You have probably heard about the practice of watering houseplants with cold, leftover coffee. This popular beverage is supposedly beneficial not only for you but your plants as well.
So is old coffee water good for houseplants, or is it a myth?
Coffee’s Plant Nutrition
Coffee has a few specific properties that some people tout as beneficial for plants. These include calcium, magnesium, potassium, and nitrogen. While it is true that these ingredients can be useful for certain houseplants, there are both advantages and disadvantages to watering your plants with cold coffee.
Here are a few key advantages to adding some coffee to your plants’ soil:
Potassium and nitrogen
- Potassium and nitrogen are plant fertilizer plants, promoting healthy leaf and stem growth. Coffee can serve as an inexpensive and convenient alternative to commercial fertilizer brands.
- Magnesium is an essential nutrient for plants. Magnesium is an important compound that contributes to keeping leaves green and lush and boosting photosynthesis.
- Some plants thrive in acidic soil. Some species include Cyclamen, Aloe Vera plants, African violets, Jade plants, and Philodendrons.
- Coffee is an acidic substance, and not all plants thrive in such an environment. If your plants’ leaves begin to yellow after you water them with coffee, this indicates a surplus of acidity.
- Too much caffeine is not suitable for indoor plants. While brewed coffee contains less caffeine than pure coffee grounds, it is still best to limit the amount of coffee you give to your acidic plants.
As long as you use pure water most of the time, the occasional coffee addition should be okay. Your acid-loving houseplants can safely benefit from some leftover brewed coffee for their soil about once per week for extra nutrients.