Companion planting for tomatoes: best & worst plant garden pairings

If you want a thriving vegetable garden with healthier plants and bigger harvests, companion planting is a simple, natural way to improve growth and deter pests. Tomatoes, a staple in many Australian gardens, benefit significantly from the right plant companions. In this guide, we’ll cover the best plants to grow alongside your tomatoes, the ones to avoid, and how to make the most of companion planting for a bumper crop in your vegetable garden. 

 

Why companion planting works 

Companion planting involves strategically placing certain plants together to create a more balanced ecosystem, benefiting overall plant health and improving garden resilience. The right combinations can: 

  • Enhance soil fertility by adding or preserving nutrients 

  • Improve pollination by attracting beneficial insects 

  • Maximise space in your veggie garden 

  • Enhance flavour in fruits and vegetables 

For tomatoes, companion planting can help reduce common problems like aphids, whiteflies, and fungal diseases, while also supporting strong, productive plants – music to a gardener's ears.

 

Best companion plants for tomatoes 

Here are some of the top herbs, flowers and vegetables to grow alongside your tomatoes: 

1. Basil 

The classic companion for tomatoes, basil is not only great to eat with tomatoes but, also repels pests like aphids, whiteflies, and mosquitoes. Plus, they thrive under similar growing conditions (and you can never have enough basil!). 

A simple basil and tomato salad with a good amount of olive oil, salt and pepper must be one of our favourite summer foods. Anyone else?

2. Marigolds 

These vibrant, joyful and easy-care flowers are excellent for deterring nematodes and repelling aphids, whiteflies, and other common garden pests. Marigolds also attract pollinators, boosting fruit production (the flower petals are awesome for taking salads to the next level too). 

3. Garlic & Chives 

Both garlic and chives help repel aphids, spider mites, and fungal diseases. Their strong scent can also deter larger pests like rabbits and possums. Also, another plant that goes well with tomatoes in a culinary sense! Talk about companion plants.

4. Carrots 

Carrots grow well under tomato plants, making use of space efficiently. Their presence can also help aerate the soil, which benefits tomato root growth, just don’t grow carrots too close to the roots of tomatoes. 

5. Lettuce & Spinach 

These leafy greens enjoy the shade provided by tomato plants and help suppress weeds while retaining soil moisture. Lettuces are definitely a staple in our garden (and kitchen) year after year.

6. Nasturtiums 

A natural trap crop, nasturtiums attract aphids away from tomatoes while also luring pollinators into your garden. Also, beautiful in salads! 

7. Borage 

Borage attracts bees, beneficial insects, and other pollinators, while also deterring tomato hornworms. Plus, it adds nutrients back into the soil, and it's a beautiful addition to any garden. I use these flowers in salads, on top of desserts, and in summer drinks with lemon. 

 

Plants to avoid near tomatoes 

Just as some plants enhance tomato growth, others can hinder it. Here are a few plants to keep away from your tomato patch: 

1. Potatoes 

Both potatoes and tomatoes belong to the nightshade family (solanum) and are susceptible to the same diseases, like blight, which can spread between them. Other solanums to avoid co-planting are eggplant, capsicums, tomatillos and chilies. Hot tip: look at the seeds of these plants, they all look almost exactly the same! 

2. Corn 

Corn attracts pests such as the tomato fruit worm, which can quickly damage your tomato plants. 

3. Fennel 

Fennel secretes chemicals that inhibit the growth of nearby plants, including tomatoes. 

4. Cabbage & Brassicas (broccoli, cauliflower, kale) 

These plants are big nutrient feeders and compete strongly for nutrients with tomatoes, which can lead to stunted growth. 

5. Dill 

While young dill can benefit tomatoes, mature dill can inhibit their growth, so it’s best kept in a separate part of the garden. 

 

Check out this companion planting chart

Our friends at Sustainable Gardening Australia have a great companion planting chart that we recommend you refer to. Find it here.

 

Tips for successful companion planting with tomatoes 

  • Rotate crops: Avoid planting tomatoes (and other solanums) in the same spot each year to prevent soil depletion and disease build-up. 

  • Use mulch: A layer of mulch helps retain soil moisture and prevent disease spread. 

  • Plant in clusters: Grouping companion plants together enhances their benefits, such as pest control and pollination support. 

  • Encourage pollinators: Adding flowering plants like marigolds and nasturtiums will attract beneficial insects, improving tomato yields and other vegetables. 

  • Provide support: Use stakes or cages to keep tomato plants off the ground, reducing disease risk and improving airflow. These are great for garden beds.

  • Keep watering low to the ground to lessen the potential of fungal disease with drip irrigation or slow-release water systems like ‘ollas’. These are some of our favourites.

Remember, if your garden is thriving and you have a mini ecosystem going on with an understory and ‘canopy’ it will be absorbing more water than just a monoculture of staked tomatoes but well worth it! 

 

Final thoughts 

Companion planting is an easy and natural way to improve your tomato harvest (and overall gardener journey) while reducing pests and promoting biodiversity in your garden. If you consider planting companion plants and avoiding the ones that hinder growth, you’ll set your tomatoes up for success whilst increasing your bounty of garden beauty and culinary delights 😊 .

Our favourite part about companion planting is that at the end of the day, your garden beds are going to be blooming with a varied assortment of plants that, combined, create a tiny ecosystem right at home, attracting pollinators and other beneficial insects into your garden bed.

Looking for more natural gardening tips or need some help getting your gardening journey started? We've got plenty of resources. We highly recommend you check out our recent compost guide to start your own home composting with confidence, or read through our tips to help your new seedlings adapt to their new garden bed.

Happy gardening!