Once temperatures start to warm in early August, the buds of these temperate rainforest giants begin to swell.
By mid-September, you can admire their pineapple-sized flower trusses in several areas around Dunedin Botanic Garden's Rhododendron Dell.
Each truss carries from 20 to 30 florets and, depending on the species, can be coloured cream, yellow or pink, often with a splash of red or maroon in the throat.
This year's show is led by species such as R. magnificum, R. protistum, R. grande and R. macabeanum.
The latter two can continue to flower into mid-October.
Last year, they were followed by R. falconeri, which can continue into early November.
This year, R. falconeri is having a year off, so rather than enjoying its blooms we can anticipate the appearance of its felted new growth.
Along with the species, some of the large-leaved rhododendrons in the dell are hybrids, and flowering right now is a New Zealand hybrid raised at Pukeiti Garden, near New Plymouth.
Rhododendron ''Ina Hair'' is a R. macabeanum hybrid whose compact trusses open dusky pink in the bud and fade to cream with dusky pink spots in the throat of each floret.
This year, it is flowering for the first time in nine years.
The south bridge in the Rhododendron Dell provides an ideal vantage point for viewing its blooms.
• Doug Thomson is curator of the Rhododendron Dell at Dunedin Botanic Garden.
