Annabelle Smooth Hydrangea

Annabelle is the hydrangea that made smooth hydrangeas popular, and it has stayed in gardens since the 1960s on the strength of one thing: enormous white flower heads, up to a foot across, on a shrub that blooms every single year. Hydrangea arborescens 'Annabelle' grows 3 to 5 feet tall and 4 to 6 feet wide in part shade, hardy from Zone 3 through Zone 8, and reaches full size by the third season.

Bloom starts in early summer and holds for weeks, opening pale green, turning pure white, then aging back to green by late summer. The dried heads stand into winter and hold their shape under snow.

Smooth hydrangea flowers on new wood, which is the whole reason for its reliability. The buds form in spring on the current year's growth rather than sitting on last year's stems through the winter, so a hard freeze or a late frost cannot take the display. It blooms in Zone 3 where the bigleaf types will not, and soil pH does not change the color.

Cutting back to about 18 inches in late winter rather than to the ground builds a sturdier framework to carry the flower heads. It wants consistent moisture, tolerates wet ground, and prefers shade from midday on in hot climates.