The Effect of Capsaicin on the Growth of Sunflowers

Researched by Stockton B.


The purpose of this experiment was to determine the effect of pepper extract on the growth of sunflowers. Pepper spray is often used to prevent insect damage so it is important to know if it can damage plants like a sunflower.

I became interested in this idea because I have always liked sunflower seeds, and wanted to find a better way of growing them.  

The information gained from this experiment may help the farming of various plants, especially sunflowers. If pepper spray is harmful to plants then it should be used very cautiously to control insects.
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My hypothesis was that the greater amount of capsaicin (pepper extract), the less growth of the sunflower.

I based my hypothesis on the fact that this particular chemical in peppers is fairly harmful, and if used on a plant it would most likely damage it, according to Wilbur Scoville, the man who invented the first way of measuring heat of chili peppers.
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  •  The constants in this study were: 
  •  The soil type; 
  •  The amount of soil;
  •  The amount of time for growing (two weeks);
  •  Size of pot; 
  •  Type of sunflower; 
  •  Ph level of water;
  •  Amount of sunlight; 
  •  Amount of seeds in pot (4 seeds); 
  •  Amount of water given.

The manipulated variable was amount of capsaicin applied to each plant.

The responding variables were the height and mass of the plant after one month.

To measure the responding variable first measure the height with a millimeter ruler, then use a triple beam balance to measure the mass of the plants after they have been plucked and cleaned of dirt.
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Quantity Item Description
Round flowerpots (Same size and shape)
12  Sunflower seeds (same species)
1 Small, round dish
4 Tissues
1 Container of diluted capsaicin
1 Triple beam balance scale
1 Millimeter ruler
1 100 ml graduated cylinder
1 Long plant lamp
Aluminum trays
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1. Place a large amount of tissue on a small tray.
2. Set 12 healthy, un-cracked sunflower seeds on the tissue.
3. Place a bit more tissue on top of the seeds.
4. Keep in safe, warm place.
5. Water twice a day until seeds are germinated. (Each seed has a white root growing out of them, poking out about 1 centimeter. )
6. Label each of 3 pots with amount of capsaicin.
7. Put 650 ml of potting soil in each flowerpot.
8. Poke hole about 4. 5 centimeters deep in each pot’s soil.
9. Place 4 sunflower seeds in each of 3 flowerpots.
10. Gently cover hole entirely without pushing or packing down soil.
11. Set two pots in one tray and the third in the second tray.
12. Set lamp about 1 foot above the flowerpots.
13. Water regularly with 200 ml a day until they are about 18 cm tall.
14. Write in journal.
15. Take a picture of fully-grown sunflower.
16. Add 116 ml of capsaicin to 116 ml of water.
17. Mix well until capsaicin is spread completely through the water.
18. Repeat step with 232 ml of water.
19. Repeat step 17.
20. Write in journal.
21. Water each sunflower equally until the bottle is empty.
22. Leave for 1 full day and return.
23. Inspect plant carefully until positive of either the plant changing, or staying the same.
24. Take a picture of the sunflower.
25. Label both pictures; name early one “before” and the later one “after”.
26. Pluck, wash, and dry each flower, keeping them in their correct groups.
27. Measure and weigh each plant with triple-beam balance.
28. Write experiment results in journal.
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The original purpose of this experiment was to determine whether capsaicin (pepper extract) would affect sunflowers.

The results of the experiment were that capsaicin would make a fair pesticide; the sunflowers’ growth was completely random. The plant with 0 ml of dilution grew to 27 inches and weighed 63 grams, and the one with 232 ml of dilution grew smaller.

See my table and graphs.

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My hypothesis was that the more capsaicin added the worse the plant’s health would be.  

The results indicate that the hypothesis should be rejected because the sunflowers growth was not stunted. There was no change in the plants at all.

Because of the results of this experiment, I wonder if growing peppers and sunflowers in the same pot would control insects without damaging the sunflowers. I wonder if other plant species would also be harmed.  

If I were to conduct this project again, I would have done many things differently. First of all, I would use much more exact measurements. I would also grow them when it is warmer, to be able to grow them outside, in the sunlight and real soil. I would have liked to have more plants per group as well, and dilute the pepper spray more.
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 Sunflowers are used for many different things that are important to society. One of its more important productions is its use in gasoline, engine oil, and vegetable oil. To help grow this crop, farmers have resorted to pesticides, which contain different chemicals that sometimes harm the very plant it was supposed to protect. Capsaicin, extracted from peppers, is sometimes used as a pesticide and is still being tested.  

Helianthus (Sunflowers)
The Helianthus is grown in most parts of the world and is very important to mankind. Many different pesticides are used to protect them, but some actually kill the very sunflower it is protecting. There are 60 types of helianthus; each is a carefully grown and preserved crop. The most common type is about 3-10 feet tall when fully grown, and has a head over 1 foot across. Every head has a disc of tiny tube flowers between a fringe of yellow petals. One sunflower can hold up to 1,000 seeds. Sunflower seeds are rich with protein and oil, which play a part in things like margarine, cooking oil, and diesel fuel. Many kinds are used for food, also. Sunflower seeds are popular snacks. Birds and rodents are also fed sunflower seeds, mixed with other things.

Capsaicin can be extracted from any kind of pepper and is used in pepper spray, hot sauce, and many other things. Capsaicin is the chemical in peppers that gives a burning sensation; so the hotter the pepper the more capsaicin is in it. It is generally found in the ribs and seed area of the pepper. It serves as important to America though many don’t know what capsaicin even is. It is used in liquid heat for massaging when is diluted, so who knows what it could do without any dilution. It is also used in hot sauce, though extremely diluted. The police and many others use it for self-defense, as it is also used in pepper spray.

 The scientific name for peppers is capsicum. There are five different types of peppers, capsicum annum, capsicum baccatum, capsicum chinense, capsicum frutescens, and capsicum pubescens. Each species of capsicum varies in heat and size, as well as where they are grown. Capsaicin can be extracted from each of these but the most powerful capsaicin is extracted from habanera peppers.  

Scoville Unit
The first way of measuring pepper heat was invented by Wilbur Scoville. One scoville unit is 100 drops of sweetened water into hot sauce. He added water until the sauce no longer burned his mouth; the amount of scoville units it took to keep the sauce from burning was the heat of the sauce. Pure capsaicin is 16 million scoville units. It is used in liquid heat for massaging, but that’s when it’s diluted.  

Essentials for Life
Photosynthesis is literally essential to any and all life. It is a process that is powered by sunlight in plant cells that contain chlorophyll. The plant then releases oxygen, finishing a cycle. The actual chemical process is 6 H20 + 6 CO2 => C6 H2O6 + 6 O2. Oxygen allows animals, including humans, to breathe.

Human Needs
 Sunflowers are important to mankind and are carefully grown. Peppers perhaps are less important but still very widely used when it comes to food. They are chopped, blended, cooked, de- seeded, or juiced for various salsas, sauces and other things. Sunflowers and peppers are almost never used together, but it was a brilliant idea for one to help the other. But the question is if it will work. If so, more peppers will be bought, and sunflowers will survive the growing season more often.

Sunflowers contribute to the many different oils that get us from one place to another like gasoline and diesel fuel. It is used in vegetable oil that many Americans use in cooking. Its seeds are used to feed all kinds of animals from rodents, to birds, and even people. On the other hand, though a bit less important, peppers and capsaicin are almost as widely used. Peppers are chopped, cut, juiced, de-seeded, and blended to serve as food, protection, and now, farming. Peppers are mostly blended and mixed with various other chemicals to make food spicy, or chopped to go in stir-fries or other foods. Capsaicin is even used in medicine by some doctors to be put in prescriptions. Another important use is pepper spray to disable animals and criminals, used mainly for self-defense. Many farmers are also using capsaicin in farming as a pesticide, though most aren’t positive that it will protect and not kill the plants.


Challoner, Jack. “The Visual Dictionary of Plants” New York, NY Darling Kindersley inc. 1992

 “Helianthus” Helianthus Sunflower 11/19/03 http://www. botany. com/helianthus.html 

Coffman, John M. “Sunflower” World Book Encyclopedia 1999

Price, Hugh C. “Pepper” World Book Encyclopedia 2002

 “Extract” Chili Pepper 12/7/03 http://www. chili-pepper. com/extract.html 

“ Measuring heat/ growing and using chili peppers” http://chili-pepper-plants. com/indexphp3 

 Alt, Gary. “Capsaicin” Microsoft Encarta Deluxe 2001

 “Sunflower planting” http://www. Sunflowers. com/planting.html 

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I would like to thank the following people for helping make my project possible:

  •  My parents for helping me grow and help take care of the plants.
  •  Mr. Newkirk for giving me supplies and for helping me just about every step of the way.
  •  Mrs. Helms, also for helping me and give me what I needed when I needed it.
  •  Mrs. Hostetler for helping teach me about science.


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