Every year, as monarch butterflies embark on their incredible migration, gardeners and nature enthusiasts are faced with a recurring debate: Should you plant tropical milkweed Asclepias curassavica in your garden? Despite some controversy surrounding the tropical milkweed, it’s time to look at the facts and assess why this plant is not only beneficial but essential under certain circumstances.

Understanding the Controversy

Tropical milkweed has gained popularity due to its vibrant colors, its ability to attract monarchs for feeding and reproduction, and its ease of propagation. However, it often faces criticism for two main concerns: its potential to host harmful protozoan parasites (OE) and its ability to disrupt monarch migration patterns. But how valid are these concerns?

The OE Parasite Issue

The assertion that tropical milkweed contributes to the spread of OE (Ophryocystis elektroscirrha) parasites is only a significant concern in regions where the plant does not die back in winter. In areas where tropical milkweed perennializes, the continuous leaf matter can indeed foster higher levels of these parasites. However, this issue is easily mitigated by cutting back the plant in late fall, effectively breaking the parasite’s lifecycle and minimizing risk. In fact, for about 90% of the United States where winter temperatures naturally control plant growth, this is a non-issue.

Migration and Breeding Cycles

The fear that tropical milkweed might confuse monarchs into breeding out of season rather than continuing their migration is also largely unfounded. Studies, including those by Dr. David James, a research scientist and entomologist at Washington State University, have shown that monarchs are triggered to migrate by a combination of decreasing daylight and cooler temperatures, not merely the presence of milkweed. Thus, the presence of tropical milkweed does not inherently cause monarchs to halt their migratory journey.

The Advantages of Planting Tropical Milkweed

Given its ease of growth and the attractiveness to monarchs, tropical milkweed can play a crucial role, especially in urban and suburban settings where native varieties may be less available. It serves as an excellent food source for monarchs, particularly in early spring and late fall when native milkweeds might not be available.

Planting Responsibly

While planting tropical milkweed has clear benefits, it is essential to do so responsibly:

• Cut Back in the Fall: In warmer climates, trim back milkweed plants in the fall to reduce the risk of OE.
• Diversify with Native Milkweeds: Alongside tropical milkweed, plant native milkweed varieties. Native plants offer the best overall support for local ecosystems and wildlife, including monarchs.
• Be cautious with insecticides: Avoid using insecticides near these plants and ask the garden center you purchase from if the milkweed has been treated with pesticide.

Encouragement Over Criticism

Encouraging the planting of any milkweed—tropical or native—is crucial for supporting monarch populations. The persistent sharing of articles discouraging tropical milkweed often deters enthusiastic gardeners who could be helping monarchs. Instead of dissuading, we should educate on proper planting and management practices that ensure the health of both the plant and butterfly populations.

In conclusion, while it is vital to continue planting native milkweed species, dismissing the benefits of tropical milkweed could do more harm than good. By understanding the actual risks and managing them effectively, gardeners can make informed decisions that support the health and migration of monarch butterflies. Let’s spread the word based on science and practical advice, not unfounded fears.

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