Moldy coffee grinds - still good to use?

[Vlk]

Hi there, I am a coffee lover and got a lot of leftover coffee grinds, that I was saving up to use later to enrich the soil in the pots. Unfortunately, it wasn't properly layered and there was a wet lump in the middle that got moldy. I broke the whole thing down, made it fine again and spread it on the sun to dry up. Is it still ok to use even when it was moldy like that?

[1rainman]

In my experience once you put the coffee grounds on the dirt eventually it all molds for a couple weeks as part of the decomposition process. Plants seem to grow really well with them though. It provides a lot of nutrients and caffeine is a natural insecticide. Not saying it is going to be potent enough to get rid of all bugs but some of the trace amounts of caffeine leftover helps control them a little.

[Vlk]

In my experience once you put the coffee grounds on the dirt eventually it all molds for a couple weeks as part of the decomposition process. Plants seem to grow really well with them though. It provides a lot of nutrients and caffeine is a natural insecticide. Not saying it is going to be potent enough to get rid of all bugs but some of the trace amounts of caffeine leftover helps control them a little.

Thank you for sharing your experience! I was thinking that this might be a natural process. Good to know that it's safe! And the caffeine being a natural insecticide is a nice bonus I wasn't aware of, that's great!

[Oolie]

It's perfectly fine, it means your nutrients will be released more quickly. Usually the grounds in my compost end up all full of hyphae within a week or two, then if kept humid mushrooms will appear.

[elouicious]

I use moldy ones all the time-

Steam sterilization opens them up to being colonized with mold quite easily- usually the ones growing on it are not harmful to plants but I would make sure to use either a mask or work outdoors to make sure you don't get anything nasty in your lungs!

[brian]

I also use moldy coffee grounds, and have for years

[Vlk]

Amazing, thank you all for sharing your experience! I dried the grounds, packed them, and now they are ready to be used.

[Plantinyum]

Hi team, one question regarding the topic. Are u adding the grounds as a component of the soil ,or just spread them on the surface ?? Thanks !!!

[RodneyS]

I place used coffee grounds in the compost pile and/or worm composting bin.

[elouicious]

Top-dressing for me

[Fygee]

I only recommend it for compost. Coffee breaking down saps nitrogen from the soil, typically at the top level where the feeder roots are. Once broken down they'll put nitrogen back in, so they're much better composted.

Caffeine in high enough levels will also stunt or kill plants. It's an evolutionary defense mechanism to cut down on competition from nearby plants. Composting will also minimize or remove the caffeine.

[brian]

I use them as a portion of the "fines" part of my soil mix, along with peat, compost, etc. 

I leave the grounds outside to get rained on for a few months before I use them, to leach out any remaining caffeine.

[bbudd]

I add them to my liquid fertilizer mix just before i set it to ferment and add the bubbler
Plants love it

[Plantinyum]

Thank u all for sharing your experience and have a nice day !!

[1rainman]

Caffeine and Nicotine are deadly to insects but relatively harmless to plants. They even make synthetic Nicotine that they feed to plants and keeps them insect free for a year, but its not for anything that people will eat. They act on your central nervous system. An insect has a simple nervous system so it overloads it and kills them. In humans it just gives them a buzz or energy boost. Plants don't have a nervous system like that so there isn't any real effect. Of course any compound in high enough doses can have a negative effect. High enough doses of table salt can kill plants but in low doses actually provides micro nutrients. Whenever I put coffee grinds on a plant I just see it perk up. I have not seen any negative effects. I suppose if one were to use it in high enough doses constantly maybe there would be an issue.

[1rainman]

I actually tried to make a nicotine insecticide out of black and milds before. Native Americans grew tobacco primarily as an insecticide. Caffeine and Nicotine can also kill parasites in humans or animals (for instance kill worms in dogs). So smoking actually does have some benefits. But not only did my efforts not harm the plant, it didn't do much to the insects. The amount of nicotine in a few black and milds is not enough even for a small potted plant. It basically washes out, gets diluted, breaks down etc. Its similar with coffee. The amount going into the plant is almost non-existant. The interesting thing about these compounds though is they can linger in the plant for a long time only very slowly breaking down. The synthetic Nicotine they treat a tree with it and its good for a year. Though its much more potent than natural nicotine. So I suppose over a long period of time constantly dosing the plant would be the only effective way to get a decent amount into the plant. An occasional dumping of grounds most caffeine will go in the soil and eventually wash out of the soil with next to nothing going into the plant. Plants will absorb anything in the soil but not in large doses. They primarily just absorb the water and nutrients they need.