What is the flower language and meaning of the gardenia?

The flower language of the gardenia is "eternal love and promise." A beautiful sentiment. The gist is that this flower begins forming buds in winter and does not bloom until near the summer solstice; the longer the budding period, the more lasting its fresh fragrance; the leaves of the gardenia tree also stay green and unfading through wind, frost, snow and rain all year round. Thus, although its blooming seems casual, it has gone through long effort and persistence. Perhaps the gardenia's growing habits fit this flower language even better. It is not only a token of love; beneath its plain, lasting, warm and refined appearance lies the essence of a beautiful, resilient and mellow life.
Legend says the gardenia is one of the seven fairies from heaven. She longed for the beauty of the mortal world, so she descended to earth and became a flowering tree. A young farmer, alone and living in poverty, saw this small tree by the edge of a field and transplanted it home, tending it with every care. The small tree then grew full of vitality and bore many pure white flowers. To repay her master's kindness, she washed his clothes and cooked for him by day, and by night her fragrance drifted beyond the courtyard. When the common people learned of this, from then on every household began to grow gardenias.
Because the gardenia is the incarnation of a fairy, every woman wore one, and truly flowers bloomed everywhere and fragrance filled the world. There was a pure young maiden of gentle and elegant bearing named Gardenia. She had a quirk: she loved everything white, from the clothes she wore to all the furniture in her home, all in white. She was a devout believer and often prayed to God, praying that in the future she could marry a husband as pure as herself.
One winter night, someone knocked at the door. She opened it and saw an angel dressed in white with white wings. The angel said to her: "I am a pure angel. I know there is a pure man in this world who can match you, so I hurried here to tell you." And from his bosom he took out a seed and said to her: "This is a flower seed that exists only in heaven. You need only plant it in a pot and water it every day; on the eighth day it will sprout, and its branches and leaves will gradually flourish. And most importantly, you must keep your body and mind pure every day, and kiss it once every day." Before the maiden could ask the flower's name, the angel had vanished into the night.
Gardenia carefully cultivated this seed as instructed, and at last saw it bloom into a pure white and elegant flower. Counting the days, a year had passed, and on that very night the angel appeared again. The girl joyfully told of that fragrant, beautiful flower and what she had learned from it. The angel said: "You truly are a holy maiden. You shall have the purest gentleman to pair with you." Having said this, the angel's wings fell away, and he became a handsome and elegant young man. At last they were united and lived a happy life. This pure, elegant and beautiful white flower is the gardenia.