Zone 3

• In USDA zone 3, average annual lows drop to minus 40 degrees Fahrenheit. The Tatarian dogwood (Cornus alba) is hardy in zones 3 to 7 and grows to 10 feet tall with an equal spread. This fast-growing deciduous shrub has arching branches covered with dark leaves that turn red and purple in fall. It blooms with white flowers in summer and has blood-red stems that stand out in winter landscapes. Tatarian dogwoods prefer moist, well-drained soil and sun to partial shade. The winterberry (Ilex verticillata), a member of the holly family, is hardy in zones 3 to 9 and grows to 15 feet tall. This native deciduous shrub thrives in moist, slightly acidic soil and sun to partial shade. Winterberries produce white flowers followed by long-lasting red berries that attract birds.
  
  

Zone 4

• Low temperatures in USDA zone 4 dip to minus 30 degrees. The shadberry (Amelanchier arborea var. arborea) is hardy in zones 4 to 9 and grows from 15 to 25 feet tall. This deciduous shrub is native to the northeastern U.S. and blooms in early spring with white-pink flowers, followed by red-purple fruits. It grows well in a range of site conditions, from wet to dry soil and sun to partial shade. The common pearlbush (Exochorda racemosa) grows to 15 feet tall and is hardy in zones 4 to 8. A deciduous shrub, the pearlbush blooms in early spring with showy white flowers. This hardy plant tolerates drought, heat and severe pruning and thrives in well-drained, acidic soil in sunny to partially shaded exposures.
  
  

Zone 5

• Shrubs must tolerate average lows to minus 20 to thrive in courtyards in USDA zone 5. Scotch broom (Cytissus scoparius) is hardy in zones 5 to 8 and thrives in sunny sites with poor, dry or clay soils. This hardy deciduous shrub grows to 10 feet tall with a 6-foot spread and produces showy yellow flowers in spring. It tolerates drought and salt and has an upright, open form. Hardy in zones 5 to 7, the Chinese yew (Taxus chinensis) grows quickly to 15 feet tall with a similar spread. This evergreen has dense foliage, tolerates drought and thrives in sunny to partially shaded sites with moist, well-drained soil.
  
  

Zone 6

• Low in USDA zone 6 dip to minus 10 degrees. The tea-oil camellia (Camellia oleifera) is hardy in zones 6 to 9. This evergreen shrub grows to 15 feet tall with a 12-foot spread and has glossy, dark foliage. It blooms with aromatic white and yellow flowers in fall and winter and grows well in sun to partial shade and acidic, moist soil. Another evergreen, the Japanese cleyera (Cleyera japonica), grows to 12 feet tall with a 10-foot spread. Hardy in zones 6b to 8, this upright shrub has dark, lustrous leaves and produces white flowers followed by black fruits. It prefers sunny or lightly shaded sites with moist, well-draining soil.