The phrase "whose flowers" is correct and can be used in written English.
For example, you could use it in a sentence such as: "She was admiring the garden whose flowers were in full bloom."
They tried lantana, a perennial whose flowers smell, rather limply, of banana and passion fruit.
Beauties are but weeds in a garden whose flowers are stylists.
They rely on the tree, whose flowers attract bees, as depots for gathering honey.
On the banks of these pools are sandalwood trees, whose flowers and leaves hang down and diffuse perfumes everywhere.
On the drier areas were small groups of mountain pansies whose flowers varied from red to intense violet.
(Broken Arrow holds an open house in early June for the mountain laurels, whose flowers range in color from white and pale pink to red and burgundy).
"It used to be so strict," said Lotfi Lahmar, whose flower stall once sat across from the theater.
"I'm a girlie girl," said Jacqueline Kelly, whose flowered dress was bought for her, she said, by her mother, a tiny blond bombshell.
Arnica (Arnica montana L). is a perennial mountain plant whose flower heads are mainly used for topical treatment of bruises and sprains in phytopharmaceutical preparations such as ointments, creams and gels.
Ms. Menden, whose flower shop sits on a corner opposite the King Fahd Academy, said she was traumatized by watching what had begun as a peaceful protest deteriorate into a street riot beneath her window.
According to Councilwoman Jeanette Ard, whose flower shop and apartment were destroyed by the fire, "There was a time you could have fired a cannon down Front Street and not have hit a car or a person".
