used tea leaves - Ask Extension
Used coffee grounds when not composted can harm vegetable garden plants, but I can find no definitive information about using used but uncomposted tea...
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used tea leaves #831276
Asked May 22, 2023, 9:03 AM EDT
Used coffee grounds when not composted can harm vegetable garden plants, but I can find no definitive information about using used but uncomposted tea leaves in garden soil. Most sources I've read seem to simply assume that tea leaves should, like coffee grounds, be composted, but I have not found any data/studies etc. that explicitly address the issue of directly putting used but uncomposted tea leaves into garden soil. Can you help?
Thank you!
Kent County Michigan
Expert Response
Del,
Thank you for using Michigan State Universtiy Extension Ask Extension with your composting question. First, I want to begin with the fact that Coffee grounds are not harmful around all plants and can be useful in certain circumstances. The primary concern is with the level of caffeine present and that is related to how much you are applying.. Caffeine can harm tender plants, houseplants, and seedlings. Trees, shrubs and mature perennials can handle sheet composting of coffee grounds. sprinkle about and mix into the soil.
The same is true for tea in considering caffeine inputs. However, tea leaves decompose much faster and are a favorite of worms because they are leaves. I had put tea bags into a worm bin on daily basis for many years before I advanced to a large outdoor compost bin. The worms would go for them before any of the other food scraps. Leaf worms love leaves of any kind.
The dried seed hulls from coffee beans take longer for the soil organisms to break down. Presuming you are applying a daily amound of coffee and tea to your gardens you should be okay if you apply near plants that can tolerate the caffeine. My dad had a red maple that he mulched with coffee grounds daily for years. No harm it grew just fine with no apparent ill effects.
If you are taking in the left overs from a local coffee/tea shop then I recommend composting first as this can be more than will decompose in a reasonable amout of time through sheet composting methods.
https://www.epicgardening.com/composting-with-coffee-grounds/
https://www.thespruce.com/using-coffee-grounds-in-your-garden-2539864
https://www.gardeningchannel.com/plants-that-like-coffee-grounds/
Thank you for using Michigan State Universtiy Extension Ask Extension with your composting question. First, I want to begin with the fact that Coffee grounds are not harmful around all plants and can be useful in certain circumstances. The primary concern is with the level of caffeine present and that is related to how much you are applying.. Caffeine can harm tender plants, houseplants, and seedlings. Trees, shrubs and mature perennials can handle sheet composting of coffee grounds. sprinkle about and mix into the soil.
The same is true for tea in considering caffeine inputs. However, tea leaves decompose much faster and are a favorite of worms because they are leaves. I had put tea bags into a worm bin on daily basis for many years before I advanced to a large outdoor compost bin. The worms would go for them before any of the other food scraps. Leaf worms love leaves of any kind.
The dried seed hulls from coffee beans take longer for the soil organisms to break down. Presuming you are applying a daily amound of coffee and tea to your gardens you should be okay if you apply near plants that can tolerate the caffeine. My dad had a red maple that he mulched with coffee grounds daily for years. No harm it grew just fine with no apparent ill effects.
If you are taking in the left overs from a local coffee/tea shop then I recommend composting first as this can be more than will decompose in a reasonable amout of time through sheet composting methods.
https://www.epicgardening.com/composting-with-coffee-grounds/
https://www.thespruce.com/using-coffee-grounds-in-your-garden-2539864
https://www.gardeningchannel.com/plants-that-like-coffee-grounds/
Hi Beth,
First, thanks for the quick response - this is really a great service that you provide.
We drink quite a bit of tea, and it usually gets (partially) composted along with our other kitchen scraps. We've done that for years, but we also frequently just dig kitchen scraps - including tea bags and leaves - directly into beds that are being prepared for vegetables. I knew that the caffeine was the problem with coffee but that there was significantly less in tea (anywhere from 15% to 50% of the coffee numbers depending on who you believe). That made me wonder if there simply was no problem of any sort with tea leaves, but could find only a few places that even mentioned tea at all, and if it was mentioned it was generally at least implicitly assumed to be composted.
Your reply was helpful.
Thanks again.
Del
