NW milkweed

[Robert Thorn]

Common milkweed is very rare west of the Cascades.  It's not native and
doesn't like the moist climate, so it clusters around areas of some
human activity.  Look for it around old dumps (like Magnusen Park behind
 
the Sand Point Naval Station or the Renton Ponds) or along railroad
right-of-ways (like the Renton bikepath near where you live.  We always
use to ride along this path to examine the milkweeds, since it was one
of the more reliable spots for it around Seattle.)  Hope this helps.
 
Rob Thorn