Monarch Nectar Plant Guide: Rocky Mountains
One of the most significant actions you can take to support monarch populations is providing nectar-rich flowers and milkweed host plants. Adult monarchs depend on diverse nectar sources for food during all stages of the year, from spring and summer breeding to fall migration and overwintering. Caterpillars, on the other hand, are completely dependent on their milkweed host plants. Inadequate milkweed or nectar plant food sources at any point may impact the number of monarchs that successfully arrive at overwintering sites in the fall.
Monarchs are in decline across their range in North America. Loss of milkweed host plants due to extensive herbicide use has been identified as a major contributing factor, and habitat loss and degradation from other causes, natural disease and predation, climate change, and widespread insecticide use are probably also contributing to declines.
While many guidelines are available regarding which species of native milkweeds are best for your region, monarch-specific nectar plant guides have not been available for large regions of the U.S. To address this need, the Xerces Society, in partnership with the Monarch Joint Venture and National Wildlife Federation, developed 15 regional lists for the continental U.S. These lists are geared toward gardeners and landscape designers but will also be useful for land managers who are implementing large-scale monarch restoration projects.
These nectar plant lists were compiled based on best available data and are considered working documents. You can help us improve them by submitting additional monarch nectaring observations submitted via our online survey. Note that not all species will work for a given site; we encourage you to use additional references when making final species determinations for your location.