Guide to Tomato Companion Plants

Are you looking to boost the health and growth of your tomato plants? Companion plants can be an excellent way to accomplish your gardening goals! If you’re hoping to benefit from this gardening strategy, chances are, you’ll also benefit from this guide to tomato companion plants!

Tomato plants flourish in conditions of full sunlight, drained soil mixtures with 6.2 to 6.8 levels of pH, and warm temperatures. These conditions make plants like lettuce, borage, and basil beneficial companions to the tomato plant. This is especially true because such companions can warn away pests like tomato hornworms and aphids and enrich the soil.

Updated: June 8, 2024.

In the following guide, we’ll go over everything that a tomato plant needs in order to grow healthily, then provide a list of companion plants that help fulfill those needs, as well as answer some frequently asked questions on the subject!

What Are the Proper Growing Conditions For Tomato Plants?

If we’re going to understand the best ways to help our tomato plants through companion plants, the first step is understanding which conditions tomatoes grow best in! Let’s check out the conditions and requirements below.

• Soil – The soil of a tomato plant should be fertilized at least 2 weeks before the tomato is actually planted. Even then, the area should be drained, not overly moist, and in a bright area. This soil should be low in nitrogen but high in acidity, as discussed below!
• pH Levels – Some plants need more acidity or alkalinity in their soil to thrive. pH levels are how we refer to these components. A tomato plant needs more acidic soil: you should have pH levels that are around 6.2 at the least to 6.8 at most. This will give you the best fruit!
• Sunlight – The tomato plant is happiest when it is in full and complete sunshine. It can handle the brightness of the ultraviolet rays for the entire day and thrive on it. In fact, a tomato plant is recommended to be given at least eight hours of full sunshine each day for the healthiest results.
• Nutrients – The three main nutrients that a tomato plant needs to thrive can be found in the pH levels of the soil and the fertilizer: phosphorus, potassium, and nitrogen. The quickest way to give your tomato plants what they need in terms of nutrients is to find a fertilizer that combines all three!
• Temperature – The temperature that a plant is exposed to determines how well the plant produces color, both in the stems and foliage and the actual trademark color of the fruit itself. Temperature needs may vary depending on the type of tomato plant you are growing, but generally, tomatoes are grown between 55 degrees and 85 degrees.
• Water – Your crop of tomatoes likely requires around 1 to 2 inches of H2o every week unless the tomato plant is grown in a type of container, which causes the water to evaporate more easily. If this is the case, add a little more water to your routine care of your tomato plant.

If your tomato plant is cared for under these conditions, there should be no reason why it does not thrive! When defending your tomato plant against disease or pests, a companion plant, like those discussed below, can be just what your garden or farm needs.

Best Companion Plants For Tomato Plants

With the proper growing conditions for tomato plants firmly established, we can move on to seeing which plants make great companions for our tomatoes!

• Carrots
• Basil
• Borage
• Lettuce
• Marigolds

Let’s look a little more closely at each of these plants to see how their attributes can benefit the growth of our tomato plants.

Carrots

Carrots are not only tasty when combined with tomato fruits, but their plants grow in some of the same conditions!

A carrot plant needs some shade, which can be provided by the taller tomato plant, but otherwise does fine in the sunny location that tomato plants need to thrive. They also only need around an inch of water, similar to the tomato plant.

The main benefit derived from carrots near a tomato plant is that they can loosen up the soil surrounding a tomato plant. As previously stated, tomato plants have the most to gain from soil that is aerated or receives enough oxygen flow to prevent root rot.

Therefore, a carrot plant’s ability to separate soil clumps is very helpful to the growth of tomatoes!

Basil

Who doesn’t love tasty basil leaves paired with tomatoes on pasta, margarita pizza, or even in salads? The savory basil leaves aren’t just great for eating with tomatoes; they also provide unique benefits to the plant itself during the growing process.

A basil plant can endure warm temperatures and the sunlight that tomato plants love, but it really requires at least a little shade to prevent it from drying out or burning. Luckily, nearby tomato plants as companions can provide this light shade.

In the meantime, the basil plant exudes a particular scent while it grows. You and I may find that smell delicious enough to make us hungry, but guess who hates the smell of basil?

Tomato hornworms, one of the most detrimental and tricky pests to plague tomato gardeners, can’t stand the smell basil plants emit!

Flies and hornworms alike will avoid your tomato plant as long as there is some basil planted nearby!

Borage

Borage is not only a medicinal and yummy herb, but it produces characteristic blue flowers. These blue flowers look pretty in a garden, but did you know that they also attract pollinating insects like bees?

This is wonderful for your tomato plant, but far more beneficial are the ladybugs that love to come around borage and eat the aphids that might harm your crop.

Hornworms also hate the borage plant and, like basil, will avoid your tomatoes if they catch a whiff of this companion.

Finally, borage is also beneficial to a tomato plant because, when grown a few inches from the tomato plant, it releases nutrients into the soil that enhance the flavor and production of tomatoes! Win-win!

Lettuce

Not only are lettuce and tomatoes a match made in heaven in terms of salads, but they can be super helpful to one another as companions in the garden.

Tomato plants tend to absorb the same full sunlight that lettuce needs while offering enough coolness and moisture to the soil below them for lettuce planted nearby to thrive.

Lettuce is not only in an easy-to-reach location for the gardener who decides to grow these two plants together, but it benefits from the same range of pH levels and nutrients, as well as water needs, that tomato plants have. A whole field of these two plants can be grown together very nicely.

Marigolds

Marigolds are wonderful companions for more than one type of vegetable. This is not just because they are beautiful but because they serve as a big red flag for many of the pests that would like to do harm to your tomato plants.

Experts say that marigolds are possibly one of the all-time greatest things you can plant near a tomato plant. Their scent gets rid of hornworms and other pests but attracts friendly, pollinating creatures like butterflies and bees and, of course, our friend, the aphid-eating ladybug!

One of the most harmful critters to a tomato plant is the nematode, which eats plant roots and steals the energy of tomatoes.

Luckily, marigolds secrete a substance in their own roots that works as a poison strong enough to take out whole colonies of nematodes without ever harming your tomato plant! Marigolds are practically a guard dog for tomato plants.

Of course, there are other plants that can be very beneficial when grown near tomatoes, including:

• Garlic - Acts as a natural repellent for spider mites and prevents fungal root diseases,
• Sage - Repels slugs, flea beetles, and spider mites. It also attracts pollinators like butterflies and similar.
• Onions - Repel many insects that harm tomatoes, such as aphids,
• Lavender - Blooming lavender attracts pollinators, increasing the tomato harvest,
• Asparagus - Creates a mutual benefit by deterring some of the tomato pests like nematodes,
• Mint - Deters aphids and ants but should be grown in pots to avoid them taking over the garden,
• Thyme - thyme helps repel ants, grasshoppers, aphids, wireworms, and other tomato pests,
• Cilantro - blooming cilantro attracts beneficial insects like parasitic wasps that prey on hornworms,
• Sunflowers - attract bees and other pollinators, potentially increasing the harvest,
• Oregano - flowering oregano attracts another insect predator - green lacewing, decreasing the number of pest insects on tomatoes,
• Parsley - another plant whose flowers attract beneficial insects - humble ladybugs, which prey on aphids and also consume hornworm eggs,
• Calendula - Attracts beneficial insects such as ladybugs and lacewings, which help control pests.

What not to plant with tomatoes?

There are several plants that should NOT be grown next to tomatoes, including:

• Fennel - Inhibits the growth of tomatoes by secreting substances that are harmful to tomatoes and many other plants,
• Cabbage - Cabbage and its relatives (broccoli, Brussels sprouts, cauliflower, etc.) can inhibit tomato growth due to their extensive nutrient requirements and the potential for root system competition,
• Dill - While young dill plants can be beneficial, mature dill stunts tomato plant growth,
• Peppers - While they don't necessarily harm tomatoes, they are susceptible to the same diseases, and planting them together can spread issues like bacterial spot and blight.
• Eggplants - As members of the same family (nightshade), they are vulnerable to the same pests and diseases, which can proliferate if they are planted together,
• Corn - Both corn and tomatoes are susceptible to the same pest, the corn earworm (which is also known as the tomato fruitworm), leading to shared vulnerabilities,
• Cucumbers - Both cucumbers and tomatoes are susceptible to similar pests and diseases and can compete for nutrients and water,
• Potatoes - Being closely related, they can share diseases, especially blight, which can devastate both crops.

Frequently Asked Questions

Below are some frequently asked questions related to the topic of tomato plants, their suitable companions, and how to help them grow!

What should you not plant next to tomatoes?

The plants that can actually cause harm to your tomatoes are cauliflower, kale plants, brussels sprouts, broccoli, cabbage, and even kohlrabi. The reason is that although all of those plants are in the same family as your tomato plants, they will naturally compete for the same nutrients and growing benefits, causing the whole lot of them to be stunted instead of healthy!

Why should you not plant cucumbers next to tomatoes?

If you were planning on growing your salad ingredients next to one another, namely tomatoes near cucumbers, think again!

Cucumbers and tomatoes may taste great together, but the plants will fight one another for nutrients if planted too close together. They also suffer from mosaic virus, which cancels out fruit production.

Can I plant peppers with tomatoes?

You can choose to risk planting many kinds of peppers near tomato plants, especially because they benefit from the same growing condition requirements.

However, you will need to worry about the fact that both of these plants catch diseases like bacterial spot and verticillium wilt, as well as attract the same kinds of pests.

What marigolds grow well with tomatoes?

As detailed above, tomatoes benefit from marigold plants because marigolds are small but can repel the pests that would commonly love to plague your tomato plants. The best type of marigold for these purposes are French Marigolds.

Can zucchini and tomatoes be planted together?

The fruits of tomatoes and zucchini plants not only pair well together in many food dishes, but they also tend to thrive when planted near one another.

Just like some of the companion plants listed in our top 5 recorded above, zucchini plants can cover the ground of tomato plants safely and attract pollinating bees for the health of your tomato plant.

Should you plant basil with tomatoes?

Another great companion plant to consider cozying up to your tomato plant is basil. Basil actually benefits more from tomatoes, which have tall stalks and large leaves. The shade provided by these big leaf canopies provides moist, cool soil for basil to thrive in.

Can you plant tomatoes in the same place every year?

While you can choose to plant tomatoes in the same place every year because that spot may have great light exposure and temperate conditions, farmers actually warn against this pattern.

This is because after a tomato plant has occupied the same place for more than a year or so, the soil will start attracting more and more diseases and pests that are specific to that type of plant.

Does basil keep tomato worms away?

The worms that typically attack tomato plants are tomato hornworms, houseflies, aphids, asparagus beetles, mosquitoes and even white flies. However, each and every one of these pests, including the dreaded tomato hornworm, dislike the secretions of basil plants.

Therefore, the good news is that in addition to the tomato plant keeping the hot sun off of cool basil plants, the basil plant keeps detrimental bugs away from tomatoes!

How close should I plant marigolds to tomatoes?

Marigolds that are there for the pest prevention of the tomato plant should be planted around 24 inches, at most, from the plant stem.

This way, the marigold is close enough to warn off any pests but far enough away that the boisterous tomato plant can spread out and grow healthily.

Can I plant parsley with tomatoes?

Parsley is one of the most diverse companion plants, especially vegetables, that can be found in the plant world! The benefits that a tomato plant may get from having parsley nearby are no exception to that rule.

This is because aphids, beetles, and other creatures that would like to eat tomatoes are, in turn, hunted by hoverflies, which are attracted to parsley flowers.

Few Final Words

To sum it all up, tomato plants thrive not only when given growing conditions like full sunlight, an inch of water a week, and pH levels between 6.2 and 6.8 but when protected from pests by companion plants.

Companion plants like marigolds and borage can not only warn away pests but secrete nutrients from their roots that further help the tomato plant, either by boosting fruit production or killing off pests that are already infesting the plant.

Other companions, like carrots, can improve the soil quality of the tomato plant. In conclusion, companion plants are definitely something to use in your strategy to have a healthy, flourishing garden!