Is it worth keeping coffee grounds and adding it to the soil when it’s needed? Not sure if this is something people do or not. Still new to growing!
I add them to my earthworms bin and use the worm castings as a top dress for my plants. 
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Coffee grounds will change the soil pH too much so most of us avoid using them.
As Beck said they are great worm food. I thrown them in the garden to feed the worms.
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They are also loaded with nitrogen.
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I’ve put them in the compose pile before.
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I have a little coffee stand up the road who loves to trade buds for spent grounds. Win win for all. They are high in nitrogen as all ready mentioned, but they do have some P and K. The average NPK for spent (brewed) coffee grounds in 2: .5: .5. They won’t burn plants when added to a soil mix. It’s a good addition during veg stage. I would not be heavy handed with them during bloom since they are heavier in N. I grow mostly outdoors now so I spread them heavy in the off season and lay off once the gardens are growing. When my beds were new I would top dress it more during the grow season.
A side note about coffee grounds:
I have noticed that when I use coffee grounds as a cap I never have rodents burrow into my fallow raised beds. If I get lazy and forget about it once, they always seem to have a party in my compost pits. Coffee grounds make great compost in a growing bed too. But what I found is you have to spread them out very lightly and stir them into the soil. If you don’t they will actually cake up and make a hydrophobic layer on top of your soil. This will prevent your plants from getting water to the roots. All your water will just runoff to the side . I believe there’s some sort of fungus that grows in the coffee grounds that makes this mat so thick and hard. It looks kind of like the dog vomit fungus if you’ve ever seen such a thing. Anyway the coffee grounds left in a mat are counterproductive in a growing garden. If you put them in a growing garden just make sure to scatter lightly and stir in. Also, used coffee grounds have a neutral pH. They are NOT acidic contrary to popular belief. All the acids in coffee are water soluble and goes with the water into the pot that we drink. The spent grounds test closer to neutral.
If I were adding them to indoor potted plant I would put about a half cup in the bottom (per gallon of soil) of the pot or pre mix it. You don’t want the hydrophobic layer on top in a pot.
Interestingly enough though, day-old coffee itself is a great liquid pH down. It test 4.5-5 ph depending on the type. It also has lots of tannins in it which is great for the soil. I used to acid buffer all my discus breeder aquariums when I needed acid water in fish breeding. If you fight high pH or KH in your water (like a well or limestone aquifer for your tap) day old pot o coffee is a great pH down. Try it.
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Unfortunately, I have!
And I’ve also seen the phenomena you’re talking about. A lot of convenience stores will give them to you if you ask.
We use them on the flower beds and grow some of the biggest REAL weeds you can imagine! 
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You can get them for free from any starbucks. Just go in in the AM and ask about grounds for gardens.
@An-Cap1776 Coffee grounds are full of nitrogen, need worms fungus and bacteria to break em down, you would use it in compost, then use the compost to make a tea.
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Outta likes but thank you for that info. I have a couple of aquariums that need softer water than my tap (I usually use Indian Almond leaves) but I will try the day old coffee!
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Good stuff
Not around seattle. There’s usually lines of people waiting for the grounds when they put them out. They are picked over clean. Yes in the AM. I’ve seen people even bribe the baristas to get the grounds. They are no secret in the Seattle area as an excellent garden amendment. I could not get them free anymore at least not reliably
And I usually get coffee gratis there. Bud karma goes a long way. “Hey that’s the coffee ground guy. He’s cool 
”.
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I used to use coffee grounds to kill lawn mushrooms , and since i use mykos my logic is why use a shroom killer in a benificial shroom filled medium
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I need to try some coffee grounds, i had some rodents digging up plants at night, because I’m outside trying to stay hidden I’m limited on things I can do, they have stopped after someone suggested using cayenne pepper, but I’m going to try some coffee grounds too , I don’t need to lose plant’s because of Rodents digging the up , I believe it’s field rats coming out at night digging up my Garden 
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I grow indoors in a 2x2x4 tent. Would this scenario apply to an indoor grower?
I top dress my indoor plant with worm castings, but I use living soil so probably already have some bugs in the soil.
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If you mean feeding worms for an indoor grow then yes.
Give the grounds a good rinse and work in a couple spoons of grounds into the top inch or two of the pot. Worms feed near the surface. Feeding them about every two weeks should be fine.
Coffee grounds are not mushroom killers. Coffee grounds are mushroom food. I know because I have used them to grow mushrooms. Not all fungus eat the ame thing but trust me when I say Trichaderma loves coffee grounds!
I think it works at killing lawn mushrooms by outcompeting the lawn mushrooms with competition from other myco colonies. I think it is out competing and diversity going on there rather then true mushroom killer. But that would be a good name for a band. The mushroom killers.
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Ooh - My mind went to “The Killer Mushrooms featuring the Coffee Grounds Brass Band”
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