Chrysanthemums, commonly known as mums, signal the arrival of autumn with their vibrant colors. These prolific bloomers are a popular choice for gardeners seeking color when most other flowers have faded. Do these widely available fall flowers provide value to foraging bees and other pollinators? The answer depends entirely on the specific flower structure of the plant.
The Varying Attractiveness of Mums to Bees
The attractiveness of a chrysanthemum to a bee is determined by its flower form, which falls into two main categories: single and double-flowered varieties. Single or semi-double mums, which resemble daisies, are generally beneficial to pollinators. These varieties feature an open center where the reproductive parts, or disk florets, are visible and accessible. These exposed central florets produce the pollen and nectar that bees seek for late-season foraging.
Most densely petaled mums sold commercially are the double-flowered types, which are not useful to bees. These cultivars have been bred for ornamental density and long-lasting blooms, often at the expense of their biological function. The typical decorative variety offers little to no accessible food source for visiting insects.
The Impact of Flower Structure on Pollinator Access
The difference in value between mum varieties is a direct result of selective breeding. Naturally occurring chrysanthemums have a simple, open structure featuring ray florets (petals) surrounding central disk florets that contain pollen-producing stamens. Plant breeders selected for a genetic mutation that converts these fertile stamens into additional, non-reproductive petals. This process results in the full, fluffy appearance of double-flowered mums, where the center of the bloom is completely obscured by dense layers of petals.
This physical transformation creates a significant problem for foraging insects. The layers of extra petals not only reduce the amount of pollen produced but also bury the nectaries. For a bee, the flower’s resources are either nonexistent or completely inaccessible, hidden deep beneath a profusion of petals. A bee may expend valuable energy investigating these double blooms, only to find the flower offers no reward.
Essential Alternatives for Late-Season Bee Forage
Since many popular chrysanthemums are poor food sources, gardeners can provide better support for bees by planting high-value alternatives that bloom late in the season. Providing these open-structured flowers ensures that bees have the consistent food supply of carbohydrates and protein needed to survive the winter.
Several high-value alternatives are available for late-season bee forage:
- New England Asters and Goldenrod offer copious amounts of both nectar and pollen when resources are dwindling.
- Sedum, particularly the variety ‘Autumn Joy,’ produces dense heads of pink to reddish flowers highly attractive to pollinators.
- Japanese Anemones are beneficial, offering open, accessible blooms late into the autumn.
- Open-pollinated or heirloom varieties of sunflowers provide substantial pollen, unlike many commercial cultivars bred for seed production.