Marigolds, with their bright sunny blooms, defy the typical, easy withering fate of flowers. Often compared to the sun’s eye in poetry, they feature in cultures worldwide, and are particularly revered in India. From Varanasi’s street stalls to the temple steps of Tamil Nadu, these flowers—heaped or strung in garlands—honour both the living and the dead.
Growing them requires little care, and their flowering season lasts year-long. It’s a well-known piece of advice among farmers to plant marigolds alongside tomatoes, cabbage, and strawberries to keep plants safe.
Power of scent
Besides finding a spot in the cultural landscape, marigolds are also hard at work in fields. Their roots release a substance that chemically controls several species of nematodes (worm-like creatures) or invisible pests that feed on plant roots, stunt growth and often cause the plants to die. Marigolds are most effective in controlling the common meadow and stylet nematodes. In the first year of planting marigolds, they start repelling pests. In the second year, the leftover substances in the soil become even better at repelling. This effect can last into the third year, too.
Why do marigolds work for some who till the land, but not for others? Because the strength of their exudate depends on the variety. Another reason why marigolds are not suitable for every garden is that their roots produce a sulfur compound called thiophene, which cannot be handled by all plants, like roses.
With so much hybridisation, many of the plants’ basic characteristics have been altered, not least of which is the distinctive—and to some, offensive—odour. This smell of many hybrid marigolds is a natural insect repellent. Fascinatingly, marigolds have been grown at the border of rice fields at Uttarakhand’s Navdanya Biodiversity and Conservation Farm, to deter aphids, mosquitoes, nematodes and rabbits.
However, there are no absolute rules. Interestingly, not all insects are repelled by marigolds. For instance, Japanese beetles are drawn to their scent. In this case, marigolds can be strategically used as trap crops to lure beetles away from more vulnerable plants.
Calendula officinalis (Credit: Wikimedia Commons)Two types of marigold commonly available are French marigold (Tagetes patula) and pot marigold (Calendula officinalis). While French varieties are often toxic (to both humans and pests), pot marigolds are edible and can be used in salads or as a natural food colouring. Since they are similar in appearance, understanding which variety to use when and where is crucial.
Also read: These ducks mean business in paddy fields
A multipurpose bloom
Marigold’s sagey scent can also be used as a homemade insect spray, as an alternative to stinkier ones. Here’s a simple DIY method:
- Crush large amounts of marigold flowers, including roots and leaves, and soak them in a bucket of water.
- Let the mixture ferment for 5-7 days, stirring daily.
- Once decayed, strain through a cloth and save the liquid.
- Dilute the liquid with an equal part of soft, potash-based soapy water (avoid modern detergents with caustic soda, which may burn plant leaves and deplete soil fertility when used frequently).
Pro Tip: Add coriander to the mixture to deter pests that might otherwise be attracted to the marigolds themselves. Be cautious when spraying, as marigolds can attract bees.
Also read: The surprising culinary uses of jasmine flower
More uses
- Mulch: Use decayed marigold leaves, stems, and flowers as mulch to suppress pests.
- Interplanting and rotation: Planting marigolds between crops or rotating them through nematode-infested soil can naturally clean the soil and protect future plantings.
- Pollinator and beneficial insect magnet: The Tagetes species of marigold attract helpful insects, promoting a balanced and healthy ecosystem.
Intercropped coconuts with marigolds (Credit: Wikimedia Commons) Easy to plant
Marigolds can serve as a companion, especially since many bedding plants don’t handle transplanting well once they bloom. One of the marigold’s standout qualities is how easily it adapts to newer settings. Unlike many flowering plants, it can be transplanted with ease even when in full bloom. Whether they are moved from garden beds into containers, or brought indoors, they adjust with minimal fuss and continue to thrive.
They’re not picky about soil either. While marigolds will grow in almost any type of soil, they do best in well-drained, compost-rich soil under full sunlight. Adding a bit of compost or aged manure can give them an extra boost. When transplanting, keep them at the same soil level as before, press the soil firmly around the base, and water thoroughly. More often than not, the plants won’t miss a beat and will look like they’ve always been there naturally.
Despite being frost-sensitive with a propensity to turn brown at temperatures below 0°C, marigolds are able to adapt for much of the growing season. If it were not for the nursery industry's constant development of flamboyant new hybrids, they may have been seen as vivid weeds.
Also read: Why neem oil is the OG pest buster
(Banner image credit: Neerja Deodhar)
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