You probably already know dynamic duos like peanut butter and jelly, milk and cookies, or macaroni and cheese, but did you know that marigolds and tomatoes go together, too?
In addition to making your garden more beautiful, marigolds may be able to help your tomato plants survive and thrive!
Keep reading to learn more about what makes tomatoes and marigolds the perfect pair.
Planting Marigolds and Tomatoes Together
Learning how to plant tomatoes and marigolds in the same area is easy if you pay attention to the unique steps it takes to mix these two plants together.
Marigolds and tomatoes have a symbiotic relationship, which means that they will actually benefit one another if they are planted close together in the correct way.
The first aspect to consider is when to plant each specific type of seed. Many experts recommend that you should plant tomatoes first, and then add the marigolds soon after.
However, it’s important that you don’t wait too long between planting your tomatoes and marigolds! If the tomato plants grow faster than the marigold plants, then the marigolds may not be able to protect the tomato plants as effectively.
When planting your marigolds, dig a hole and place the marigold plants approximately 12 – 18 inches apart from the tomato plants.
This amount of distance will ensure that all the plants have enough room to grow but that the marigold plants aren’t too far away to be effective.
Aside from the spacing, you have a little flexibility to determine where exactly the marigold plants should go!
Specifically, marigolds can go between the tomato plants or around them in a little border. You can even do both if you’re aiming for maximum protection. Whatever you’d prefer to do works!
At this point in the process, it also might be helpful to surround each tomato plant with a tomato cage for extra protection and support.
To prevent your garden from getting too crowded, be sure to thin the marigolds after they’ve gotten two or three inches tall.
Once they’re planted, watering tomato plants and marigold plants simultaneously is totally okay. Just be sure to water the soil directly rather than watering them overhead to prevent the leaves from rotting or becoming diseased.
For everything you need to know on getting your marigolds started, read our blog post, How to Plant Marigolds.
Why Do Marigolds and Tomatoes Work Together?
There are many benefits to planting marigolds and tomatoes in the same area. While some of these benefits may seem slightly obvious, others might surprise you!
Attracting Pollinators and Other Insects
Marigolds are great at attracting pollinators and other types of insects that will make your tomato plants happier and healthier!
For example, marigolds are favorites of honeybees, wasps and other types of bees.
Ladybugs, moths, and butterflies are also fans of marigolds.
Bees and butterflies can pollinate the tomato plants, while ladybugs keep many varieties of pests away from your growing tomatoes.
In addition to actively helping the tomato plants, these insects can also assist in keeping away harmful organisms from your tomatoes!
For example, the different types of wasps that marigolds attract can help tomato plants in different ways. Specifically, paper wasps act as pollinators for tomato plants, while parasitic wasps keep tomato hornworms at bay.
To do this, parasitic wasps lay eggs on top of tomato hornworms. The eggs attach to the hornworm’s back, and once they hatch, the wasp larvae steal all of the tomato hornworm’s nutrients. This eventually kills the tomato hornworm.
Tomato hornworms are some of the most harmful insects to tomato plants. They quickly remove leaves from tomato plants and destroy the tomatoes themselves.
Without predators like the parasitic wasp intervening, tomato hornworms could easily decimate your carefully grown tomato crop!
Marigolds serve as a “trap crop,” which means that they attract insects and other animals that would otherwise harm the tomato plants.
Instead of heading straight to the tomatoes, these animals eat the marigold plant, which keeps the tomatoes protected and free of holes or other blemishes.
Specifically, marigolds can work as a trap crop for snails and slugs, which are known for their attraction to tomatoes.
Spider mites also like to eat marigolds, so in some cases, marigolds can serve as an effective barrier against spider mites, too.
While they’re great at attracting some animals, marigolds are also fantastic at repelling other animals! This benefit means that marigolds can keep themselves safe and also keep tomato plants safe from certain predators.
For example, marigolds release a chemical called limonene that has been proven to keep whiteflies away. Whiteflies are smaller insects that typically attach themselves to the bottom of plant leaves.
In addition, many gardeners say that marigolds’ strong scent can keep away aphids, thrips, tomato hornworms, rabbits, and even deer.
For the smaller insects on this list, marigolds also attract predators that will harm them.
Especially Root-Knot Nematodes
Finally, marigolds keep root-knot nematodes away. Root-knot nematodes are long, worm-shaped insects that burrow into soil or plants and may become parasites for the plants they attach themselves to.
They can also make holes in a plant’s roots which leave those plants susceptible to disease-causing bacteria and fungi that enter through those holes.
Marigolds keep root-knot nematodes away by stopping nematode eggs from developing by releasing a chemical called alpha-terthienyl.
Deadheading marigolds and incorporating them into the soil can also help keep root-knot nematodes away. Gardeners deadhead marigolds by cutting off dead and dying flowers so the plant will continue to bloom.
After cutting the flower off of the plant, break the flower into pieces with the help of a shovel and incorporate it into the soil. Doing this will maximize your chances that nematodes will stay away from the plant and surrounding soil.
Promoting Soil Health
In addition to keeping pests at bay by stopping the growth of nematode eggs, marigolds also promote overall soil health by killing fully-grown root-knot nematodes.
While we don’t know for sure scientifically speaking, marigolds might use toxins to trap nematodes and kill them. This means that they don’t have the opportunity to grow or produce any more eggs.
Preliminary scientific studies haven’t shown that marigolds can directly prevent or eliminate diseases that harm tomato plants. However, studies have shown that an extract made from one specific marigold variety does have anti-fungal properties.
That said, marigolds don’t cause or pass on any diseases to tomato plants, so it’s worth giving them a try, even if we’re not sure if they directly prevent disease!
FAQs About Tomatoes and Marigolds
Where can I grow marigolds and tomatoes?
You can grow tomatoes and marigolds pretty much anywhere! All you need to worry about is that they’re placed somewhere with adequate sunshine for them to grow.
As previously mentioned, you can intersperse marigold plants with tomato plants or you can plant marigolds in a circle around your tomato plants as a protective barrier.
However, there’s also great flexibility in the exact location where you plant your marigolds and tomatoes.
Marigolds and tomatoes grow well on the ground in a raised bed or planter and up in the air in a hanging pot. This means that if you don’t have a ton of room for planting, you can still make your tomatoes and marigolds work!
Do different marigold varieties exist?
Yes, they do! More than 50 species of marigolds exist today.
In fact, each marigold variety has slightly different characteristics that will benefit tomatoes in various ways.
For example, the Signet marigold is particularly good at attracting pollinators.
In addition, two marigolds varieties are especially known for their effectiveness as deterrents. Specifically, the African marigold is good at deterring deer, and the French marigold is a more effective deterrent of root-knot nematodes.
The African marigold also grows the tallest out of all the marigold varieties. It typically stands anywhere from one foot to three feet tall when fully grown.
Because of the African marigold’s height, it might make sense to plant this specific variety around the perimeter of your tomato plants rather than in the middle of them. They’d make a great protective border around your garden!
Does science support mixing marigolds and tomatoes?
Scientific research in the area of companion planting marigolds and tomatoes is still developing, so not all the benefits listed above have been scientifically confirmed.
One benefit of planting marigolds and tomatoes that has been scientifically confirmed, though, is marigolds’ ability to prevent whiteflies.
Regardless, something that we know for sure is that tomatoes and marigolds don’t harm one another! Therefore, given the benefits many gardeners have experienced, it makes sense to give this method a shot.
Learning to Grow Tomatoes and Marigolds
The next time you think about planting some tomato seeds in your garden, consider adding marigolds to the mix! They might be the difference between ripe, juicy tomatoes and small, unhealthy ones filled with holes from insects and other pests.
If you’re curious to learn more about other ways to grow and care for tomato plants, check out our Tomato Plants page for more gardening tips and tricks!