My hypothesis is that the plants grown under red light will grow the tallest. This is because plants use red wavelengths during photosynthesis, which should give them more energy to grow - since red wavelengths are the longest. I also think the plants grown under green light will grow the least, since plants reflect green light instead of absorbing it, meaning they get less energy from it.

Below, I had put all the research (I've done into bullet points to easily understand it.)

• Red light helps plants grow taller and supports stem development (it is one of the main wavelengths used in photosynthesis.)
• Blue light helps plants grow strong leaves and increases the amount of chlorophyll is produced.
• Green light is mostly reflected by plants, which is why leaves look green. This is the reason why green light is less effective for a plant's growth.
• Plants under yellow and blue light can have stronger stems, likely because blue light supports leaf and stem development, and yellow light provides extra energy for overall growth.
• the secondary wavelengths made the plants grow faster since the plants got double the number of wavelengths.
• Clear (full‑spectrum) light contains all wavelengths, similar to sunlight, which can help plants grow faster and healthier.

This research helped me understand how wavelengths affect photosynthesis and why different colors of light produce different growth results.

Independent Variable:

• Color of light (red, blue, white, yellow, orange, pink, and purple)

Dependent Variable:

• Plant growth

Controlled Variables:

• Type of plant
• Amount of water
• Soil type
• Pot size
• Time exposed to light each day

Fill each pot with the same amount of soil. I did about 75%. Then...

1. Plant 1–2 seeds in each pot at the same depth.
2. Label each pot with the color of light it will receive.
3. Cover each pot with a different colored filter (yellow, blue, red, orange, pink, purple, clear).
4. Place all pots in the same location so temperature stays the same (under the growth lights)
5. Turn on the lights for the same amount of time each day (mostly 8-9 hours per day)
6. water the plants every other day for the first week, then water them every week for the rest of the experiment.
7. Measure plant height every 2 days for 10–12 days.
8. Record all measurements in a data table.

These are the observations I had made over the 2 weeks Day 1:

• I planted the lentil seeds and watered enough to moisten the soil.
• Total amount light received: 8 hours 30 minutes.

Day 2:

• I didn't water seeds today, since the soil was still moist.
• Total amount light received: 8 hours 30 minutes.

Day 3:

• The seeds under yellow, orange, and purple lights show tiny root sprouts. They are likely to fully sprout within the next 1–2 days.
• I also watered the seeds today.
• Total amount of light received: 8 hours 35 minutes.

Day 4:

• The seeds under clear light began to grow a small root.
• The blue seed had grown about 2 cm without me noticing.
• There was no visible growth for seed under red light or from the pink light one.
• Total amount of light received: 8 hours and 34 minutes Day 5
• WASN'T ABLE TO RECORD DATA Day 6
• The seeds under yellow, orange, purple, and clear lights have sprouted.
• I watered the seeds again.
• The seeds under the yellow, orange, purple, white and blue light all grew between 1 inch and 5 cm
• The total amount of light they got was 8 hours and 40 minutes

Day 7

• The seeds all grew about 3 cm Ish except for the pink and the red, which haven't even sprout yet
• I watered them today
• The total amount of light the plant received was 8 hour and 45 minutes

Day 8:

• Plant grew
• Placed seeds outside for 15 minutes for fresh air.
• Watered seeds.
• Total light received: 9 hours

Day 9 and 10

• There was a growth for the yellow light- about 3cm for the yellow light plant.
• The red-light seed finally sprouted.
• Nothing happened to the pink light.
• I watered the plants.
• The total amount of light received was 8 hours and 25 minutes Days 11 to 14
• The plants all grew.
• Some even grew their leaves
• The total amount of light received was 8 hours and 30 minutes
• I watered the plants

General Observations:

• Seeds under secondary wavelengths (yellow, orange, purple) grew the tallest, likely because these colors contain multiple beneficial wavelengths.
• Seed under red light grew slower and remained shorter than most other plants.
• Growth under blue light was medium—not as fast as orange, but faster than red and purple.
• Leaves looked healthiest under clear and yellow light, and slightly weaker under red light.
• Plants under yellow and blue light had stronger stems, likely because blue light supports leaf and stem development, and yellow light provides extra energy for overall growth.

FINAL GROWTHS FOR PLANTS

• CLEAR - 3 INCHES
• PURPLE- 1.5 INCHES
• ORANGE- 2.4 INCHES
• BLUE- 2.4 INCHES
• YELLOW- 2.8 INCHES
• RED- INCHES
• PINK - NO GROWTH AT ALL

The plants did not grow the way my hypothesis thought. I expected the red light to make the plants grow taller, but that did not happen. Instead, the following happened:

• The plants under yellow, clear, and orange light grew the fastest and tallest.
• Plants under red light grew slower and were a step back from the other plants.
• Plants under blue light grew at a medium rate (faster than red but slower than yellow since it's a mix of both wavelengths).
• Plants under red and green‑range wavelengths grew the least.
• Purple plant surprisingly grew faster than I expected them to.

This means that the plants may need more than just red light to grow strong and healthy. Like a human, it needs all the ''food groups (wavelengths) to stay healthy and stable.

The hypothesis I had written above, predicted that the plants under red light would grow the tallest, however, the results did not support my hypothesis. In fact, it was the opposite (nearly). The plants under yellow, clear, and orange wavelengths grew faster and taller than the plant under red light. This happened because orange and yellow wavelengths are a combination of 2 colors. This means that plants may need more than just red light to grow strong and healthy. Like a human, it needs all the ''food groups" (wavelengths) to stay healthy and stable.

This experiment helped identify that different light wavelengths affect how plants grow. Gardeners, farmers, or people who grow plants indoors can use this information to choose the right light for faster or healthier plant growth. For example, using yellow, orange, or full-spectrum lights/ wavelengths, could help plants grow better in areas sunlight is limited. Understanding how light affects plants can also help in designing greenhouses or indoor farming systems more efficiently since these are a key factor in the future of farming.

The sources of error for me would have been the fact that my red color filter was a bit too dark. It was still red, but the filter was a tad bit thicker, making the plant a step behind from all the other seeds. For example, when the plants started to grow, the red light's plant's seed had just sprouted. Another error of mine was that I wasn't able to submit the files and pictures of my project due to

Citations (links used):

• Types of Grow Lights for Indoor Gardening | Live to Plant
• How Does Light Color Affect Plant Growth? (With Examples)
• Photosynthesis
• Color - Visible Spectrum, Wavelengths, Hues | Britannica
• How is photosynthesis used in everyday life?
• photosynthesis in plants
• photosynthesis causing energy in plants
• Photosynthesis | Definition, Formula, Process, Diagram, Reactants, Products, & Facts | Britannica
• components photosynthesis
• Understanding Photosynthetic Output Under Different Light Colors | Live to Plant
• Does light color affect plant growth? – The Institute for Environmental Research and Education
• How Does Colored Light Affect Plant Growth? - Biology Insights
• Color - Visible Spectrum, Wavelengths, Hues | Britannica

I would personally like to acknowledge the following people for being there for me when I stressed about the plants not growing or the entire experiment failing or even when I needed someone to talk to while pulling off those research sessions that lasted until 1:30 am. First, I want to thank my old teacher, Mr. Le for suggesting that I join this club. Without his suggestion, I wouldn't have been doing this right now Secondly, I wanted to thank my family for helping me with the experiment, even if it was bringing the plants upstairs or helping me set up the plant station in my own bedroom. Last but not least, I want to thank my instructor, Ms. Dhillon, for being with me when I had any questions or when I just needed help staying wake. Ms. Dhillon was the reason I stayed up until 12 am finishing the data tables.