The plant known as the corpse flower is expected to bloom some time Friday.
The event, which only happens about once every 10 years, results in a putrid smell often compared to rotting flesh.
The flower is known scientifically as Amorphophallus titanum and more casually by gardens staff as "Rosie."
Despite the smell - or perhaps because of it - Rosie is quite popular, with hundreds visiting the flower even before it blooms. The bloom is expected to last about 24 to 36 hours.
In Southern California, the Huntington Library and botanical gardens has a corpse flower, where it last bloomed in 2014.