The perennial herb, Achillea millefolium, commonly known as yarrow, is a flowering plant found across the Northern Hemisphere. Though often considered a common wildflower or weed, yarrow is an excellent resource that draws in a diverse array of insects. Its ability to attract pollinators makes it a valuable addition to any habitat garden.
Why Bees Visit Yarrow Flowers
The structure of the yarrow flower heads makes the resources easily accessible to a wide variety of bees and other insects. Yarrow belongs to the Asteraceae family and produces composite flowers arranged in flat-topped clusters called umbels. These clusters are essentially a landing platform composed of many tiny individual florets.
Each small floret is relatively shallow, a structural feature that allows insects with short mouthparts, like many native bees and hoverflies, to easily reach the nectar. Unlike deep, tubular flowers that restrict access to long-tongued bees, yarrow’s open design welcomes generalist foragers. The flowers provide both nectar and pollen, the primary food sources for insects.
The tiny flowers are packed tightly together, allowing a pollinator to collect resources without needing to fly far. For a short-tongued insect like a sweat bee, this flat surface means it can remain relatively still while sipping nectar from multiple nectaries. The convenient morphology of the flower head and the availability of primary food sources make yarrow a highly efficient foraging stop.
Yarrow as a Reliable Pollinator Resource
Yarrow provides ecological utility because it often blooms reliably when other forage might be scarce. The plant typically flowers from early summer well into the fall, often peaking during the mid-to-late summer months. This timing helps bridge the “summer forage gap,” a period when many spring-blooming plants have finished their cycle.
The plant’s ability to thrive in tough conditions further enhances its reliability as a food source. Yarrow is highly drought-tolerant and can grow successfully in poor, well-draining soil, which means it continues to flower even when environmental stress causes other plants to fail. This resilience guarantees a consistent supply of nectar and pollen for pollinators throughout the season.
The flat, composite flower heads attract a broad spectrum of beneficial insects, not just honey bees. While honey bees visit yarrow, the plant is particularly attractive to smaller, native species. Researchers have documented over 15 different genera of native bees, including miner bees, digger bees, leafcutter bees, and sweat bees. The blossoms are also frequented by butterflies, wasps, hoverflies, and other beneficial insects like ladybugs.
Selecting and Growing Yarrow for Bees
Gardeners aiming to maximize pollinator support should be mindful of the specific variety of yarrow they choose. The native, single-flowered species, Achillea millefolium, typically features white or pale pink blossoms and offers the most accessible pollen and nectar. Many highly hybridized ornamental cultivars, which come in bright colors like deep red or yellow, often have reduced pollen or nectar availability.
Some ornamental varieties have been bred to have “double flowers,” where the pollen-producing stamens are replaced with extra petals, effectively making the plant useless to foraging insects. For the best ecological benefit, select the straight species or cultivars noted for their single-flower forms. The plant thrives best in full sun, requiring at least six hours of direct sunlight daily to produce abundant blooms.
Yarrow is low-maintenance, preferring well-drained, even sandy or loamy soil. It does not require fertilizer, which can cause the stems to grow weak and floppy. To ensure a continuous supply of flowers, deadhead spent blooms by cutting them back to a fresh set of leaves, promoting a second wave of flowering. Avoid the use of systemic pesticides, as these chemicals can be carried into the nectar and pollen, directly harming visiting bees.