Oregon has a wide range of climates from USDA Zone 4 to 9, with the warmest areas in the west by the ocean and the cooler areas to the east. Pick a shade tree that is hardy in your area with the type of needed shade. Tall trees with a dense crown will provide full shade, and trees with a loose crown will provide the filtered shade that some plants need to grow in.
Common alder (Alnus glutinosa), also known as black alder and European alder, is a member of the Betulaceae family. The tree is deciduous, growing 40 to 60 feet tall and 20 to 40 feet wide. Dark-green round leaves grow 2 to 4 inches long and 3 to 4 inches wide. The common alder's flowers grow in clusters 2 to 4 inches long and are followed by egg-shaped nutlets that reach maturity in October. Plant common alder in full sun or partial shade and a moist soil. The tree is hardy in USDA Hardiness zones 4 to 7 in Oregon.
Asian White Birch
Asian white birch (Betula platyphylla) is a member of the Betulaceae family and is hardy in USDA Hardiness zones 4 to 8 in Oregon. The tree is deciduous, grows 40 to 50 feet tall and features dark-green deciduous leaves that measure up to 3 inches long and turn yellow in the fall. Tiny flowers bloom in April, growing in long clusters and are replaced by small nutlets. Plant Asian white birch in full sun and a moist soil.
Franklin tree (Franklinia alatamaha), also known as Franklinia, is a member of the tea family. The tree grows 15 to 30 feet tall with dark-green, deciduous leaves up to 6 inches long that turn orange or scarlet in the fall. Fragrant, white, cup-shaped flowers measure 3 inches across and bloom throughout the summer until the first frost. The flowers are followed by fruit in a woody capsule that stays on the tree until the following year. Plant Franklin tree in full sun or under taller trees and in a soil that is moist and well-drained. The tree is hardy in USDA Hardiness zones 6 to 9 in Oregon.
Honeylocust (Gleditsia triacanthos), also known as thornless honeylocust, is a member of the bean family. The tree grows 40 to 80 feet tall with a spread of 20 to 30 feet. The tree produces compound leaves that measure 7 to 8 inches long and are made up of at least 100 oval-shaped leaflets that are 1 inch long. Fragrant green-yellow flowers grow in small, hanging clusters in early summer and are followed by dark purple-brown seed pods that resemble a corkscrew. They grow 10 to 18 inches long and 1 inch wide. Plant honeylocust in full sun and a soil that is moist to wet. The tree is hardy in all of Oregon.