In mid-August, the “Star Osmanthus” tree at Children’s Park produced the city’s very first osmanthus blossom of the year, leaving many locals wondering “when will the flowers burst into full bloom?” According to Hangzhou Botanical Garden, the season’s first is about to enter its blooming window—possibly as early as this week.

As the bellwether for osmanthus flowering in Hangzhou, the early silver osmanthus buds at the Botanical Garden are swelling rapidly, ready to pop. Early silver osmanthus is one of the earliest osmanthus varieties to bloom in autumn in Hangzhou, opening in shades of yellow-white to creamy yellow with a rich fragrance. Right now, plump, pearl-like buds are visibly bulging as tiny flowers inside push against their casing. On clustered inflorescences, these little buds are poking their heads out one after another, packed together like green-white jade stones, waiting to unfurl. The buds have now entered the “shell-topping” stage and will pass through the “bell-stem” and “fragrant-eye” phases before finally reaching full bloom.　　

The Botanical Garden explain that osmanthus is quite climate sensitive—its blooming depends on cracking a unique “weather code.” The key trigger for bud break is a sustained average temperature of 20°C to 22°C. Once that condition is met, flowers will appear within four to seven days.

Looking at the near-term forecast, minimum temperatures will stay above 20°C for the rest of this week, then drop back to 20°C next week. Taking all meteorological factors into account, this year's first wave of osmanthus should begin opening as early as this week, or next week at the latest.

Once the tiny buds of the early silver osmanthus unfurl one by one, the “citywide fragrance” that Hangzhou residents hold so dear will arrive right on cue.