Milkweeds are an essential component of the Monarch Butterfly life cycle as the sole food source for monarch caterpillars. While no Milkweeds are native to Portland there are two species native very close by in the Willamette Valley and throughout much of Oregon. One such species is Asclepias fascicularis or Narrowleaf Milkweed. As it's name suggests it has very fine narrow leaves and it blooms in Summer with umbel-shaped clusters of pink/white flowers. In addition to Monarchs it is also attractive to native bees such as green sweat bees.
One of the easiest milkweeds to grow in a garden due to its drought/heat tolerance as well as adaptability to seasonally wet conditions. Milkweeds have a reputation for being thugs in the garden spreading readily from rhizomes as well as by seed. This species spreads a bit less aggressively than many others. Milkweeds are deer and rabbit resistant likely due to unpalatable taste and toxicity. For the same reason care should be exercised when the space is shared by pets, however, it is unlikely to be consumed by pets in lethal quantities due to taste.
Size: 16"-36" tall x 10"-16" wide
Light: Sun
USDA Zone: 6a-10b