Does blue and red light help tropical plats photosynthesize?

Question

does blue and red lights help tropical plants like euphorbias photosynthesize? if not what other colors?

Answer 1

Design and carry out an experiment!  It would be a lot more work than looking up the information online, but you'll probably enjoy the sense of accomplishment at discovering the answer for yourself.  

Find some tropical plants you can grow indoors in your home under controlled conditions.  Separate them and expose them each to only one kind of light: sunlight, yellow or "normal" room lighting, blue light, and red light.  Make sure all other conditions are controlled to be as equal as possible.  Monitor their growth, and see what happens!

You can learn more about the scientific method by searching online.

Answer 2

Red is a complimentary colour to green, so plants absorb more in the red light wavelength. I think in general the majority of plants would grow best in red light, and worst in green light.