Backlight is one of may favorite types of light to work with flowers and it is one of the easiest to use. Most flowers are somewhat translucent, and just moving to the opposite side of the flower from the source of the light changes the scene dramatically. The petals and sometimes the leaves, filter the light coming through them, creating this effect that I compare with stained glass light. Backlighting your subject this way is great for bringing out and saturating the colors. I also believe the back light brings out a depth and dimension that will add extra life to your flower photography. Another bonus is the out of focus highlights can help with framing your focal flower. This can be done at all times of the day but will be easier and work best in the earlier and later hours of the day. Near high noon, you will have to get very low to back light the blossoms. Give this a try the next time you are out. The exposure is usually easy, check your histogram and make any adjustments needed at the time.