[laputan_machine]

I keep my grounds but I've found whenever I use them on indoor plants it grows mould on it within a day of watering the soil. Outside plants / veg don't have this issue -- have you come across this before? I keep my used grounds in a conservatory, they're very dry when I use them, although I guess not dry enough...

[explorigin]

Direct UV light inhibits surface mould growth. This is why you don't see it (as much) outside.

[MAGZine]

grounds are fantastic in an active composting environment. they make really great, nutrient-rich soil. less so for indoor plants with their tiny, relatively sterile environment. Indoor plants usually suffer from two problem wrt coffee grounds: a "that's going to mould," problem and a "that's too acidic on it's own to be useful," problem.

[laputan_machine]

Thanks, that actually makes a lot of sense. So I've been using them wrong, whoops! I guess I should get myself a little bin to compost stuff in

[hkt]

Mix them with a bit of soil rather than leaving them on top.

[muttled]

How old is your soil? Mixing in some fresh soil with the grounds might be a solution since a lot of the micro-organisms in soil that would break that down and eat the mold degrade over time.

[swasheck]

i live in an arid climate and just air-dry and then put them in a container for later use. however i also only use it as part of the soil for outdoor gardens. my grandmother’s “recipe” was topsoil, sheep manure, coffee grounds, and banana peels and that’s worked out for me too

[cmrdporcupine]

You have to compost first, really.