Experiment: The Effects Of Colored Light On Plant Growth (Clear VS Green VS Blue VS Red VS Black)
I did an experiment in school years ago relating to the effects of plant growth under different colors of sunlight which may assist some people when growing small amounts of personal food in the future. In the experiment I used various different colored translucent paint which was applied to the outside of a series of clear plastic containers making each one a different color (clear, green, blue, red, black), which were then placed over the growing plants. Natural sunlight was used as the primary light source for each.
My findings were as follows...
The Effects Of Colored Light On Plant Growth
Clear = This is the benchmark to base the others off of.
Green = Started out much faster then the others, but ended up weakening over time. My finding was it helps rapidly increase the initial germination process but hindered the mid/late stages of growth such as producing leaves or flowers.
Blue = No real impact on germination early on but had a drastic affect in the mid/late stages of growth especially in the production of bigger, stronger and faster leave growth. The downside of blue light appeared to be the reduction of the flowering aspect of growth in the plants.
Red = No real impact on germination early on but had a drastic affect in the late stages of growth especially in the flowing phase, producing bigger, strong and faster flower growth. The downside of red light appeared to be the reduction of the leaf growth aspect in the plants.
Black = Late germination with a weaker starting plant, with very little growth in the short term, which had major issues developing leaves or even holding its own weight. Died early (even with added support) in the leafing stages and well before any flowing occurred.
The general take-away when everything was said and done was...
- Start with green light to greatly speed up germination and early plant development (stop once stem is about 1-2 inch out of the soil)
- Switch to non-colored light for a short period after that to slightly strengthen the stem development (stop shortly before leaf phase starts)
- Switch to blue light after that to greatly increase leaf development (stop when the leaves start getting to large for the stem to support)
- Introduce a short period of non-colored light to again help strengthen the stem to better handle the new weight (stop once drooping is minimized or when budding starts)
- Lastly switch to red light shortly after budding takes place to greatly increase flower/seed development (stop once flowers are mostly fully developed), and lastly shortly after fully flowering switch back to non-colored light for the remaining plants life cycle.
This same logic can also apply to many edible plants, although the timing/effects of the different colors of light can range depending on what type of plant is grown, but in general the above framework can be used with many different types of plant growth to greatly optimize the total growth time, overall yields as well as increasing the expected life cycle length of the plants involved.
great post
Isn't color somewhat irrelevant? Photosynthesis only needs UV light, maybe that some colors block more of it than others? Anyway thanks for the read.
Hi @gregan, I was going to reply directly here but my answer grew too large. The shortest answer is that blue and red light are most important to photosynthesis, but the plant senses light colors independently of photosynthesis and uses them as developmental cues. If you want to learn more you can see my full post.