Do you think calendula is just cute "marigolds" that heal wounds and decorate borders? No way!
This flower is a real saboteur in the plant world, capable of strangling weeds with its bare hands, but its secret war with dill will make you reconsider all the principles of gardening.
In 2023, the journal Organic Gardening published a study that blew up the internet: calendula roots secrete a substance called “calendene,” which acts as a natural herbicide, killing couch grass and chickweed by 90% in a season.
But there is one nuance that even experienced agronomists are silent about. Galina Kizima , author of the bestseller "Garden and vegetable garden without chemicals", compared the neighborhood of calendula and dill with a "quiet apocalypse": dill seeds do not germinate at all, and adult plants wither, as if they were poisoned.
The real story of Svetlana from Rostov went viral on TikTok: her dill bed turned into a desert while the calendula was blooming.
“I thought it was a fungus or pests, but a laboratory analysis showed that calendula flavonoids were to blame,” she said in the blog “Dachnye Sekrety.”
Scientists from the All-Russian Research Institute of Vegetable Growing confirm that these compounds block cell division in dill roots, and at the same time suppress the growth of even such tenacious weeds as quinoa. But how does it work?
The experiment of the channel "First Bed" gave the answer. In the area where calendula was planted between the rows of tomatoes, the harvest increased by 20%, and the whitefly disappeared in two weeks.
But in the neighboring bed, where calendula was next to dill, there were no shoots at all.
“It’s like chemical warfare,” commented leading agronomist Artem Lysenko .
But calendula is not always an enemy. It forms an ideal alliance with parsley, basil and carrots.
The blogger "Green Patrol" conducted an interesting experiment: he sowed calendula around a carrot bed - and did not pull out a single weed for the entire season. "The carrot roots became juicier, and the tops - brighter," he wrote in his Telegram channel. But with cilantro and celery, calendula behaves like a capricious neighbor: sometimes it helps, sometimes it harms.
It all depends on the variety. Dutch scientists from Wageningen University have found out that bright orange varieties of calendula are more aggressive than yellow ones. Their roots release 40% more toxins, but they repel the Colorado potato beetle better. But let's get back to dill.
Why can't they be reconciled? Laboratory tests have shown that dill seeds that have been lying next to calendula for a month lose 95% of their germination capacity.
“It’s like planting them in concrete,” jokes agronomist Mikhail Vorobyov in the “Garden Wars” podcast.
But there is a life hack from Canadian farmers. If you really want to grow dill next to calendula, plant it in containers with soil isolated from the general soil. Or sow dill in the fall, after the calendula has bloomed - its roots are less active by this time.
Another secret was revealed by the Japanese company “Takii Seed” , which developed a dill hybrid that is resistant to calendula.
But the seeds are only available in Asia for now. What about other crops? Experiments by British gardener Charles Dowding have proven that calendula planted next to potatoes reduces the risk of late blight by 30%. But its proximity to radishes is a disaster. The root crops grow small and bitter, as if they were doused with poison.
“Calendula draws selenium from the soil, which is critical for radishes,” explains Olga Chemarina, a doctor at the Moscow State University Botanical Garden.
But the most unexpected fact is that calendula can save your lawn.
In 2022, American YouTube gardener David Domoney posted a video in which he planted calendula in an area overrun by dandelions.
Within three months, the weeds were gone and the lawn was green without herbicides. “Calenden works better than Roundup,” he told The New York Times .
But remember: calendula is not called "marigold" for nothing. Its roots "scratch" the soil, disrupting the soil structure for sensitive crops. Therefore, it is better to plant green manure after it - for example, mustard. And one more piece of advice from old gardeners: never compost calendula stems.
Their toxins remain even after rotting and can ruin seedlings. Throw them in the trash or burn them. And if you want to "neutralize" the bed after calendula, water it with a solution of wood ash (1 glass per 10 liters of water) - the alkali will neutralize the remains of calendula.
And yes, dill is not the only victim. Arugula, spinach and even some varieties of lettuce also suffer from the proximity of this killer flower. So plan your beds wisely, and your calendula will become an ally, not an enemy.
