Unseasonably warm weather means flowers have bloomed a month before Canberra's Floriade festival begins.

ANU climatologist Janette Lindesay says winter is getting shorter and spring is starting earlier, and commercial horticulturalists like Paul De Jong are having to adapt to the changing weather.

Floriade organisers are not planing to bring forward the opening and are confident the flowers will look vibrant throughout the month-long festival.