Mother Earth News Blogs > Organic Gardening

Organic Gardening

Get dirty, have fun and grow more food with great gardening tips from real-life gardeners.

Help Us Confirm: Do Spent Coffee Grounds Protect Cabbage Plants?

By Cheryl Long

Tags: cabbage, pests, coffee grounds, eggshells, question to readers, readers' research,

Last year, reader Mindy Moore reported that a mixture of coffee grounds and eggshells protected her cabbages from pest damage. Crushed eggshells are generally thought to repel slugs, but using coffee grounds was not an idea we had heard before.

We would like to encourage you to try out this technique this summer and report back to us. The caterpillars of several kinds of moths often damage cabbage, broccoli and other brassicas. Bt, an organic insecticide, kills the worms, but spent coffee grounds would be a much cheaper and greener option, if it works consistently. We’re thinking that the odor from the coffee grounds probably makes it difficult for the moths to locate the plants.

Give it a try — just sprinkle the grounds around your plants, and let us know how it works out. Post your report in the comments section below.

Cheryl Long is the editor in chief of MOTHER EARTH NEWS magazine, and a leading advocate for more sustainable lifestyles. She leads a team of editors which produces high quality content that has resulted in MOTHER EARTH NEWS being rated as one North America’s favorite magazines. Long lives on an 8-acre homestead near Topeka, Kan., powered in part by solar panels, where she manages a large organic garden and a small flock of heritage chickens. Prior to taking the helm at MOTHER EARTH NEWS, she was an editor at Organic Gardening magazine for 10 years. Connect with her on .

6/20/2009 2:43:26 PM

Well I have to say I am disappointed with the coffee grounds as a slug deterrent. From the comments I read I had high hopes, particularly since the people from Washington raved about the success with coffee grounds. We have a lot of slugs here in British Columbia and while they are not nearly as big as those in Washington or on Vancouver Island, they certainly inflict a lot of damage on a garden. Several years ago I finally gave up trying to grow strawberries for more than just the resident slug population but thought that since I had moved to a new location and am using a raised garden planter bed that I would give them another try, especially after reading the coffee/coffee ground ideas. It did seem to work on the strawberries although I have to say I really didn't notice a lot of signs of slugs there in the first place so I thought that being proactive was the key and I had kept them at bay right from the start. My lettuce was quite another story. These very, very tiny little slugs, not much bigger than a pin head, have managed to completely decimate all twelve of my lettuce plant in less than a week despite my vigilance. I have watched these little beggars crawl right over the coffee grounds to get to the lettuce plants. I have sprayed them with a full strength solution of coffee (and I like mine fully leaded, strong and black)and they have kept on going. I am quite disappointed to say the least. Looks like I will have to resort to growing lettuce in containers if I hope to get any of it for myself.

annie hamric
6/14/2009 8:16:56 AM

I have used coffee grounds, egg shells and tea bags in my garden box for years. People who have problems with deers, rabbits or other animals eating their plants can be assured that they don't like the smell. I've never had any problems with animals getting into my garden. Earth worms like the grounds. I do not use any pestisides in my garden and the only things I have found is a tomotoes worm and parely worms. I just collect the grounds and egg shells for about a week, dig a hole and put them end. It seems to work real well.

tom marsh
6/6/2009 2:06:41 AM


the brays
5/30/2009 3:38:59 AM

My parents live on the coast of northern Washington State. As you all may know, they get a lot of rain and they have a LOT of slugs. Coffee grounds are great for deterring slugs. The high acidic content of the grounds keeps them from crawling through it. As for repelling other bugs, I have witnessed aphids, spiders, ants and several other creepy crawleys avoid a coffee ground covered area like the plague. I am not sure whether it is the smell or the acidity or perhaps both. As far as I am concerned, its a proven pest protector.

gregg stokes
5/21/2009 7:15:54 PM

I do not know abour coffee grinds keeping bugs away from cabbage but it did run ants out my strawberry plant and that plant has put flowers back oon where the other two plants have not.

5/12/2009 12:06:05 AM

I have heard that this method works: 1) Steep the used coffee grounds or brew them a second time in the coffee maker. This produces a weak coffee liquid. 2) Use the liquid to spray on the plants. This keeps away pests and also promotes growth. Has anyone else tried this?

5/11/2009 8:33:27 AM

Please dan't call Bt an "organic" pesticide. Yes, it comes from a bacterium (Bacillus thuringiensis), but that's where any links to green-ness end. It is the basis behind the genetically engineered crops that Monsanto is pushing onto farmers worldwide (Bt-ready cotton, corn, etc.) Thanks to these crops, which can survive caterpillars, the incidence of other pests is now increasing, and resistant strains of caterpillars and other bugs are developing. In addition Monsanto is screwing over small farmers by engineering non-proliferation into their seeds - i.e. farmers have to buy new seeds every year instead of re-using the seeds generated by their annual crop. This is the antithesis of green!

5/8/2009 12:01:42 AM

I've often used coffee grounds and made my own compost tea for my little green friends and they love it. We're fortunate to own a family diner with plenty of coffee loving fools in the morning to give me my grounds. I have read lately of using used tea bags. Just sprinkle the loose tea in the soil while planting and let it work it's magic. I think I have a new experiment on my hands!

lisa soliz
4/28/2009 9:33:10 PM

If snails in the dirt are killed by the caffiene in the Coffee grounds or tea bags, wouldn't earthworms also be affected?

4/25/2009 8:49:47 PM

The coffee grounds work because caffeine can repel or kill snails. It's been scientifically proven. "In preliminary experiments, conducted in a research greenhouse in Hilo, two-striped slugs (Veronicella cubensis) were allowed to bury themselves in soil in pots, then the soil was wetted with a 2% solution of caffeine in water. After 3½ hours only 25% of the slugs remained in the soil, and by 2 days all of the slugs were gone, with 92% dead."

4/25/2009 7:00:11 AM

I have used both coffee grounds and egg shells for some time now. Coffee is good for the soil, and at a young age learned from an avid gardener that the grounds atract benificial worms. Egg shells, washed, dried, and crumbled to small pieces scratch soft skinned pests while providing micro-nutriants to the soil. In fact, I have a bunch more shells and a tub of grounds to put in the garden today. I use them mainly around my tomatoes and cabbage. So far, so good.

4/24/2009 8:20:12 PM

I have always used both coffee grinds and tea with the eggshells. My grandfather did it, so I do too. I always understood this was both as a slug deterrent and as fertilizer.

4/24/2009 12:37:49 PM

Both of my grandfathers, maternal and paternal, used spent coffee grinds and eggshells. They were the old time "family farmers." I never knew why they used this combination but when I started my own gardening it was as much of the ingredients as the soil and seeds. I have never had a need for alternative fertilizer or pesticides/insecticides. I guess its is from the Coffee Grinds and Eggshell. I collect it everyday and my kids love to sprinkle it in the garden.

4/24/2009 10:42:16 AM

Coffee is a wonderful thing for your garden for two reasons the first is that it is high in nitrogen (fertilizer) and the second is caffeine, the slugs absorb it through their skin causing them to die. I don’t know about moths but I use it every year. Another tip is tea bags, put used teabags under your seedlings like tomatoes and it will fertilize them and retain water to keep the roots moist.

p l
4/22/2009 2:20:07 AM

I don't know about coffee grounds, but the master gardeners at the community garden said that putting down hog fuel keeps slugs away. Slugs are a major problem here in western Washington. So far in my square garden, I have seen no slug tracks. Maybe I can actually grow cabbage this year that isn't full of slugs. They say the wood chips in the hog fuel, like the egg shells, are uncomfortable to the slugs because they are pokey.