The name of the flower is pronounced as DAY-lee-ə in British English.
― Anonymous User 6/23/2018
2
This beautiful name can also be pronounced /ˈdälyə/ (i.e. "doll-ya") as per the Oxford US dictionary. This is the pronunciation I usually hear in Northeastern United States, and I think it makes the most sense given the etymology of the word: Anders Dahl's last name is pronounced /däl/ (i.e. "doll"), after all!