Wabi-cha was started in the mid-16th century and Sen-no-Rikyu perfected the philosophy of Wabi and Sabi at the end of the century.
Although Chabana doesn’t have very strict rules (not like other major schools of Ikebana), it still have some complex criteria to follow. There should be some intellectual and modest meaning behind all arrangement of the items in the small tea-room. The flowers should be seasonal and fresh from a garden or in a field. Fully bloomed flowers are NOT preferable, almost opened or half-opened flowers are ideal. NO flowers with sharp thorns nor flowers with strong scent are allowed in a small tea-room. These gentle thoughts must be considered for your important guests. (there are many books and records of old tea-masters with their careful preparation and heartfelt episodes.)
Flower vases and containers for the tea-room are not main vessels like other tea utensils. Chawan (tea-bowl), Mizusashi (fresh water jar) and Chashaku (bamboo tea scoop) are more important. Yet simply arranged flowers in a carefully chosen vessel would be a focal point of a quiet conversation in the tea-room.
Personally I dislike too much stylised tea-ceremonry by many kimono ladies these days. I would rather love to follow the manners of the tea-masters in the 16th century.
Anyone can enjoy tea-ceremony without understanding deep thoughts of Wabi and Sabi, but misunderstanding of tea culture may lead you somewhere completely irreverent. (Gas)