Dahlias are celebrated flowers in the late-summer garden, prized for their variety of colors and forms. As gardeners seek to create beautiful spaces, they also hope to attract desirable wildlife like butterflies. Whether these popular flowers offer genuine sustenance depends entirely on the specific flower structure of the variety planted.
Flower Anatomy: Why Access is Key for Butterflies
The success of a dahlia as a butterfly food source hinges on the accessibility of its central disc florets, which are the reproductive parts that produce nectar and pollen. Dahlias belong to the Asteraceae family, meaning their large flower head is actually a composite of many tiny individual flowers. For a butterfly to feed, it must be able to easily reach the nectar deep inside these central tubes using its long, specialized proboscis.
Modern dahlia breeding has heavily favored “show” varieties, such as dinnerplate, pompon, and cactus types, which feature densely packed, layered petals. This process converts the flower’s central disc florets into extra ray florets, effectively turning the center into more petals. The resulting double-flowered structure completely obscures the nectar and pollen sources, making it nearly impossible for a butterfly to access food. The layers of tightly curled or folded petals act as a physical barrier.
In contrast, the original wild dahlia species was a simple, single-flowered bloom with a clearly visible open center. These simpler varieties retain the open architecture that allows butterflies to land on the broad ray petals and walk directly onto the exposed disc florets. This easy access is important, as butterflies prefer a highly visible, readily available nectar source. Therefore, a dahlia’s value to a butterfly is inversely related to its petal count.
The Best Dahlia Choices for Nectar and Pollen
To successfully support butterflies, gardeners should specifically look for dahlia types that maintain an open, visible center. These varieties are often described with terms like “single-flowered” or “open-center” and closely resemble the daisy-like form of the wild species. The single dahlia has one ring of ray petals surrounding a clear, prominent disc of pollen-rich florets, which is perfectly suited for a butterfly’s feeding behavior.
Other beneficial flower types include Collarette and Anemone dahlias, which still offer accessible centers despite having slightly more complex petal structures. Collarette dahlias feature a ring of smaller, frilly petals, called the collar, situated between the outer petals and the central disc. Anemone-flowered dahlias have a dense, pincushion-like center of tubular florets that is open and highly attractive to pollinators.
Specific cultivars excellent for butterflies include the ‘Bishop’ series, such as ‘Bishop of Llandaff,’ which pairs dark foliage with open, scarlet flowers. The ‘Happy Single’ series, including varieties like ‘Happy Single Romeo,’ are also reliable choices due to their open-centered structure. Selecting these simpler forms ensures the dahlias provide both vibrant aesthetics and valuable sustenance for garden visitors. When purchasing, look for varieties labeled as “pollinator-friendly” to ensure the reproductive parts are not hidden.
Essential Elements of a Butterfly-Friendly Garden
While choosing the correct dahlia type is important, an effective butterfly garden must offer more than a single nectar source. Butterflies require a complete habitat that supports all stages of their life cycle, from egg to adult. This comprehensive approach ensures the garden acts as a sanctuary, not just a temporary feeding stop.
A crucial component is the inclusion of host plants, which are the specific vegetation species that caterpillars must eat to survive. For example, Monarch butterflies rely solely on milkweed plants for reproduction. Planting a variety of host plants tailored to local butterfly species encourages females to lay eggs and ensures the next generation can develop.
Adult butterflies need consistent access to nectar from early spring through late autumn to fuel their flight and migration. Dahlias bloom late in the season, making them a great resource when many other flowers have faded. They should be complemented by other elements to create a full habitat:
- Consistent nectar sources, including early and mid-season plants like zinnias, asters, and coneflowers.
- A shallow water source, such as a damp patch of soil or a “puddling” area, allowing butterflies to extract necessary salts and minerals.
- A sunny location with sheltered areas to provide protection from wind and predators.
- A microclimate where butterflies can safely bask, feed, and rest.