We are a tea loving country and licence to excessive consumption are articles about the tea leaves being magic wand for plants . Its a semi myth that Tea contains nutrients and trace minerals that promote healthy growth in plants. Without looking at scientific studies these green tips propose putting used tea leaves in garden/potted plants . I did that too and learned it the hard way that tea leaves make soil extremely toxic to most of the plants. You can see the photos of how a plant and soil is spoiled at the end of this post.
Why used(fallen tea leaves in plantation) spoil the soil?
Reason I-Tea being an Aluminium loving plant and takes up much more aluminium from soil. Tea plant concentrates aluminium more than many plants, and the amount absorbed by the plant can be highly variable, depending on growing conditions. More acidic soil leads to greater uptake of aluminium by the tea plant, especially if the pH is below 5. The tea plant prefers acidic soil and is typically grown in soil with pH ranging from 4.5-5.5, so these conditions are common in commercial plantations.
Dried tea leaves contain about 4.4% nitrogen, 0.24% phosphorus and 0.25% potassium. There is significantly more nitrogen in tea leaves, it is unlikely that much of the nitrogen in tea is actually available to plants. Other elements in tea are very harmful. It contains aluminium, fluorine and manganese, which are harmless to people but high concentrations in very strong or stewed tea retard plant growth. Aluminium in soil adversely effects most of garden plants making them yellow and stunted.
In a scenic plantation one can look at how clean the ground is under the plants .The reason being this toxicity which doesn’t allow weeds and other small flora to grow.
The method of brewing tea, and whether or not sugar is added, also influences how much of the metal is extracted into the brewed cup. A study in Mexico found that adding sugar to tea was found to greatly increase aluminium concentrations in the cup and was theorized that the chemical structure of sugar may be inducing the polyphenols in tea to release aluminium that had previously bound to these chemicals. However type of aluminium species (forms of the metal) in solution and its health impacts were not looked into.
Reason II- Tannic acid is a naturally occurring acidic substance in tea. While this may not be a problem in certain soils, depending on the pH level, tannic acid can lower the pH, creating an acidic environment that is unfavourable for some plants. Regular checking of soil pH is needed.
Plants that prefer acidic soil….
Plants that will do well with tea leaves and grow best with a low pH (acid-loving plants) include blueberries sweet potatoes, beans, tomatoes , broccoli and peppers (Capsicum). However my experience with tomatoes is that they can manage tea decoction/leaves only upto certain extent and that too not directly but composted ones. Could not find any study which links aluminium uptake by these food crops and its impact on productivity as well as human health. Lime tree survives periodic addition of composted tea leaves.
Addition of tea leaves/compost slowly changes the looks of the soil giving it ashy appearance . Soil is dead by then and plants wither away in it.
In garden azaleas and roses do well with periodic addition of tea compost. Evergreens like spider plants, dwarf snake plant ,aloe vera , jade plant and many succulents survive well with periodic addition of tea leaves. However they are not eatable hence their phytoremediation properties( soil cleaning), impact on human health and soil nutrition is not studied. It would we wise to keep the soil from such plants separated from food producing plants.
With Aluminium and Tannic Acid both it becomes very harmful to compost fallen leaves in plantation or brewed tea leaves at home. A little quantity periodically added to the compost is ok but regular addition of it in home compost makes it harmful for most of the garden plants as shown in my photo graphs. Even acid loving plants cant tolerate so much of aluminium. Its is also researched that as the tea-plant age they reduce the healthy micro biome in soil and lately research has been going on about regenerating soils fertility .
Never compost tea bags as most of them contain upto 25% plastic unless mentioned otherwise.
One can also add alkaline materials to soil periodically to reduce its acidity . An interesting start-up is working in this field of making alkaline materials available to farmers to maintain soil pH
Another way to avoid having used tea leaves is to use tea powders. A little of it in water makes a cup without worrying about composting. Currently this is available for green tea only.
Many ways are there to use up the brewed tea leaves without concentrating aluminium in garden soil or compost. Some of them will be discussed in my next post.