The decline in Monarch butterfly populations has driven many to seek ways to support this iconic species. Milkweed, belonging to the genus Asclepias, is the only host plant on which a Monarch butterfly will lay its eggs, making it necessary for the caterpillar’s survival. Without milkweed, the Monarch life cycle cannot be completed. Fortunately, this plant can be successfully purchased for cultivation in home gardens, providing a direct lifeline for the next generation of butterflies.
Sources for Purchasing Milkweed
Acquiring milkweed plants or seeds is possible through several channels, each offering a slightly different experience. Local nurseries and garden centers are a convenient option, but availability and variety may be limited to the most common species. It is helpful to call ahead to confirm their stock, as inventory can fluctuate throughout the growing season.
Specialized native plant nurseries, often run by conservation groups or smaller businesses, are better sources for a wider range of regional species. These vendors typically understand the ecological importance of local milkweed varieties and are more likely to offer plants grown without harmful chemicals. Organizations like Monarch Watch often provide online resources, such as the Milkweed Market, which supplies plants grown from seeds collected in specific regions.
Online seed and plant retailers offer the greatest variety, allowing gardeners to select specific Asclepias species suited to their climate and soil type. While ordering online is convenient, shipping can sometimes stress live plants, so selecting a vendor with good reviews and shipping practices is recommended. Community plant sales or seed swaps, often hosted by garden clubs or native plant societies, can also be excellent, low-cost ways to acquire locally adapted seeds and plants.
Essential Purchasing Considerations
The most important decision when buying milkweed is choosing a species native to your specific geographic region. There are over 100 species of Asclepias native to North America, and selecting a local variety, such as Common Milkweed (Asclepias syriaca) or Swamp Milkweed (Asclepias incarnata), ensures the plant aligns with the Monarch’s natural migration and breeding cycles. These native varieties naturally die back in the fall, which is a crucial part of the ecosystem’s health.
A significant concern is the widely available tropical milkweed (Asclepias curassavica), which is not native to most of the United States. In warmer climates, where it does not die back during the winter, the plant can harbor the protozoan parasite Ophryocystis elektroscirrha (OE). Caterpillars ingest the OE spores while feeding, leading to high infection rates in the resulting butterflies. Infected adults may emerge with crumpled wings, shorter lifespans, and reduced flight ability, hindering their long-distance migration.
The second consideration is verifying that the purchased milkweed is free of systemic pesticides, especially neonicotinoids. These insecticides are absorbed into the plant tissue, making the leaves lethal to Monarch caterpillars even at low doses. Caterpillars feeding on neonicotinoid-treated milkweed have lower survival rates and are significantly smaller and lighter than those on untreated plants.
It is essential to ask the vendor about their growing practices to ensure the plants are safe for Monarchs. A plant treated with systemic pesticides acts as an “ecological trap,” attracting butterflies to lay eggs on a food source that will ultimately kill their offspring. Focusing on certified organic or native plant nurseries is the safest way to ensure the health of the host plant.
Growing and Care After Purchase
Milkweed thrives in conditions that mimic its natural habitat, requiring relatively little specialized attention once established. Most species need a location that receives full sun, meaning at least six hours of direct sunlight daily. They generally prefer well-drained soil and do not require rich, heavily fertilized ground.
The initial planting phase is the most sensitive period, requiring consistent moisture until the roots become established. Once the plants are settled, they are quite drought-tolerant and should only be watered during extended dry periods. Overwatering can be detrimental, especially since many native species are adapted to drier conditions.
Milkweed is a perennial; the above-ground growth will die back in the fall and winter, a natural process. Leaving the dormant plant material provides winter cover and allows the plant to re-emerge from its taproot the following spring. Planting multiple plants in a cluster is recommended because it provides a more concentrated target for egg-laying butterflies and ensures enough foliage for hungry caterpillars.