Marigolds (Tagetes) are popular annuals prized for their cheerful, warm-toned blooms in shades of yellow, orange, and red. Gardeners often plant them to attract beneficial insects, but their effectiveness as a pollinator plant is not simple. Whether these vibrant flowers attract bees and butterflies depends heavily on the specific variety being cultivated.
Marigolds and Pollinator Attraction
Marigolds are visited by insect pollinators, including bees and butterflies. Their bright colors, particularly yellow and orange, act as visual signals drawing insects to the flowers. Pollinators seek pollen and nectar for survival and energy; bees seek protein-rich pollen for their young, while butterflies focus on sugary nectar.
However, not all marigolds offer these resources equally. Many hybrid varieties have been selectively bred for aesthetic traits that inadvertently reduce their value to insects. Varieties featuring a simple, single layer of petals with an open center are the most effective, providing easy access to the plant’s reproductive structures. For instance, Signet marigolds (Tagetes tenuifolia) with small, single blooms are known to be excellent at attracting bees.
Why Flower Structure Matters
The physical structure of the marigold bloom determines its usefulness to pollinators. Wild or heirloom marigolds exhibit a single-petaled structure where the reproductive parts, including pollen-bearing anthers and nectar sources, are clearly visible and easily reached. This open design allows insects to land and quickly gather the necessary resources.
Many modern cultivars, such as the large African marigolds (Tagetes erecta), have been bred to be “double-flowered.” This trait causes the stamens (male pollen-producing organs) to mutate into extra petals, creating a dense, pom-pom shape. The mass of petals physically blocks access to the limited remaining pollen and nectar deep within the flower head, making it nearly impossible for a bee or butterfly to reach. While these double blooms are visually appealing, they are functionally useless to most visiting insects.
Marigolds as Natural Pest Deterrents
The reputation of marigolds is often equally tied to their ability to deter garden pests, a context that also influences pollinator visits. The roots of certain Tagetes species release a chemical compound called alpha-terthienyl into the soil. This substance is toxic to root-knot nematodes, microscopic worms that damage plant roots. By interrupting the nematode life cycle, marigolds help protect nearby plants from this common soil pest.
The foliage also contains volatile organic compounds, like limonene, which contribute to their strong, pungent aroma. This powerful scent is thought to confuse or repel certain above-ground pests, such as whiteflies, by masking the odor of their preferred host plants.
Tips for Boosting Pollinator Visits
Gardeners aiming to maximize pollinator activity should prioritize selecting single-flowered marigold varieties with clearly exposed centers. French marigolds (Tagetes patula) and Signet marigolds are the best choices, especially non-hybridized types that offer accessible pollen and nectar.
Planting marigolds in large, concentrated clusters, known as mass planting, makes them more visible to passing bees and butterflies. A large patch of color acts as a strong beacon, directing pollinators to the resource-rich area. Combining marigolds with other high-attraction flowers, such as salvia or lavender, further increases the garden’s appeal. Ensuring a mix of open flowers throughout the season provides a continuous food source.