Milkweed planting for Monarch butterflies
What negative consequences might there be if I were to plant a "butterfly garden" to promote the survival of the Monarch butterflies. Particularly interested in milkweed varieties. What are "local" varieties of milkweed? I'm concerned about ordering milkweed seeds from the Eastern part of the US. My "butterfly garden would be in the vicinity of a Community Garden.
A Guide to the Native Milkweeds of Oregon gives you names and habitats of milkweeds native to Oregon. All of these serve as host plants for monarch larvae. Of these probably Asclepias speciosa, the showy milkweed, andAsclepias fascicularis, the narrow-leaved milkweed occur closer to the Portland area, so would be good choices. All milkweeds require well-drained soil, and when established will be drought-tolerant. The leaves are poisonous to us non-monarchs.
A source of seeds for these plants is given in this article The Monarch Butterfly from OSU. I would also suggest contacting your local nursery for availability of seeds and plants.
Monarch butterflies, Danau plexippus, have, of course, a fascinating life cycle. Migration and Overwintering, from USDA Forest Service gives a good view of both the Eastern and Western migration routes. Unfortunately on the western migration, most butterflies apparently fly up the east side of the Cascades, so we don't see too many in our area