Dahlias are popular garden flowers, prized for their variety in color, size, and form, providing vibrant blooms from midsummer until the first hard frost. For gardeners interested in supporting local ecosystems, a common question is whether these flowers serve as a food source for beneficial insects. The answer depends entirely on the specific variety and the resulting structure of its bloom.
Flower Structure and Pollinator Accessibility
The ability of a dahlia to provide sustenance to a bee or a butterfly is determined by the accessibility of its reproductive parts. A dahlia flower head, like others in the Asteraceae family, is composed of many tiny individual flowers, called florets. The showy, outer “petals” are technically ray florets, while the reproductive center is made up of disc florets. These disc florets contain the pollen and nectar that pollinators seek for food.
Most modern, cultivated dahlias have been bred to maximize ray florets, resulting in spectacular “double-flowered” varieties (e.g., decorative, ball, or pom-pom types). In these forms, the disc florets are either obscured or converted into additional layers of ray florets. This dense structure makes it physically impossible for insects, particularly bees, to reach the pollen and nectar sources.
Conversely, dahlias that closely resemble the original wild species are known as “open-centered” or “single-flowered” types. These blooms feature a prominent, flat, circular center composed of fertile disc florets that are fully exposed. A single ring of ray florets surrounds this exposed center, creating a clear, easy landing platform for visiting insects. The visibility and open access to the pollen-rich disc make these varieties highly attractive and beneficial to a wide range of pollinators.
Dahlia Varieties That Attract Pollinators
Gardeners seeking to use dahlias as a food source should focus exclusively on varieties with an open, accessible center. Single Dahlias are the most straightforward choice, featuring a single row of ray florets surrounding a clearly visible center of disc florets. The smaller Mignon Dahlias share this simple, open structure but are naturally more compact, making them excellent choices for container gardening.
Collarette Dahlias are highly effective, distinguished by a two-layered appearance. They have a single row of outer ray florets and a distinct “collar” of shorter, often differently colored petaloids encircling the exposed disc center. The open center remains fully available, and the contrasting colors of the collar guide visiting bees and butterflies.
Anemone Dahlias are attractive to larger bees due to their unique, domed center. This center is made up of elongated, tubular disc florets that form a fluffy, pincushion-like mound. This central mass is an accessible reservoir of pollen and nectar, making these varieties a favorite for foraging insects and providing valuable late-season sustenance.
Maximizing Pollinator Activity in the Dahlia Garden
Selecting the correct dahlia variety is the first step, but gardeners can employ several practices to encourage maximum pollinator visitation. Planting open-centered dahlias in large groups or “drifts” creates a significant visual target for foraging insects, signaling a substantial and dependable food source.
Maintaining a healthy environment is a major factor in supporting insect populations. Avoiding systemic pesticides is important, as these chemicals contaminate nectar and pollen, harming visiting bees and butterflies. Gardeners should rely on organic pest management and encourage natural predators to control problematic insects.
Providing a reliable water source, such as a shallow bee bath or damp soil, supports pollinator health. Companion planting with other attractors, like cosmos or zinnias, helps ensure a continuous food supply. Regular deadheading of spent open-centered blooms will prompt the plant to produce more flowers, prolonging the period of available pollen and nectar.