Do waste coffee grounds prevent weeds?


My morning ritual at some time started off by going to a coffee shop or convenience store to get a coffee.

Convenience store coffee were introduced in 2010 ish in Japan. The auto-freshly-milled-&-brewed coffee for 100¥ is great.

On a side note at said convenience stores. Ordering a small cup and accidentally pushing the big button fills the small cup nicely.


Waste coffee ground what is it good for? According to the internet a whole slew of things. Warding off Mosquitos, fertilizing, killing weeds by changing soil composition, many of which have never been tested.

repelling cats? and many more

Wiki has a small entry about it

I had my doubts. But as I had an abundance of waste coffee grounds I decided to toss them outside on top of some weeds/plants. Full disclosure, I do it out of laziness and chose the closest weeds to the door. The one in the picture, has a permeable tarp liner under the rocks that it broke through.

For about a year and a half I’ve done this weekly or whenever my used coffee ground piles up.

At first I poured them over a larger “plant” but the grounds would simply disappear in the greenery.

So I selected a new test candidate. A smaller type.


I checked again today after heavy rains. It seems to be healthier than ever.

  • My next test, as we have many slugs on the other side of the garden will be to dump the grounds there to see if there is any effect.

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