bract

Kobayashi said the vibrant petals are actually modified leaves known as bracts that require long winter nights — at least 12 to 15 hours of darkness a day — for their colors to change.

These colorful parts of the plant, often referred to as flowers, are actually modified leaves called bracts.

Just as most plants are fading at the end of the growing season, hydrangea flowers, technically long-lasting bracts, are at their best, maturing to deep blue, purple and a flight of wines.

Each flower is held in a cuff of threadlike bracts — the “mist” — and appears in spring and early summer.

Arching stems produce delicate white flowers and dusky pink bracts throughout the growing season, and the entire plant takes on burnished hues with cool weather in fall.