Originally Posted by momoese

This is from the page you linked to.

"Blue bamboos, White bamboos and Red bamboos all have moments in their lives when they are absolutely blue, red or maybe white. But these are moments. The spectacular color usually occurs when the plant is putting up its newest canes. Blue and White bamboos throw new shoots that are covered with a lot of powder (sometimes called ‘bloom’). When the canes are covered in this powder they appear (convincingly) to be blue. If you look at the photos on this site you will see examples of this color. None of the photos have been digitally altered but they were taken at particular moments in the life of the plants."