Are Tea Leaves A Good Fertilizer? Do Not Hurt Your Plants!


Should you consider tea as fertilizer? Every time you brew yourself a nice cup of tea, you will end up with a fair amount of used tea leaves that you may or may not have any use for. Further, you might have a tea that you do not enjoy or has long passed its prime.

How can you put the tea to use that you could not do anything with other than throwing it out? Using tea leaves or tea that has been left out too long as fertilizer for your various plants might be an option.

Tea As Fertilizer Good For Plants

SHORT ANSWER – Can You Use Tea Leaves For Your Plants?

Yes, both tea leaves and infused tea can be used as fertilizer for plants. Usually, tea is a very good natural fertilizer and provides valuable nutrients for most plants. However, there are types of tea generally not suitable as fertilizer and some plants do not respond well to tea.

There are various types of plants and tea varieties. Because of this, no answer will be fully correct for every plant and/or tea. While researching this topic, I have come across various points that speak for and against the usage of tea as fertilizer.

Is the type of tea you have a viable fertilizer for the plants you own? This post addresses various methods and applications with their advantages, disadvantages, and mistakes you should avoid to keep your plants alive.

What Nutrients Are In Commercial Fertilizers?

To fully understand whether tea can be a viable fertilizer for your plants, we need to take a quick look at commercial fertilizers. What is the exact purpose of these and what are the nutrients contained?

The most common ingredient of fertilizers are chemicals that contain nitrogen, phosphorous and potassium. Fertilizers of this kind are referred to as NPK fertilizers. These are the primary nutrients that plants need to grow and which are provided through the soil. 

The “Big 3″ can have an immense effect on your plants and are often one of the biggest expenses in the tea industry. (Source) Ironically, the nutrients contained in the tea that has often been grown utilizing NPK fertilizers can again be used as fertilizer without the need for additional chemicals.

Contents Of Common NPK Fertilizers

Commercial fertilizers will contain a given ration of Nitrogen, Phosphorous, and Potassium given in the form of N-P-K. For example, a general-purpose fertilizer can be 15-15-15, which means that the fertilizer contains 15% of each element. 

In spring, plants will have higher growth and a higher need for nitrogen. Fertilizers will therefore often contain more nitrogen like 16-8-8. The nutrients vary for different plants and seasons.

For example, fertilizers for tomatoes and flowers often contain higher ratios of phosphorous being labeled 10-12-10 and 10-14-8 respectively. This is supposed to allow the plants to develop more and larger petals and fruits.

This means that even though most fertilizers contain all three big nutrients, the effect may vary depending on the season and type of plant you have.

Other Chemicals In Commercial Fertilizers

It is not common for commercial fertilizers to contain additives that slow the release of nutrients to the soil. This will make the fertilizer last longer and prevents the oversaturation of the soil.

Additives of this kind are only necessary because NPK fertilizers contain very large amounts of chemicals that are not naturally contained in the soil with such large concentrations. With natural fertilizers, these additives are not necessary.

Furthermore, some fertilizers contain chemicals that will stimulate the growth of the plants. While these will cause the plants to grow larger and faster, most people will not need any of these.

What Makes Tea A Good Or Bad Fertilizer

Tea contains various chemicals that contain potassium, phosphorous or nitrogen. This will generally render tea both in leaf form and in brewed form as a viable fertilizer.

The nutrient levels in the tea will vary depending on the type of tea, when the leaves were harvested, the fertilization of the tea plant and various other factors. Because of this, the answer to the amount of nutrients in tea is given as an average.

Which Nutrients Does Tea Contain

Not all tea leaves contain the same amount of nutrients. A study done on tea leaves from two different estates growing the tea in low and high altitudes reported the following nutrients for young and mature tea leaves. (Source)

According to the study mentioned above, young tea leaves and shoots will contain 4-0.4-2, which means 4% nitrogen, 0.4% phosphorous and 2% potassium in the dry leaves.

Older leaves contain far fewer nutrients and the value of using it as a fertilizer is not given. Dry mature tea leaves contain 2.5% nitrogen, 0.2% phosphorous and 1% potassium. This is close to half the nutritious value of younger tea leaves.

Remember though, that most teas are made from the younger tea leaves as these tend to taste the best. There are some mass-produced teas and bitter Pu Erh teas that are made with more mature leaves, but that is definitely not the norm.

The amount of nutrients in the brewed tea is naturally far lower than that in tea leaves. All of the above percentages were determined for dry tea leaves, not wet or even steeped tea. 

Brewed tea should not have any noticeable positive effects on your plants. There may be negative effects because of other chemicals contained in the tea, so it is most likely a bad idea to give leftover tea to your plants.

Are Pesticides A Problem?

Residual pesticides in tea can be a major problem if you want to use your used tea leaves or leftover tea as fertilizer. The European Union has set very high standards for residual pesticides and heavy metals in tea.

This has resulted in fewer tea producers adding pesticides in large quantities but teas without any pesticides are still very rare. For this reason, both tea leaves and brewed tea may contain some amount of pesticides.

Pesticides will kill both insects, animals, and plants with the right dose. The pesticide contents in tea leaves and their infusions are not high enough to kill most plants. But be careful! Some plants are more sensitive to the pesticides in your tea than others.

If you want to use tea leaves or brewed tea as fertilizer you should take some care and not go overboard at first. Even though the pesticide levels in the tea you drink are considered safe for human consumption, your plants may not be able to survive.

But as with most things, the dose makes the poison. Your plants should be safe as long as you start with small amounts of tea to see how the plants react. If there appears to be negative effects, your tea may not be a suitable fertilizer for the plant.

Be Aware Of Plastic In Tea Bags

Another thing to consider is the plastic content especially if you are considering using tea bags for your plants. Most commercially available tea bags are made from plastic.

The most common plastic which is considered safe to use with foods is PET. This type of plastic, a type of Polyethylene, does not decompose. So using tea bags directly is not a good idea and should be considered pollution if you use them for outdoor plants.

On the other hand, the tea without the bag may contain plastic anyway. Friction will cause microplastic to fall off the PET tea bag and settle on the tea leaves themselves. PET is not soluble in water and is not harm you as a person, though.

Caffeine And Other Organic Compounds Can Be Bad For Your Plants

Other compounds contained in both tea leaves and the brewed tea are caffeine and complex organic molecules. Some of these compounds can harm your plants.

Do you know why tea plants have caffeine in the first place? Caffeine is used as a defensive mechanism as caffeine is technically a poison. Tea and other plants produce various chemicals to protect themself from insects and other dangers.

Humans have adapted to caffeine and are even using this chemical to their advantage. This does not mean that your plants will be able to deal with high amounts of caffeine or other compounds of your tea.

Again, you should always test small amounts of tea before you start using it as fertilizer for your plants regularly. If you want to be completely safe, I would not recommend using tea as fertilizer.

Things To Know When Using Teas As Fertilizer

So both tea leaves and brewed tea can be added to the soil of your plants to help them bring you joy. Generally, tea can be considered good for your plants as long as that specific plant is not sensitive to caffeine and the tea is free from residual pesticides.

Is There A Difference Between Tea Bags And Loose Leaf?

Tea bags are often made from plastics that should never be buried in the ground. If you want to use used tea bags to fertilize your plants at home, you will need to completely remove the tea bag.

This will not completely prevent the pollution of your soil with plastic, though, as microplastic will get onto the tea leaves inside the tea bags due to friction. 

If you want to avoid microplastic for the good of your plants and your own good, you should opt for loose leaf tea instead or have a look at plastic-free teabags made from paper or fabric.

Should You Use Wet Or Dried Tea Leaves As Fertilizer?

Used tea leaves are wet, obviously. Is there any need to dry the tea leaves before using them as fertilizer for your plants? The NPK-contents of the tea leaves will not change if the water is removed.

Wet tea leaves are as good for your plants as dry tea leaves are. The advantage of using dry tea leaves is that you will be able to gauge how much NPK you are adding to the soil, because you can judge the content with the percentages given earlier in this post.

Are Broken Tea Leaves Better For Your Plants Than Loose Leaf Tea?

There is no real advantage to using whole leaf tea over broken tea leaves. The difference would primarily be the time it takes for all nutrients to be released, as whole leaf tea has much less surface area where water can extract the nutrients.

The difference is not noticeable and the result for your plants will be the same. One thing that may differ is the nutrient content, as broken-leaf tea often is made from more mature leaves, which in turn contain fewer nutrients than the younger tea leaves.

The Advantages Of Composting Your Tea Leaves Before Using Them As Fertilizer

Composting your tea has some advantages over adding the tea leaves directly to the soil. Just make sure not to add plastic to your compost pile, as plastic can not be decomposed.

What composting does for you is making the nutrients in the tea easily available for the plants you want to fertilize. On the compost pile, the organic matter is broken down to compounds that the plant can absorb and use to grow.

Without composting not all nutrients in the tea will be available to the plant. Furthermore, composting can reduce the caffeine and pesticide content while keeping the nutrients. Composted tea leaves are very good for your plants and should not have negative effects on any plant.

Summary Of Using Tea As Fertilizer For Your Plants

Tea leaves and brewed tea is quite rich in nutrients. Commercial fertilizers more often than not contain more nitrogen, phosphorous, and potassium than dried tea leaves do.

Tea that is made from young tea leaves generally contains more nutrients than tea from mature tea leaves. Tea is a viable option to fertilize your plants because teas are produced from younger tea leaves and is rich in nutrients.

The problem with brewed tea and tea leaves is the caffeine, pesticide and potential micro-plastic content of the tea. Micro-plastic can easily be avoided by not choosing to use tea bags that contain plastic.

To avoid hurting your plants, tea leaves should not be added to the soil in large quantities if you are unsure whether the plant is sensitive to the respective chemicals. You can easily test this by adding small amounts of tea leaves first.

The best way to use tea leaves for your plants is by adding them to the compost. Composting your tea leaves will allow for the breakdown of harmful chemicals that can potentially harm the plants.

Furthermore, the organic compounds are decomposed to molecules that are far easier for the plant to take in and grow with. Composting tea leaves will yield nutrient-rich fertilizer that has no negative impacts on the plants or the environment.

Tea leaves can be very good for your plants if you take some precautions not to hurt them. Do not go overboard by too many tea leaves to your plants. Avoid plastic and pesticides as much as you can and remember that composted tea leaves makes for a great fertilizer for your plants.

There’s a lot more to learn about tea! If you are looking for a good place to start, I highly recommend the book Tea: History, Terroirs, Varieties. You can check its current price on Amazon here.

Jens Friis

I am the author and editor of TeaSteeping.com, chemist and tea enthusiast. For many years I have been obsessed with tea, teaware, and tea culture. Always hunting for the next tea experience and learning more about this most delicious and diverse beverage.

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