My 3 year old B. sanguinea has grown to a great height, and seems healthy in its environs except for one thing: the blooms barely last a day before fading and dropping. Soon after opening nicely in full color I can see the corolla fade, and within 36 hours it has been shed, leaving behind an unsightly calyx with stigma sticking out. This has happened to every bloom since I have had the shrub. Everywhere I walk here in San Francisco I see various types of Brugmansia with long-lived blooms hanging for weeks.
Has anyone had this problem, or know a cure??