The effort of producing rainbow roses was initiated in 2004 by two dutch companies, River Flowers and F.J. Zandbergen. They experimented and successfully grew a rose that had its petals rainbow colored. This is how it was done: The dyes are produced from natural plant extracts and are absorbed by the flowers as they grow. As petals get their nourishment through stem, the idea is to split the stem into several channels and dip each one in different colored water. This way all the colors will be drawn by the stem into petals and resultant rose will have all the colors in it. A set of 12 roses costs about £50.