tomato hornworms.
- Science: Its high nectar output attracts beneficial insects that help balance pest populations.
Plants to Avoid Near Tomatoes
Some plants compete with tomatoes or attract pests:
- Brassicas (like cabbage, broccoli): Compete for nutrients and may attract similar pests.
- Corn: Can attract tomato fruitworm (also known as corn earworm).
- Fennel: Known to inhibit growth of nearby plants via allelopathic chemicals.
- Potatoes: Share susceptibility to blight; planting together increases disease risk.
Final Tips for Success
- Rotate your crops yearly to avoid soil-borne diseases.
- Use companion plants as part of a holistic pest management strategy, not the only method.
- Observe your garden: companion planting is as much about experimentation as it is science.
In Summary: Companion planting with tomatoes is both practical and ecological. By pairing your tomatoes with allies like basil, marigolds, and borage, you’re not just planting a garden—you’re creating a community where plants work together to thrive
