Here are some resources that are highly regarded as knowledgeable and reputable to help you answer your general plant and gardening questions.
Books: (click on images)
Sunset Western Garden Book (an essential guide, lists every species you can grow here)
The Ann Lovejoy Handbook of Northwest Gardening by Ann Lovejoy
Growing Vegetables West of the Cascades by Steve Soloman
Seattle Titlh’s Maritime Northwest Garden Guide– Available at PCC Markets
Northwest SmartGarden Regional Guides by the American Horticultural Society
Websites:
Elisabeth C. Miller Botanical Garden Great Plant Picks
(very popular, has a searchable database)
http://www.greatplantpicks.org/
Missouri Botanical Garden Plant Finder
(great easy to read information)
http://www.missouribotanicalgarden.org/plantfinder/plantfindersearch.aspx
Monrovia Nursery
(a go-to for the landscape industry)
Lady Bird Johnson Wildflower Center
(for Native plant searches)
https://www.wildflower.org/plants/
Portland Nursery
(Lots of in depth articles on specific plants for our region)
http://portlandnursery.com/
Garden Hotlines:
UW Botanic Gardens Plant Answer Line
(206) 879-5268
hortlib@uw.edu
Seattle Tilth Alliance’s Garden Hotline
(206) 633-0224
help@gardenhotline.org