Have you heard of companion planting? Chances are, as a gardener, you’re already familiar with the concept. But just in case, companion planting is when you grow two or more plants together for mutual benefit.
More research is needed to determine whether companion planting actually creates mutually beneficial relationships between plants, but the practice has been passed down through the generations. So what is the harm in trying, either way? One example of a great companion plant combination is tomatoes and marigolds. Here are five reasons why.
1. Marigolds attract beneficial insects
Marigolds are a popular choice for gardens, and for good reason. These vibrant flowers not only add colour and life to your garden, but they also help to attract beneficial insects.
Ladybugs, for example, feed on garden pests like aphids, helping to keep your plants healthy. Lacewings, parasitic wasps, hover flies, and damsel bugs are also attracted to marigolds, and these bugs prey on various harmful insects.
Bees will be compelled to visit your marigold blooms as well, and we all know how important bees are for the health of your garden (and the entire world, to be honest.) In particular, signet marigold varieties will attract tons of bees.
2. Marigolds might repel some pests & can be used for trap cropping
According to some, the strong scent of marigolds can help to mask the scent of other plants that might attract pests. Deer and rabbits may avoid garden areas where you plant marigolds, but more data is needed to be sure.
Marigolds don’t repel as many pests as we’ve been led to believe, but they do attract at least 15 common garden pests, making them a viable trap crop. Trap cropping is the practice of planting one crop (the trap crop) specifically to lure pests to it so that your main crops can slide through the season pest-free. Here are some of the pests marigolds attract:
- Asiatic Garden Beetle;
- Blister Beetles;
- Cyclamen Mite;
- Garden Flea hopper;
- Greenhouse Leaf Tier;
- Japanese Beetle;
- Lygus Bugs;
- Potato Leaf hopper;
- Root Aphids;
- Six-Spotted Leaf hopper;
- Spider Mites;
- Stalk Borer;
- Yellow Woolly bear Caterpillar.
3. Marigolds suppress nematodes & repel hornworms
Marigolds release a compound that is toxic to root-knot nematodes and similar soil-dwelling, microscopic pests. This is huge because these nematodes can feed on the roots of your tomato plants and cause them to swell up and sustain significant damage.
You can suppress nematode numbers by growing lots of marigolds in the area where you plan to grow tomatoes, beans, or cucumbers. Some gardeners utilise a cover-cropping approach when using marigolds to address nematode issues. It’s recommended to try 300 plants per 100 square feet to accomplish this.
Some varieties of marigolds protect plants from root-knot nematodes more effectively than others. Recommended varieties include Bolero, Bonita Mixed, Goldie, Gypsy Sunshine, Petite, Petite Harmony, Petite Gold, Scarlet Sophie, Single Gold, and Tangerine. (List from Arizona Cooperative Extension).
Marigolds can also help you avoid losing tomato plants to the infamous tomato horn worm. Horn worms are green caterpillars that turn into sphinx moths. They much through tomato foliage and fruits with reckless abandon and are notorious for their ability to work through an entire tomato plant in a day or two if they go unnoticed. Planting marigolds around your tomato plants works to protect them somewhat from tomato horn worms.
4. Marigolds are easy to grow
Marigolds are reasonably easy to grow and don’t come with a lot of garden drama. The plants perform best in full sunshine, like tomatoes, and need at least six hours of direct sunlight. Add composted organic matter, fertiliser with phosphorous, and, if necessary, soil sulphur to create fertile soil for a vegetable crop. Use nitrogen lightly with marigolds. Excess nitrogen will result in a lot of foliage and few blooms.
Marigolds can be grown easily from seed, but you can commonly buy them as nursery transplants if you don’t want to plant seeds yourself. They are low-maintenance plants with a long flowering period, so you’ll be able to enjoy stunning yellow and orange blooms all summer long.
5. Marigolds produce tons of seeds
Marigolds are inexpensive in small quantities, but for those who want to try using them as a bulk trap crop or cover crop to target nematodes, marigold seeds can be expensive to buy in bulk. That being said, they are heavy on seed production. After your initial rotation of marigolds, you can collect enough seeds to become self-sufficient in marigold seeds and never have to buy them again.
To collect marigold seeds, try adding a nylon stocking or mesh bag over the top of spent marigold blooms so that seeds don’t blow away in the wind. Then, come through and collect the seeds at the end of the season. Store your seeds in a cool, dry place away from direct light. Seeds are generally good for several years when kept correctly
More information on companion planting
Marigolds aren’t the only companion plant perfect for pairing with tomatoes. Regarding companion planting, there are a few things to keep in mind. Make sure you choose plants that have somewhat similar watering needs. Or account for those differences and space out your plants accordingly. For example, tomatoes love water, while most herbs prefer to be on the drier side.
Consider what each plant offers in terms of nutrients, too. Tomatoes are heavy feeders, so you’ll want to choose plants that can add nitrogen or other essential nutrients to the soil. Pay attention to the size and growth habit of each plant. You don’t want anything that will crowd out your tomatoes or shade them from the sun.
It’s important to recognise, too, that companion planting isn’t necessarily recognised as credible by experts. Jim Schmidt, a horticulture specialist at the University of Illinois Cooperative Extension service remarks, “We have run numerous tests on companion gardening and in some cases have found that some plants with companions attract more insects than those that are planted by themselves“.
The only reason I bring this up is that companion planting can take a lot of time and effort to plan out in a way you feel happy with. Diversity in the garden is always good since strictly mono cropping can lead to many issues. If you personally find that companion planting has minimal returns for your garden, try not to cling to ideas that don’t work for you. But if you do find that companion planting has proven successful for you, do whatever you feel is best!
With all that in mind, here are a few more companion plants for tomatoes:
- Bush beans;
And while we’re on the topic, read about the top seven garden veggies and herbs to avoid planting near your tomatoes.
Types of marigolds to plant with tomatoes
Marigolds are a staple in many vegetable gardens, making them an excellent companion plant for tomatoes. They also grow in most gardening zones worldwide since they thrive in US zones 2-11, which spans quite a range of climate conditions.
Two of the most popular types of marigolds to plant with tomatoes are French marigolds, Signet marigolds, and African marigolds. French marigolds are smaller than African marigolds, but they are more aromatic. Here are some specific, popular marigold cultivars to try growing:
- Inca 2;
- Lemon gem;
- Colossus Red;
- Orange Flame;
- Kilimanjaro White;
- French Fireball.
All types of marigolds attract beneficial insects to the garden and help deter destructive pests like tomato hornworms. In addition, marigolds release compounds that help to suppress the growth of harmful bacteria in the soil.
How to plant marigolds to protect tomato plants?
FAQ about Growing Marigolds with Tomatoes
When to plant marigolds with tomatoes?
If you’re interested in companion planting with marigolds and tomatoes, it’s a great idea to know when to plant each. Marigolds should be planted after your area’s last frost date, typically in late April or early May. On the other hand, tomatoes should be planted about two weeks after the last frost date. If you’re unsure when the last frost date is in your area, you can check online or ask your local nursery.
How close should I plant marigolds with my tomatoes?
When planting marigolds with tomatoes, space them out about 18 inches away from tomato plants. This will give each plant enough room to grow without crowding the other.
Do I need to replant marigolds every year?
Marigolds are annuals, but they readily produce seeds. Once established, they can often reseed themselves and come back year after year. You will need to replant them yearly for smaller plantings, more deliberate plantings, or considerable cover cropping efforts.
Is growing marigolds difficult?
Not really. Marigolds are one of the easiest flowers to grow – I had success with them on my first attempt. Marigold seeds sprout quickly and are ready to be transplanted into the garden within a few weeks. They don’t need to be treated with special care or fertilization method – just keep them watered at the same rate as the rest of your garden once they’re established.
Do I need to deadhead my marigolds?
Yes, you should remove the spent flowers (deadheading) from your marigolds to encourage continued blooming. Deadheading also helps to tidy up the appearance of your plants. To deadhead, simply snip off the flower heads at the base with a pair of sharp scissors.
What are the best conditions for growing marigolds?
Marigolds prefer full sun and well-drained soil. They are quite drought tolerant, so you don’t need to worry about over-watering them. Too much water can lead to fungal diseases in marigolds. Marigolds should do just fine in most gardens as long as you give them plenty of sun and don’t water them too often.
Do I need to fertilise my marigolds?
No, you don’t need to fertilise your marigolds. Over-fertilising can actually damage the plants. If you feel that your marigolds are not blooming as much as you’d like, simply deadhead them more often to encourage continued flowering.
Due to the increased concern about pesticides’ adverse effects on humans and other organisms, as well as pests evolving resistance to common pesticides, there is now more significant interest in non-chemical pest management methods. Marigolds not only add beauty to your garden but also act as an effective natural pesticide.
Overall, companion planting marigolds with tomatoes can benefit your garden. Marigolds help to attract beneficial insects, suppress root-knot nematodes, and are easy to grow. In addition, marigolds are beautiful and relatively inexpensive. If you’re interested in trying companion planting in your garden, marigolds and tomatoes are a great combo to start with.