Plants need light to survive. During photosynthesis, they use light to make the sugars they need to grow. But did you know plants also use light to regulate their growth? Through a process called photomorphogenesis, they sense the light’s colour, brightness, direction, and duration. This helps them move through their life cycle in ways that boost their chances of survival and reproduction.

Different colours (or wavelengths) of light impact plant growth in unique ways. Take a look at these flowering plants that were grown under different lights:

Image shows three columns. The first column features flowers with a red light overhead. The middle column features flowers with a blue light overhead. The third column features a mix of blue and red light overhead.

RED LIGHT

BLUE LIGHT

MIX OF RED AND BLUE

THINK-PAIR-SHARE

Assume optimal growth and development happen under red and blue light. With that in mind, think about these questions:

  1. What differences do you notice between the plants grown under different lights? Be specific.
  2. What qualities of the plants grown under red or blue light alone seem suboptimal?
  3. Can you develop a hypothesis for these differences based on what you know about light and plant development?