What Effect Do Coffee Concentrations Have on Bean Plant Growth?


Coffee is a very popular drink, but it also has other uses as well. There are various components in coffee that affect various aspects of plants and gardening. Coffee grounds contain a large amount of nitrogen, and the caffeine in coffee has different effects on the bean plant.

Low Concentration of Caffeine

In low concentrations, less than 1,000 micrometers, caffeine directly applied to the mung bean seed affected the rooting of the mung bean by causing a stunting affect. Roots grew, but they did not produce the normal range of growth.

Higher Concentration of Caffeine

When larger concentrations, more than 1,000 micrometers, of caffeine were applied to the mung bean seed, the roots were reduced further. When 2,000 micrometers of caffeine was added to soil, the roots did not grow all.

Antibacterial Effect

Caffeine is a chemical deemed safe for use in managing pests. Experiments with an extract made from coffee waste showed that when applied to the leaves of bean plants, the coffee material proved to be an antibacterial solution that killed a disease causing pathogen called Pseudomonas syringae.

Soil Benefits

When coffee grounds are added to the garden soil of bean plants, the nitrogen content in the coffee improves the growing medium and the beans thrive. The grounds can also be used as a mulch on top of the soil, which will allow the nitrogen to slowly dissipate into the soil over time.

Natural Pest Control

Coffee ground mulch laid around bean plant seedlings will act as a natural repellent to slugs and snails. You can also use a very strong brew of coffee and pour or spray it directly onto the soil to keep pests away.


  • Give Your Garden a Jolt With Coffee Grounds
  • Caffeine Affects Adventitious Rooting
  • Antibacterial Activity of Tea and Coffee Wastes
Keywords: coffee grounds, plant seedlings, mung bean, bean plant, caffeine in coffee

About this Author

Gemma Argent writes articles and essays for Associated Content, HART, Horizon Magazine, and Canada. She writes fiction for Aria Kalsan and sci-fi and essays for Writing Edge magazine. She has bachelor's degrees from the University of Nevada, Reno, in environmental resources and archaeology and has done graduate coursework from the University of Nevada, Las Vegas, in water resources and writing.