Spreading used coffee grounds kills slugs and a spray from soaking grounds kills aphids , but if you have a dog it is not a good idea to spread coffee grounds as it is poison for dogs as is cocoa husk mulch.

I've been spreading used coffee grounds around the hostas for years, in part as a fertilizer. I have not had much of a problem with slugs around the hostas, but don't really know if the coffee grounds played a role.

I've been saving and spreading used coffee grounds as a fert also. As a matter of fact,

I've been doing the Spring ammonia drench as well as amonia spot spraying. Slugs have been notibly more of a minimum this year...maybe the combination resulted in the down turn in slugs?

No doubt.

Thanks all for your feedback-- I really appreciate Jon I had no idea coco mulch was posionious to dogs. Luckily I have very high raised beds so it is not a problem. In an effort to be healthier I am stopping the coffee so I have plenty of grounds to use up. Thanks all!

The original research goes back to 2002.

http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1465&context=icwdm_usdanwrc

I'm surprised we haven't heard more about this over the past 13 years....

And here's some on the myth of coffee grounds:

http://puyallup.wsu.edu/wp-content/uploads/sites/403/2015/03/coffee-grounds.pdf

Pieter