Introduction
Using grounded coffee in many peoples garden lawns is actually a somewhat common practice in order to make plants grow faster. “Caffeine, a chemical stimulant, increases the biological processes in not only humans but in plants as well” (Grant 2016). Caffeine can be added to the soil by sprinkling ground coffee over the top of the soil, addition of non-consumed coffee to the pot as a substitution for water, or watering the plant with a solution of water and a dissolved caffeine tablet. It is predicted that the coffee grounds and water mixture will contribute to the initial plant growth happening more rapidly rather than that of a plant grown with just water.
Materials and Methods
Materials consisted of a pack of bean seeds, 3 different pots, soil, tap water, coffee grounds, caffeine tablets, a beaker, and a ruler which can be measured in mm. In order to get a constant result I had prepped the bean seeds by allowing them to originally germinate for the first 5 days off of just tap water, after the fifth day was when I changed up the experiment and that’s when I added the coffee, the mixture of caffeine and water, and then the control experiment (tap water) to each plant. Every day I would measure each of the plants and then divide by 10 to get an average height for the bean plants. For the caffeine solution I would dissolve 10 grams of caffeine tablets into 100ml of tap water in a cup. Mimicking the caffeine tablets I would also add 10 grams of coffee grounds to 100ml of tap water in another cup. I would test the water, and the two solutions of caffeine on the 3 separate pots of germinated beans, by watering the separate plants once a day. I would them measure in mm the height of each pots with the bean plants inside and calculate the average height of the plants.
Results
Coffee grounds added to water provided the best mixture for the first 10 days of growth for the bean plant at 125mm. Caffeine powder mixture provided the least amount of growth at 71mm. All averages were rounded to the whole number. Table 1 shows the daily measurements of the average height of the ten bean plants within the three separate pots, and Figure 1 shows these daily averages of the plant height graphically.
Table 1. Average height of plants (mm) for three bean plants.
Solution Height of bean plants in mm
Day
1 2 3 4 5 6 7 8 9 10
Water 38 46 53 61 68 77 85 92 99 107
Caffeine 37 43 48 52 56 59 62 65 68 71
Coffee 39 47 55 63 72 81 92 102 113 125
Figure 1. Average height (mm) for three separate bean plants.
Discussions and Conclusion
The original hypothesis that the beans watered using the coffee ground and water mixture would initially grow the fastest was proven to be true. Gardeners should look at possibly using coffee grounds in addition to watering their plants in order to speed up the initial process of plants, which was proven to be slightly better than that of just water. However, the difference isn’t to great so it wouldn’t cause a great difference in speed of plant growth. After doing some brief research on the topic of caffeine on plants it might actually be better to stick with just water. For example, “Studies involving the use of caffeine on plants have shown that, initially, cell growth rates are stable but soon the caffeine begins to kill or distort these cells, resulting in a dead or stunted plant.” (Grant 2016). This quote from an article published on the website Gardening Know How would have been helpful for me to have seen while I was doing my experiment so I could have tested for more days in order to see if it is true that caffeine initially speeds growth in plants, but later would result in distorting and possibly killing the plant. Possibly some future research should test a longer period of time where the plant would begin to show signs of the caffeine shunting the growth so that if gardeners who want to use coffee, or caffeine on their plants they will know when the caffeine will lose its benefits for the initial plant growth.
References
Grant, Amy. “Caffeine Use In Gardens: Caffeine Insect Repellent And Fertilizer.” Gardening Know How, 25 May 2016, www.gardeningknowhow.com/garden-how-to/soil-fertilizers/will-caffeine-affect-plant-growth.htm.