Zone 3

• To thrive in U.S. Department of Agriculture plant hardiness zone 3, small-rooted trees must tolerate average annual low temperatures to minus 40 degrees Fahrenheit. The amur maple (Acer ginnala) is hardy in zones 3 to 8. This deciduous tree grows slowly to 20 feet tall with a 28-foot spread. It has a rounded crown and small, trilobed leaves that turn bright red in fall. Amur maples prefer sun to light shade and tolerate a range of soils. The Saratoga ginkgo (Ginkgo biloba "Saratoga") grows to 40 feet tall with a 30-foot spread. It's hardy in zones 3 to 9 and prefers full sun. It tolerates drought, heat, pollution and a range of soil types, and has an upright, rounded shape.
  
  

Zone 4

• Average low temperatures reach minus 30 degrees in zone 4. The downy serviceberry (Amelanchier arborea) is hardy in zones 4 to 9 and grows to 25 feet high with a 15-foot spread. This deciduous tree has a narrow crown, and its foliage turns yellow and orange in autumn. Downy serviceberries prefer sites with sun to partial shade and moist soil. The Eastern redbud (Cercis canadensis) is also hardy in zones 4 to 9. It grows to 30 feet tall and spreads to 35 feet. Eastern redbuds have large, heart-shaped foliage and produce clusters of pink flowers in early spring. They prefer moist, well-draining soil, and sun to partial shade.
  
  

Zone 5

• In USDA zone 5, average lows reach minus 20 degrees. The kousa dogwood (Cornus kousa) is hardy in zones 5 to 8. It grows to 30 feet tall and spreads to 20 feet. This dogwood produces bracts of white flowers in spring and has dark-green foliage that turns red and purple in fall. It prefers sun to partial shade and well-drained soil. The goldenrain tree (Koelreuteria paniculata) grows to 40 feet tall with a 35-foot spread. It's hardy in zones 5 to 9 and grows well in full sun and a range of soils. This deciduous tree is named for its long panicles of yellow summer flowers.
  
  

Zone 6

• USDA zone 6 experiences average lows to minus 10 degrees. The Foster holly (Ilex x attenuata "Fosteri") is hardy in zones 6 to 9. This evergreen grows to 30 feet tall with a 10-foot spread and has spiny, glossy foliage. Foster holly trees produce an abundance of long-lasting red berries, prefer sun to partial shade, and tolerate a range of soils. The Japanese crape myrtle (Lagerstroemia fauriei) grows to 30 feet tall with a 15-foot spread. Japanese crape myrtles bloom with a profusion of small white blossoms and have attractive red-brown bark. They grow well in sun and moist, well-draining soil, and are hardy in zones 6 to 9.