There is so much possibility when you grow tomatoes in your vegetable garden, especially when using herbs as tomato companion plants. From eating raw slices on a sandwich, to processing and canning them into paste or salsa, the options are never ending. Did you know that you can improve your tomato yields by strategically growing beneficial tomato companion plants near them? Basil and tomatoes, marigolds and tomatoes . . . the list is endless.
In this post we are going to chat about the best and worst tomato companion plants so that you can grow your most productive tomato crop yet! We’ll even talk about a few others, like basil companion plants (since we’ll already be talking about basil!)
What is Companion Planting?
Before we jump in, let’s talk a little about what companion planting is and what you should think about before planning your companion plants.
Companion planting is a gardening method in which mutually beneficial plants are grown next to each other. This can help to improve the flavor, growth, and productivity of fruits, vegetables, and herbs.
What to Consider Before Companion Planting
Before you plan your garden, and especially before putting your plants in the ground, there are several factors you should consider.
Soil nutrients: consider the nutrients—like nitrogen, potassium, and phosphorus—that each plant needs.
Light requirements: a plant that needs a large amount of full sun will not need to grow beside a tall plant that creates shade.
Water Requirements: a plant that needs lots of water shouldn’t grow with plants that get overwatered easily.
Disease susceptibility: don’t grow plants together if they are both susceptible to the same diseases and pests.
Root size: consider the root size of the full grown plant to be sure you don’t grow companion plants too close together.
Attracted bugs: different plants attract different insects. Try not to grow plants together if one plant is destroyed by the insect that the other attracts. The exception for this would be a trap crop, like parsley.
Negative impact on neighboring plants: some plants, like fennel and dill, release chemicals that can stunt the growth of surrounding plants. These plants should either be harvested and removed before they reach maturity, or they should be planted by themselves.
What are the Benefits of Companion Planting with Tomatoes
Companion planting has many benefits including:
- Pest Control
- Beneficial Insect/Pollinator Attraction
- Weed Control
- Disease Suppression
- Soil Fertility
- Flavor Enhancement
- Increased Yields
The Best Herbs as Tomato Companion Plants
It is a great idea to companion pant with herbs because, typically, herbs are easy to grow and they can be cooked with the veggies in your garden, or preserved to use in dishes later in the year. Let’s discuss the most common herbs to grow with tomatoes.
Basil is easily the most common tomato companion plant. It has been shown to repel aphids, white flies, spider mites, and hornworms which are all detrimental to tomato plants.
Basil also attracts beneficial pollinators after it goes to seed, and it can enhance the flavor of your tomatoes.
Other great basil companion plants include: cabbage, bell peppers, potatoes, beets, beans, eggplant, and asparagus
Basil is also a fabulous medicinal herb and can be used for respiratory ailments, inflammation, and upset stomach.
Thyme deters the tomato hornworm and it works great as a ground cover to help control weeds.
Thyme is also an incredible medicinal herb, and is most often used in cough syrups to ease coughing. It also has antimicrobial properties.
Chives repel aphids from the garden. They also help to improve the flavor of tomatoes.
Sage planted near tomatoes can repel flea beetles that are known to eat the leaves of tomato plants. Sage also attracts beneficial insects to the garden.
Sage is also a fantastic herb for respiratory ailments and the lungs. It also helps increase memory function and aides in indigestion. It’s a fabulous herb for any mouth ailments, including sore throat.
Mint is used to deter spider mites and aphids from tomato plants. This herb also works to improve the flavor of tomatoes. It is recommended to plant mint in its own container near the tomatoes because it can become invasive to your garden.
Mint is a natural anti inflammatory, headache and fever reducer, and helps aid in digestion.
Parsley that has gone to flower will attract hoverflies which are beneficial insects that kill aphids. Parsley can be used as a trap crop as well. Plant sacrificial parsley near tomatoes to lure aphids away from your tomato plants.
7. Sweet alyssum
Sweet Alyssum is wonderful to plant at the base of tomato plants. This herb works well as a ground cover to control weeds, and it attracts pollinators to the garden.
Borage is known to deter tomato hornworms. It attracts pollinators, and it improves the growth and flavor of the tomatoes. Borage is also great to throw into the compost bin when it has reached the end of its life.
Borage also has some medicinal benefits, but should be used with care. It is known to help with respiratory ailments, dermatitis, and even arthritis.
The ideal tomato companion plant combination (second to basil & tomatoes) is marigolds and tomatoes.
Marigolds are a triple threat in the vegetable garden:
- They repel harmful hornworms, slugs, and nematodes.
- They attract pollinators & parasitic wasps.
- They are edible & medicinal.
Plant marigolds along the edges of your garden or between tomatoes to reap these benefits. If you are starting from seed, be sure to plant the marigolds about six weeks before planting tomatoes in order to reduce the nematode population.
Marigolds and tomatoes aren’t just the perfect pair because of growing efficacy. They are also great companions because both are edible in salads and other treats. Calendula (or pot marigold) is the best tasting marigold, and also has great medicinal healing properties when it comes to treating the skin of bruises, cuts, and more.
Other Common Tomato Companion Plants
The smell of garlic is known to deter aphids and spider mites away from tomato plants. Garlic also attracts beneficial ladybugs and parasitic wasps which kill tomato hornworms.
Onions release a pungent chemical that repels aphids.
Carrots can be planted near the base of tomato plants to help aerate the soil.
Asparagus repel nematodes that are harmful to tomato plants.
What Should You NOT Plant with Tomatoes?
While dill does attract predators of the tomato hornworm, it must be removed before it matures or it will release a chemical that can stunt the growth of the tomato plants.
Fennel attracts several beneficial insects, but it has been found to inhibit the growth of many vegetables. It is best not to plant fennel near any vegetables, especially tomatoes.
Plants in the brassica family tend to inhibit the growth of tomato plants. These plants also prefer a more neutral soil than tomatoes. This includes broccoli, cabbage, kale, kohlrabi, collards, brussels sprouts, cauliflower, turnips, and rutabagas.
Corn is an attractant for the tomato fruit worm which can be detrimental to a tomato plant.
Eggplant is in the nightshade family with tomatoes. It is susceptible to the same diseases (like blight) and insects (like hornworms).
Walnuts produce a substance called Jugalone that will stunt the growth of tomatoes. Walnut trees produce this substance to kill off plants that are competing for nutrients. It not only stunts the growth, but can also cause Walnut Wilt.
Potatoes are in the nightshade family with tomatoes. They are susceptible to the same diseases (like blight) and insects (like hornworms).
Just like eggplant and potatoes, peppers are found in the nightshade family with tomatoes. Peppers are susceptible to the same diseases (like blight) and insects (like hornworms), so they shouldn’t be planted with tomatoes.
Ultimately, whether you choose to plan out your garden with companion plants, or just throw it all in there and see what happens, it’s good to know that all plants have a purpose, and a reaction. Take for example, marigolds and tomatoes being some of the best companions yet, and both having separate purposes for the homesteader. Marigolds and tomatoes truly are a staple companion in the garden.
Or take basil companion plants. Did you see how many companions basil has that could also benefit tomatoes? Likewise, there are some plants to stay away from. Each companion plant having its own harmonious (or not so harmonious) relations with the other plants in the garden.
Enjoy this garden season, and I hope you learned something fun!