Have you read this article?

https://www.gardeningknowhow.com/composting/ingredients/coffee-grounds-gardening.htm

BIG difference between used and unused/fresh grounds!!

Some time ago I read an article about coffee grounds being illegal to use in the garden, in England, because they thought the caffeine adversely affected bees and their ability to fly. I can't find that article back, but this is amusing: https://www.independent.co.uk/property/gardening/no-coffee-for-slugs-8081384.html

Interesting article windymess.

I looked it up. Windy is referring to a study that was done in the UK with honeybees. They added caffeine to fragrant sugar water. There was a different fragrant non-caffeine sugar water as a control. The bees liked the caffeine water best and returned to it more often than the other water. If I read it correctly, it didn't help with honey production, but the bees were more likely to "tell" the other bees in the hive where to find the caffeine laced water. They implied that the bees were more "scattered" on the caffeine.

Imagine that.

bkay

I put my used coffee grounds in the garden to deter slugs and rabbits. I don't really know how well it works but I just put some out, now that the snow has melted, and I haven't seen a rabbit yet. With rabbits (and deer) you have to change up the taste/smell repellents during the summer. I will apply Milorgranite in a week or two - works best right after rain. I think I will start spraying as soon a s the snow melts as there is no rain in our immediate forcast. Sorry, a little off topic with the rabbit thing. I don't have many slugs.

Bkay, there is no scientific proof slugs are deterred by coffee grounds, here's an interesting 'study'.

Pieter

Good sleuthing bkay! I’m not sure that is the article I read, but mine was based on that info. I’ll keep searching. The one I read provided some interesting “food for thought” and laughter at our dinner table. And the discussion may have crossed over into the political realm.

Dave- if I can find the article I can answer your question. I thought that perhaps there was an inference that the bees were ingesting caffeine from the pollen of flowers mulched with coffee grounds.

Just to set the record straight- I’m certainly not trying to advocate the position that the coffee grounds are harmful! We drink loads of coffee in this house, and I’ve been known to collect up the grounds and work them into the garden soil - anything to improve the texture of this clay! I haven’t been doing that lately because I just haven’t wanted to bother collecting it (too many other things to pay attention to). And, my soil has improved dramatically anyway, with mulching and planting.

I’ve planted lots of wildlife-friendly plants, including two linden trees (which the bees adore). But I’m not worried that a little caffeine (IF they even get any) is going to harm them or their social structure and activities.

To be honest- I’m still chuckling over that old Chevy Chase SNL skit where he quoted a study proving that “white mice cause cancer.”

In my profession I have to teach students to rely on the quality of scholarly and peer-reviewed research. However, I’m very skeptical (trying not to be cynical) about almost everything I read and hear these days. To this point I’ll share this recent article from the WSJ: https://www.google.com/amp/s/www.wsj.com/amp/articles/how-bad-is-the-governments-science-1523915765

bkay- life is too short to drink bad coffee, and if I were you, I’d use the coffee grounds however you like. Don’t know if it will help in any way, but I certainly don’t think it will hurt.... just sayin’

I just took it out and spread it over the yard. I thought at first it might harm the bees. Once that concern was out of the way, I guessed it couldn't hurt.

bkay

Good for you, bkay, it will blend in with the dirt/mulch after one rain. Anything is better than putting it in the trash. I either compost it or put it directly in the garden. We put way too much food waste in the trash. If nothing else it will add a small amount of Nitrogen.

I was surprised to read here that slugs were not bothered by coffee grounds. But there could be a different effect if the grounds are wet or dry, don't you think? Anyways, there is no mention of whether there is any effect on squirrels and their digging in pots. So I'll try that one!

I don't think there is any cure for the squirrels other than a shotgun. I believe they think there is a nut under that greenery, so they dig it up. It's my experience that they do that with smaller plants in the spring. In the fall, they bury their nuts in the pots because they are too lazy to dig a real hole. Potting soil is much easier.

bkay

Fresh coffee grounds are very acidic.....they could alter the soil pH. And they tend to become hydrophobic (resist wetting) if applied as any kind of mulch. Used coffee grounds are nearly neutral afa pH is concerned (all the acidity is leached out with the liquid coffee) but they can also become hydrophobic if allowed to dry out. And they do deter slugs and snails.....not because of the caffeine but because the mollusks dislike the sharp edges of the grounds.

Personally, I would never put fresh (unbrewed) grounds in my garden but compost them first. YMMV

You probably don't live in an area with high alkalinity, either. Anything that makes my dirt more acid is good.

You could spray lemon juice on the dirt in my yard and a week later it would be very alkaline again. Actually, they call the area where we live, "White Rock".

bkay