The Monarch butterfly (Danaus plexippus) captures the attention of gardeners across North America as it undertakes one of the world’s most remarkable insect migrations. Millions of these striking orange and black insects travel thousands of miles from their summer breeding grounds to overwintering sites in Mexico and California. Gardeners often seek to support this journey by creating habitats that offer both sustenance and a place for the next generation. Understanding which flowers provide the most effective support is paramount for a successful pollinator garden, requiring knowledge of the difference between a plant that fuels the adult and one that raises its offspring.
Do Monarchs Use Marigolds for Nectar
The adult Monarch butterfly relies on nectar from flowers to power its flight and will visit marigolds for this sugary fuel. Whether a marigold is a beneficial food source depends significantly on the specific variety planted. The butterfly uses its long, coiled proboscis to access the nectar deep inside the flower’s structure.
Highly hybridized marigold varieties, especially those with dense, double blooms, offer little value because their abundant petals physically obstruct the nectar. These cultivated forms make it difficult for the proboscis to access the flower’s center. Single-flowered varieties, such as French Marigolds (Tagetes patula) or the native Bur Marigold (Bidens species), are more accessible and are occasionally used as nectar sources.
Marigolds are generally not considered a high-value or preferred source of nectar, particularly during the demanding fall migration. Butterflies instinctively seek out flowers with high sugar content and easily accessible structures to maximize energy intake for the long journey. While a Monarch may sip from a single-petal marigold, the energy return is often less than that provided by other flowers.
The Role of Milkweed in Monarch Reproduction
The distinction between a nectar source and a host plant is the most important concept for supporting the Monarch population. While adult butterflies feed on numerous plant species, the Monarch caterpillar is a specialist with an obligate relationship with Milkweed (Asclepias species). The female Monarch will only lay her eggs on Milkweed because it is the singular food source for the emerging larva.
This dependence is a biological necessity rooted in the plant’s chemistry. Milkweed contains cardiac glycosides, a class of toxins poisonous to most vertebrates. The Monarch caterpillar sequesters these toxins into its body tissues as it consumes the leaves, making the caterpillar and the resulting adult butterfly unpalatable to most predators.
This specialized diet gives the Monarch its defense mechanism, signaled by its bright orange and black warning coloration. Any egg laid on a plant other than Milkweed will not survive, as no other plant provides this chemical defense. Supporting Monarch reproduction requires the presence of locally appropriate Milkweed species, which function as the sole nursery for the next generation.
Planting Recommendations for Monarch Support
Maximizing Monarch support involves selecting plants that address both the adult’s need for fuel and the caterpillar’s need for a host. The primary focus must be on planting Milkweed native to your specific region. A variety of species helps ensure a continuous supply of leaves throughout the breeding season.
Native Milkweed Examples
- Common Milkweed (Asclepias syriaca)
- Swamp Milkweed (Asclepias incarnata)
- Butterfly Milkweed (Asclepias tuberosa)
For adult butterflies, especially those preparing for migration, planting high-nectar, late-blooming native species is significantly more effective than relying on marigolds. Excellent choices include plants with composite flowers or dense flower heads, which provide a large, flat landing platform and concentrated nectar.
These plants offer concentrated energy critical for the autumn migration, where Monarchs must store enough fat to survive the winter. Annuals like Zinnias are also highly productive nectar sources and make a worthwhile addition. Focusing on these high-yield flowers ensures that Monarchs have the best possible chance to successfully complete their journey.
High-Nectar Native Examples
- Blazing Star (Liatris)
- Goldenrod (Solidago)
- Joe Pye Weed (Eutrochium)
- Native Asters (Symphyotrichum)