Coffee grounds

I have found much on the internet about coffee grounds, about how places like Starbucks are only too pleased to get rid of the stuff and how gardeners are using it to good effect in compost piles, liquid feed and direct around plants as a slow release nitrogen source. Worms increase exponentially (in number not size!).

Our local Starbucks have a large tub with a sign saying “help yourself”.

I had always thought that coffee grounds could be too acidic in too high a volume and therefore toxic. Any thoughts? Does anyone else round up the coffee grounds from work and coffee shops and use it on their allotment?

OH collects them from work and I have used them this year as a base in the cold frames.  It is noticeable that we have had fewer slugs than in previous years when it was just weed suppressant fabric on the bottom, and those that do appear, travel around the sides rather than over the base.  The big slugs have completely left the cold frames alone .....

We also had slug damage on a few of the more tender courgettes - with centres being well chewed over night.  Surrounded with 6" of grounds they have recovered nicely and are off again.

I dont know if it is the texture or the caffiene or what it is, but they dont like it and the plants are loving the protection!