These compact shrubs can replace perennials:
Hydrangea
'Little Quick Fire,' 'Bobo,' 'Little Lime' (pictured)
Weigela
'Spilled Wine,' 'My Monet' (pictured)
Dogwood
'Arctic Sun'
Viburnum
'Lil' Ditty,' 'Bailey Compact' (pictured)
Lilac
'Tiny Dancer,' 'Bloomerang' (pictured) Clethra
'Vanilla Spice,' 'Ruby Spice' (pictured)