# Coffee grounds as plant fertilizer?

**URL:** <https://boards.straightdope.com/t/coffee-grounds-as-plant-fertilizer/125253>\
**Category:** Factual Questions\
**Created:** [August 23, 2002, 4:32pm UTC](https://boards.straightdope.com/t/coffee-grounds-as-plant-fertilizer/125253 "2002-08-23T16:32:46Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Patty\_O\_Furniture](https://avatars.discourse-cdn.com/v4/letter/p/96bed5/32.png) [@Patty\_O\_Furniture](https://boards.straightdope.com/u/Patty_O_Furniture)\
**Post date:** [August 23, 2002, 4:32pm UTC](https://boards.straightdope.com/t/coffee-grounds-as-plant-fertilizer/125253/1 "2002-08-23T16:32:46Z")

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At my friend’s house I noticed a fine dark granulated material in all of his potted plants. He said that he dumps coffee grounds straight into the pots, and sure enough all of his plants look just great. I would imagine that would make for an awfully acidic soil. I’ve got quite a few droopy plants that could stand to be perked (heh) up. Maybe a shot of joe is what they need?

What is it about coffee grounds that plants like?

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**Author:** ![breaknrun](https://avatars.discourse-cdn.com/v4/letter/b/bbce88/32.png) [@breaknrun](https://boards.straightdope.com/u/breaknrun)\
**Post date:** [August 23, 2002, 5:18pm UTC](https://boards.straightdope.com/t/coffee-grounds-as-plant-fertilizer/125253/2 "2002-08-23T17:18:35Z")

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IANA horticulturalist but a Google search shows some commercial products using coffee grounds and from [this tips page](http://www.emilycompost.com/tips%202.htm):

> [@](#):
>
> Coffee grounds help diminish alkaline soil. Worms love to help decompose them.

Also from the above site, caffiene is considered to work as a herbicide.

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**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\
**Post date:** [August 23, 2002, 9:34pm UTC](https://boards.straightdope.com/t/coffee-grounds-as-plant-fertilizer/125253/3 "2002-08-23T21:34:49Z")

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Coffee grounds aren’t acidic, although you’ll find many sites that say they are. From [a FAQ at GardenWeb.com](http://faq.gardenweb.com/faq/lists/soil/2002015354019975.html)

> [@](#):
>
> \*Roasted coffee is fairly acidic, but it appears that almost all of the acid is water soluble and is extracted during brewing. Used grounds have essentially neutral pH, although the coffee beverage produced is rather acidic.
> 
> The measured pH of used coffee grounds was 6.9, with a significant amount of buffer capacity\*

They love coffee grounds over at GardenWeb. In addition to the above link, try [Coffee Grounds](http://forums.gardenweb.com/forums/load/soil/msg062154182867.html) and [Coffee grounds as a straight fertilizer??](http://forums.gardenweb.com/forums/load/organic/msg0609243015032.html)

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**Author:** ![rostfrei](https://avatars.discourse-cdn.com/v4/letter/r/7bcc69/32.png) [@rostfrei](https://boards.straightdope.com/u/rostfrei)\
**Post date:** [August 23, 2002, 10:38pm UTC](https://boards.straightdope.com/t/coffee-grounds-as-plant-fertilizer/125253/4 "2002-08-23T22:38:35Z")

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My grandmother used to “water” her house plants with leftover, cold coffee. She had the most gorgeous plants I’ve ever seen.