The natural tannic acid inside tea leaves leaches into the soil with rainwater as tea grounds decompose, thereby lowering the soil's pH and increasing acidity. This poses a problem for plants that require neutral to alkaline soils but creates the ideal conditions for acid-loving plants to thrive.

Can tea change the pH of soil?

There are four ways that tea is supposedly beneficial: curing “sickly” plants, lowering the pH of the soil, adding nutrients, and adding humus.

Are tea leaves good for the soil?

The evidence Dried tea leaves contain about 4.4% nitrogen, 0.24% phosphorus and 0.25% potassium. There is significantly more nitrogen in tea leaves than in most liquid pot plant fertilisers that are formulated for healthy, balanced growth. ... Used tea leaves are best added to your compost heap.