Coffee

While doing a little research on Coffee, I ran across some information that indicated coffee can be a good pesticide.

"In tests, caffeine distorted behavior, depressed food consumption or inhibited reproduction of tobacco hornworms, mealworms, milkweed bugs, butterfly larvae and mosquito larvae." (But no mention of squash bugs)

https://www.nytimes.com/1984/10/07/us/caffeine-is-natural-insecticide-scientist-says.html

The same information indicates that coffee growers douse the coffee plants with heavy pesticides to promote better production.

https://www.organicconsumers.org/news/pesticides-your-coffee

How much of the pesticides remain in the grounds after brewing is unknown. It depends on the chemicals used, how it is processed/brewed, water used, etc.

For those who stay up late reading permies.com articles, this might be of value:

https://www.caffeineinformer.com/strongest-coffee-brands

Some info on nutritional value of coffee for plants:

https://www.sunset.com/garden/earth-friendly/starbucks-coffee-compost-test

Used coffee grounds vs Neem Oil

Used coffee grounds *MAY* work similarly to Neem Oil in how it affects garden pests.

About Neem Oil: it is a fungicide that may kill Mycorrhiza Fungi whereas used coffee grounds may not. I am unable to find information pertaining to Neem Oil and beneficial fungi.

My husband drinks organic coffee, and we use that for mulch. I usually save it for my strawberries, as they love the nitrogen in it, and the ground also help repel slugs and bunnies. It's not a perfect prevention, but it sure helps!

Interesting research, Kai. Since I live in coffee country (mostly arabica varieties), plus grow some in my own farm, I have easy access to coffee. I think it might be interesting experimenting with it to see if it actually is useful for controlling pests of any sort. But would that caffeine be detrimental to beneficial things too? I'll have to keep a watchful eye when I experiment.

As for coffee grounds, I've been using them for years now. They definitely improve my soil, plus are part of my homegrown fertilizers. I get a five gallon bucket of spent grounds weekly and would gladly take more if they were easily available to me. I use them in making my compost, plus rototill them directly into the soil when the timing is right. I haven't noticed anything detrimental about them, at least not in the way that I'm using them.

Su Ba, I have used weak coffee water in a sprayer before. I do not have empirical evidence pertaining to the effectiveness of the solution as a pesticide but in my experience it did seem to repel squash bugs when sprayed on them and the tomato plants. Yes I had them pretty bad on tomato plants one year since there was no squash around for them to eat.
Lately I found a few squash bugs on my zucchini plants.

I am mauling it over as to try them again or just skip it and just use neem oil and risk killing my good M. fungus.

Caffeine and seed germination
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1276408/?page=1

Have you tried using wood ashes mixed with coffee grounds (and wet them) as a fertilizer?

I use wood ashes in my compost. Since up until recently I had to deal with acid rain, wood ashes were an important part of my garden soil amendments, I incorporate compost into the gardens between each crop. With long term and perennial crops, it gets used as a mulch and top dressed with fresh grass clippings. Thus wood ash is constantly being applied in small amounts.

I plan to try some coffee spray to see what happens.

Su Ba wrote:I use wood ashes in my compost. Since up until recently I had to deal with acid rain, wood ashes were an important part of my garden soil amendments, I incorporate compost into the gardens between each crop. With long term and perennial crops, it gets used as a mulch and top dressed with fresh grass clippings. Thus wood ash is constantly being applied in small amounts.

I plan to try some coffee spray to see what happens.

Here is the permies thread regarding the mixing of wood ash and coffee grounds:

https://permies.com/t/15756/Mixing-Wood-Ash-Coffee-Grounds

I haven't tried it yet. Haven't had the time to experiment (dealing with squash bugs and too much rain)

Speaking of wood ash, we discovered a way to neutralize the alkalinity without coffee grounds. We mixed in distilled white vinegar + some water to mimic the acidity of the coffee grounds. I do not recommend this anywhere NEAR your house!

I add coffee grounds to compost & worm beds. I see it like this ... it helps the soil so therefore the plants are healthier. Since insects generally prefer unhealthy plants the pests become less of an issue. If I had a source for large amounts of organic coffee grounds I would add a lot more.

Mike Barkley wrote:I add coffee grounds to compost & worm beds. I see it like this ... it helps the soil so therefore the plants are healthier. Since insects generally prefer unhealthy plants the pests become less of an issue. If I had a source for large amounts of organic coffee grounds I would add a lot more.

Where to get used coffee grounds in general:

https://www.thespruce.com/where-can-i-get-free-coffee-grounds-for-my-garden-1388586

Perhaps Johnson City TN, Maryville TN, or Asheville/West Asheville NC might have some? Gatlinburg? Similar?

All fast food places have them. All 'sit-down' places have them. Mainstream gas stations/truck stops have them.


I got the 4 tons for my Hugelgarden from Starbuck's and gas stations.

Took about 6 months too with starbuck's being the main source for the bulk of them.
Starbuck's has a first come, first served policy.

I averaged between 50 and 350 pounds of used coffee grounds each time I made my rounds.

The best time available for them is in the fall/winter time when there is less competition for them (personal experience).

Update:

I found a pretty easy way to kill squash bugs.

Plain water mixed with dish soap (in my case generic dawn).

First I waters the plants heavily to drive them out of hiding.

Used a spray with 1/2 cup soap to 1 gallon of water and sprayed the bugs and surrounding area a bit (NOT HEAVY).

Bugs dies within minutes.

I figured that if it can be used safely after the Exxon spill and not harm the environment it should be OK for killing bugs.

Neem oil is very hard on the plants and nearly killed 2 of the 3 I have.

And it didn't kill the bugs right away either.

I cannot find 'organic' dish soap locally so was stuck doing it this way.

Update - squash vine borers killed 2 of my zucchini plants and damaged a 3rd one. Replanted them from seeds again.
Hoping no more problems.
Also those pesky squash bugs are laying eggs on my Okra plants and other plants too!

Sneaky little devils.

I will spray them again if it cools off enough.