Will loquat trees grow here in the Puget Sound, and which varieties are best?
In his book Trees of Seattle (2006), local author Arthur Lee Jacobson lists a small number of loquats growing in Seattle, all of them young trees. On his website, he at least mentions the potential for fruit if the winter flowers are not killed by frost. The book From Tree to Table: Growing Backyard Fruit Trees in the Pacific Maritime Climate (Barbara Edwards, Skipstone Press, 2011) says that loquat (Eriobotrya japonica) will grow well here as an ornamental tree, but it is extremely rare for it to produce fruit in USDA hardiness zones 8a and 8b (Puget Sound). (In warmer areas–zone 9 and 10–these are some of the recommended varieties: Gold Nugget; Champagne; McBeth; Big Jim.)
The website of California Rare Fruit Growers provides general information on growing loquat.