I don’t drink much coffee and I don’t have a cat but when I walk up the street sometimes I bring home a big bag of coffee grinds and kitty litter. Spent coffee grinds, that is, and 100% clay, for my worms and my garden.
I mix some clay into the coffee grind before putting it in the worm farm. Coffee alone can make the farm too hot and smelly as it decomposes rapidly. I’m not sure if it would prevent my worms from becoming caffein addicts but too much coffee is not healthy for anyone, is it?
I also use the clay to anchor pot plants in my fish tank – potting mix would simply float off. Make sure you get 100% natural clay.
The coffee grinds can also be scattered onto garden beds under acid loving plants like the Camellia, or into the compost bins to speed up decomposition.
Most baristas would give you bags of spent grinds happily (except one at Starbucks but surely even worms would reject their coffee). Try not to ask while they’re busy. My man said to see him near five o’clock when he knocks off and I wouldn’t dream of bothering him at any other time.