Plant can see light.

Plant can differentiate between blue and red.

For flowering, the length of dark is important.

For plants, the length of day is equivalent to the period of lighting.

There are long day plants, and short day plants.

Only one specific colour (red or blue) inhibit or fostering flowering.

Far red light : 730nm. sunset's light, we can barely see it.

Plant remember what it has seen at last.

Phytochrome is a light activated switch.

Morning, Evening, More far red light because of the long distance

Phytochrome red get red light, then it becomes Phytochrome far red.

Blue blind plants or not