Certain supplements of folk origin are increasingly and loudly criticized in society. Tea leaves, which "forum members" recommend using everywhere: from a flower pot to a vegetable garden, have not escaped criticism either.
But in this regard, everything is not as cloudless as people say.
We can talk about some benefit if it is dry tea. It partially contains calcium, magnesium, potassium and other useful elements.
Another important point is that the brew should be without additives and flavorings.
It can be used as mulch, even in a flower pot, when the soil needs to be made lighter, looser and airier. Mulch is especially helpful for moisture-loving crops in hot and sultry weather. However, you can add tea leaves after watering.
You can use black and green tea leaves.
If we are talking about ferns, azaleas, hydrangeas and cacti, then the brew will not cause any particular harm. The same applies if you need to water other plants that normally tolerate hard water and the presence of tannins in it.
But such feeding will bring nothing but harm to violets.
It is worth remembering that tea leaves acidify the soil and can lead to the formation of mold, fungus and root rot.
It can cause black flies or fungus gnats to appear.
Moreover, you cannot water flowers with tea leaves if sugar has been added to them.