Declines in pollinator populations and monarch butterflies require restoration of habitats with the plants and floral resources that support them. Monarch butterflies in particular lay their eggs exclusively on milkweed species, which their caterpillars require as a food source. Restoring populations of milkweeds can involve planting plugs grown from seed, but recommendations for breaking dormancy and germinating milkweed seeds often disagree. In a recent study published in AoB PLANTS, Kaye et al. tested the hypothesis that seed germination and dormancy vary within and among species of milkweed, and found substantial differences across species, and even between populations of the same milkweeds.
Kaye, T. N., Sandlin, I. J., & Bahm, M. A. (2018). Seed dormancy and germination vary within and among species of milkweeds. AoB PLANTS, 10(2). http://dx.doi.org/10.1093/aobpla/ply018