Caffeine Effects on Plant Growth

As caffeine is a natural, plant-derived substance, it's a common scientific curiosity to find out if other plants are as receptive to the stimulating effects of the substance as humans. Will a plant respond to a caffeine-spiked unit of water with the same energetic spike that we get from a cup of coffee?

In its extracted form, caffeine is bitter to the taste, with a white, crystalline xanthine alkaloid structure. Pure, extracted caffeine is usually distributed in powder form, though 90 percent of Americans consume it daily in coffee or caffeine-enhanced soft drinks. Caffeine is a psychoactive stimulant drug (statistically, the most commonly consumed psychoactive substance in the world), but it's not an agricultural practice to add it to plants.

Caffeine comes from plants, where it was developed over time to be part of the plant's natural defense system, providing an insecticidal, antimicrobial barrier. Caffeine is produced, in varying levels of concentration, in all parts of the plants that make it. When fed upon, caffeine paralyzes and kills some of the insects that feed on the plant, as well as causing sometimes-severe intestinal discomfort to grazing herbivores. Caffeine does not seem to transfer to other plants in the landscape (luckily for them, as studies seem to indicate).

In 1982, a team of scientists published a study in the European Journal of Cell Biology. The study suggested that introducing caffeine to growing plants inhibits cytokinesis (the final stage of cellular mitosis) in the plant cells. Since caffeine has a negative effect on this vital stage in cellular growth, the study suggests that putting caffeine on plants will cause a considerable detriment to growth.

A team at the University of Michigan chose to study the effects of caffeine on plants by feeding groups of 16 Wisconsin Fast Plants varying concentrations of caffeinated water. Their study showed that high caffeine concentrations killed sample plants by physically and chemically changing them, massively reducing their capacity for growth.

Are you thinking about running an experiment that introduces caffeine to plants in order to watch how it affects growth? First, consider the additives in the caffeinated substance you're thinking of using. Many will considerably affect the pH level of the soil, as most caffeinated drinks are highly acidic (and will force the plant to divert growth energy to protect itself). Choosing to run the experiment with a solution of powdered caffeine in water will reduce the variables inherent in changing soil pH.