Coffee grounds as a medium. Anyone try it?

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I have access to an almost unlimited supply of coffee grounds and can't help wonder if it could somehow be put to good use growing weed. I've read lots of anecdotal articles about how great it is as an amendment as well as some scientifically back articles about how you should avoid it unless you can fully decaffeinate it (caffeine, it seems, evolved as a natural herbicide to block competing plants). Coco bricks ain't particularly cheap though and coffee grounds are on the acidic side which is good for where I live where everything is high pH. Anybody actually try using it as a main component?

[Rwise]

True if properly composted coffee grounds have good things in them, however they also contain caffeine and that is an herbicide. Herbicides hill plants, so the caffeine must be fully washed out to not harm the roots. Maybe if you got decaffeinated it would be ok, IDK, I toss them in the compost. Good luck!

[SoOrbudgal]

I agree with Rwise says about reuse

[Going2fast]

I compost all of mine. Do an experiment. Thoroughly flush enough to fill a planter, add lime and perlite, plant a seed and see what happens. Should be a good base providing the caffeine is gone.

[dilvish]

I compost all of mine. Do an experiment. Thoroughly flush enough to fill a planter, add lime and perlite, plant a seed and see what happens. Should be a good base providing the caffeine is gone.

yep I would do the same. essentially any inert organic compound could work. I just tried composted wheatgrass...results were mixed but seemed to do fine

[bdeegan]

Cannabis and coffee are two of my favorites. I love this idea and might try it on the small scale next round. I’ll let you all know if it happens/works out!

Happy growing!

bd

[Cali]

Feed it to composting worms aka red wrigglers. Once they “poop” it out use it. It will be rich in nutrients and one of them is a famous one around here called Calcium.

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I am not prepared right now to try a more ambitious test using the coffee as the primary media but I did have two OrangeVelvet clones ready to pot so I decided to try a safer test (I don't want to lose either plant). Both pots have a 4:1 mix of Whitney Farms Organic Potting Soil and Pearlite. The plant in the white pot has coffee grounds added (4:1:1 ratio WFO:Pearlite:Coffee). I also mixed in 1 tsp mycorrizal fungi to both. Will post more pics in a week or so. pH of runoff is 5.98 (wo) and 5.90 (w).

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1 week later. Both show similar growth. The +coffee is ~1" shorter but started shorter. The "no coffee" (left) does seem healthier. Greener, perkier.

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Here's a better pic from the top showing the difference in color better. Also some curling on the plant with used coffee grounds added on the right. I think I am about to abort this experiment and try to nurse it to better health.

[Rwise]

Did you add anything for a PH up buffer? Looks to me like the PH is crashing. (and maybe a tad hot)

[click]

I just now flushed it with 2 gal. water (~5X the container volume). Initial runoff pH was 6.35 and it climbed to 6.8 by the end of the flush. Temperature is maintained between 60 and 75 in the box although I do see twice in the last week it spiked to 80 but only briefly. Humidity has varied between 30 and 60% over the same 7 days.

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Here are the temperature and humidity conditions in the chamber.

[3Berries]

I use coffee grounds on my evergreens. They like acid and nitrogen.

They grow soybeans around me. As it is a legume, it sets little sacks of nitrogen on the roots. This nitrogen makes the soil acidic. So the farmers always use limestone on the fields after soybeans.

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One of these things is not like the others; one of these things is kinda the same. Four months later the Orange Velvet that got the coffee grounds is still struggling...

[3Berries]

I had heard somewhere that caffeine will stunt the plant growth. I guess that's true.

But some interesting facts.

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/will-caffeine-affect-plant-growth.htm

Will Caffeine Affect Plant Growth?

What purpose does caffeine serve, other than to keep us awake? In coffee plants, the caffeine building enzymes are members of N-methyltransferases, which are found in all plants and build a variety of compounds. In the case of caffeine, the N-methyltranferase gene mutated, creating a biological weapon. For instance, when coffee leaves drop, they contaminate the soil with caffeine, which curtails germination of other plants, lessening competition. Obviously, that means too much caffeine can have a detrimental effect on plant growth. Caffeine, a chemical stimulant, increases the biological processes in not only humans but plants as well. These processes include the ability to photosynthesize and absorb water and nutrients from the soil. It also decreases the pH levels in the soil. This increase in acidity can be toxic to some plants, although others, like blueberries, enjoy it.

Read more at Gardening Know How: Will Caffeine Affect Plant Growth – Tips On Fertilizing Plants With Caffeine

https://www.gardeningknowhow.com/gar...ant-growth.htm

[SoOrbudgal]

That sucks guess it's another dang lesson, put some worm castings on it top feed, but I'd flush with Epsom salt first. Nice looking setup click