Ask a Question forum: Coffee grounds and indoor plants care

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Name: D
London, UK
didacus
Jan 31, 2016 2:20 PM CST
Hello all,

I am having a lot of coffee grounds left overs from my coffee machine and I am wondering if I can use it for my indoor plants. If so, how should apply it? Do I need to mix it with the soil or can I just water it with the coffee ground mixed?

- Boston ferns
- Rubber plant
- Jade plant
- Evergreen shrubs

Thank you in advance.
Name: Elaine
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dyzzypyxxy
Jan 31, 2016 9:08 PM CST
I've used coffee grounds on my garden plants for years, but never tried it on a potted plant. You've got a wide variety of plants there with very different needs. I'd go slowly at first and see how the various plants tolerate the coffee grounds application. Maybe mix some coffee grounds into your water once a week or so and water with that.

Coffee certainly is a sterile organic additive and it's a great amendment for soil in the garden, but in a pot, you could get to a point of "too much of a good thing" fairly quickly. Any way you can compost the coffee grounds with the rest of your kitchen veggie and fruit waste? There are small composters available that can be used on a deck or balcony.
Elaine

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Name: Daisy
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DaisyI
Jan 31, 2016 10:19 PM CST
I would have a couple worries using coffee grounds directly on house plants:

1. A layer of coffee grounds could encourage fungal infections and protect and incubate insects

2. Coffee grounds are acidic. Some plants may not be happy with acidic soil

In the garden compost heap, with all the other vegetable matter that you toss in, the effect of coffee grounds is insignificant (unless you are going to Starbucks and taking home a bag of their used coffee grounds once a week). You can counter the acidity in the compost pile by adding a couple bags of manure, an alkaline - a good practice anyway.

Daisy

Name: tarev
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tarev
Jan 31, 2016 10:33 PM CST
Hello D, so far I have used coffee grounds to some container plants outdoors, more to help fight slugs and snails..I heard they don't like it. So far, cannot truly say it was effective but I did notice not much attack happened on my amaryllis after giving some. I also gave some to my calamondin tree, seems not to bother it, but I notice a real good production of fruits this time. I gave some to my china doll tree and for the first time it did not lose leaves this winter..but cannot really attribute it solely on that, we have more rains this time.

The rest of my coffee grounds I have put in my compost pile.

The only plant I have in your list are the jade plants. I don't put coffee grounds on my jade plants or any of the succulents that I have.
Name: D
London, UK
didacus
Feb 1, 2016 2:50 AM CST
Thank you for the reply. I was aware of the acidity and the fact that too much coffee grounds might create fungal problems. I will try the once a week recommendation and see what happens.

Can I add manure and coffee grounds straight to the pots or do I need to wait? :-D I definitely need a small composter as I live in a tiny apartment and the only space I have is the balcony. Any recommendation? I am a bit unfamiliar with the process and equipment needed.

:-D
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ssgardener
Feb 1, 2016 8:14 AM CST
Actually, coffee grounds are not all that acidic! The acidity is in the coffee that you drink, but used coffee grounds are only slightly acidic to nearly neutral. It's certainly not enough to change the acidity of the surrounding soil.

D, there are a couple of different methods of composting indoors or on your balcony. If you're not squeamish, you could start a worm bin. Another method is called bokashi, a Japanese anaerobic composting method that ferments the organic matter (without odor). But this requires you to bury the fermented product to finish the composting process, so you'd need access to a yard or a large container of soil on your balcony.
Name: Elaine
South Sarasota, Florida (Zone 9b)
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dyzzypyxxy
Feb 1, 2016 9:04 AM CST
Here's a link to some directions on how to make a simple composter out of a garbage can, D.

http://www.uaex.edu/publications/PDF/FSA-6029.pdf

I think you could make it any size, and the key to good, quick composting without any smell or mess is to stir it up often, to keep it decomposing aerobically (with lots of air in the mix). If you let it sit too long, anaerobic decomp starts up and it will ferment and stink! You'll need to take a bag out with you for a while and find a source for some dry leaves, or grass clippings would work, too. Know anyone with a yard? Air, and a good mix of materials is the key.

If you don't want to go this route, then the worm bin is the next best thing. Worm castings would be an awesome additive for your potted plants.
Elaine

"Success is stumbling from failure to failure with no loss of enthusiasm." โ€“Winston Churchill
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critterologist
Feb 2, 2016 9:57 PM CST
When it's too cold/rainy to go out to the garden with my coffee grounds or even to toss them off the edge of the deck, I'll empty them into indoor potted plants. I haven't tried it with succulents, but anything else seems like fair game. I usually add it like a mulch in larger containers. I have not noticed any issues with either fungal infections or insect pests -- on the contrary, coffee grounds seem to discourage fungus gnats.
I'm learning to dance in the rain. Thank you, Sally & Chris.
Name: Tiffany
Opp, AL (Zone 8b)
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purpleinopp
Feb 4, 2016 8:48 AM CST
Trying to provide fertility via soil for a potted plant is impractical because the small, closed environment can't sustain the microbes necessary to convert/process organic material into a form that plants can use. Also too easy to accidentally radically alter the PH, or create other wild imbalances that could make plants ill. Making a compost tea with which to water is much more likely to do wonderfully good things for potted plants.

If you're interested in and able to repot a couple times per year, depending on conditions, fertility-via-soil could show decent results, assuming the particular plant liked the particular mix. But becoming too wet, dry, hot, cold, just once could kill the microbes.

I usually don't even compost the materials first to do a compost tea, just put them in my water bucket (at least overnight,) use the water for thirsty potted plants, then dump the contents on the ground in a bed where they can decompose and become part of the mulch. (Before I gave up on pile composting, the contents would have been dumped on the compost pile at that point.)

Anyone even remotely interested in having "good dirt" for plants should enjoy this short lecture, (though it doesn't discuss potted plants at all):
http://permaculturenews.org/2013/09/20/soil-not-dirt-dr-elai...

Edited to say, forgot to say before, KUDOS to anyone trying to compost in an apartment!
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[Last edited by purpleinopp - Feb 4, 2016 4:21 PM (+)]
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Name: D
London, UK
didacus
Feb 5, 2016 1:02 PM CST
Sorry my ignorance. What's a compost tea?
Name: Tiffany
Opp, AL (Zone 8b)
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purpleinopp
Feb 5, 2016 1:27 PM CST
Nothing to apologize for at all, just a thing you don't yet know. Happy to share some info, especially since my previous remarks are surely beyond cryptic without that knowledge.

A compost tea can be anything from steeping/soaking actual finished compost in water with which you intend to water thirsty plants, to steeping/soaking a single item, like coffee grounds, corn cobs, pulled weeds (one of my favs, makes that more worthwhile and important!), or whatever you have available.

This reminds me about "banana water" too. Pureรฉ whole bananas or the peels, dilute into plant-watering water. I usually only do that outside since I don't strain out the pureรฉd bits, and never measure anything, just try to dilute enough to give some to each of my pots. Banana water has done more "wow" things for my plants than any fertilizer I've tried.

I prefer these kinds of things because I've killed plants before by getting carried away into unbridled enthusiasm and lazy measuring with fabricated, packaged fertilizers. If a little is good, more would be great, right? Wrong.

Have you investigated vermicomposting? I've seen many anecdotes about that working well for those without somewhere to compost outside.
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โ˜•๐Ÿ‘“ The only way to succeed is to try.
Name: Rick Corey
Everett WA 98204 (Zone 8a)
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RickCorey
Feb 5, 2016 2:02 PM CST
Many (or at least some) compost tea fans emphasize that the tea should stay aerated as it ages. That encourages aerobic microbes to multiply, and those are the beneficial ones.

Compost tea carries very few mineral nutrients, it is too dilute. But it's the beneficial microbes that are are the main gold in compost tea.

I saw a YouTube video after my own heart, where a fan of Rube Goldberg set up a little air pump and some aquarium "bubble stones" in a 5-gallon bucket for 'extra oxygen'! I wonder if he played music for them, too?

Others just leave the bucket in the shade (cool water absorbs more oxygen, faster, than hot water, and warm microbes metabolize faster than cold ones).

And stir it each time they walk by.

And maybe don't fill a deep bucket all the way to the top. Shallow water has more surface area per gallon than deep water, and oxygen is absorbed through the surface of the water.

Some people even use tea (finished compost, steeped and aged in aerobic water) as a foliar spray to increase the population of beneficial microbes on the leaf surfaces, to DIScourage disease microbes like rust or mildew. I don't know whether it WORKS for all plants and all gardens, but I like they way they think.

Hey! Maybe adding just a LITTLE hydrogen peroxide to steeping tea would supply more oxygen without disinfecting the compost!

[Last edited by RickCorey - Feb 8, 2016 12:07 PM (+)]
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Name: Tiffany
Opp, AL (Zone 8b)
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purpleinopp
Feb 6, 2016 7:20 AM CST
I like that kind of thinking too.

The water used to boil veggies (after it cools) can be awesome for watering plants too.
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Name: Ken Ramsey
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drdawg
Feb 6, 2016 7:25 AM CST
I just dump all my coffee grounds into my potting mix that is "constructed" in my oversized wheelbarrow. It is basically neutral and thus won't alter the pH of the mix. It breaks down over time, supplying a bit of organic nutrients/fertilizer along the way. I still do toss it over my azaleas in the spring and then again in late summer.
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Name: D
London, UK
didacus
Feb 8, 2016 12:06 PM CST
Thank you for all the explanation. I will see what is the best option for composting here on my tiny little flat.

A development on the coffee grounds. For some reason fungus has appeared in all the pots I added it Crying Last weekend I took out what I could from the surface and added a bit of ground cinnamon (as I read that is a good natural fungicide). I will also leave the soil to dry a bit. Any other recommendation?


Name: Rick Corey
Everett WA 98204 (Zone 8a)
Sunset Zone 5. Koppen Csb. Eco 2f
I helped beta test the first seed swap Plant and/or Seed Trader Seed Starter Region: Pacific Northwest Photo Contest Winner: 2014 Vegetable Grower
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RickCorey
Feb 8, 2016 1:24 PM CST
My theory is that, if you build up visible fungus, the surface is staying too wet. If you think of those coffee grounds as a mulch, they are much too fine. They hold water instead of letting it pass through and drying out.

Coffee grounds are very fine and tend to hold water. If you must use them in pots, I'd suggest a thinner layer of grounds, and mix them with something gritty or chunky, like pine bark shreds in sizes from 1/10" (2.5 mm) to 1/8" up to BB size (0.177" or 4.5 mm).

If the surface dries out quickly after watering, you may have less fungus.

But the main problem is that organic additions to soil work better in the ground than in containers. If you're thinking of the coffee grounds as spot-composting or sheet-composting, it would work better outdoors on the soil or in a compost heap. The ground, outdoors, can support diverse life that will compost things like coffee grounds.

Maybe top-dressing each pot with a little finished compost would meet your goals? Or aerobic compost tea?

Organic additions mainly benefit soil as they decompose, and pots usually are not big enough to maintain a soil ecosystem or a compost-heap-ecosystem.

That fungus comes from the grounds "trying to decompose", but instead of being inside a compost heap with an entire "community" of microorganisms, worms, insects etc. working together, it's on the surface of a small pot and just one kind of fungus took over.

Small pots just aren't "the Earth". Trying to spot-compost in a small pot is going to be difficult.

Many or most people rely on a soilless mix in pots to maintain drainage and aeration, then supply nutrients with either soluble fertilizer or something like liquid seaweed. Maybe if you use big pots and replace the soil every year with fresh soil, you could do more in-pot composting.

Name: Critter (Jill)
MD (Zone 6b)
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critterologist
Feb 8, 2016 9:02 PM CST
don't worry about the greenish mold, just stir up the pile of grounds so it dries out... indoors, coffee grounds are more like mulch than like a soil amendment. I have a lot of plants inside in the winter, and probably half makes it outside, so no one plant ends up getting a thick layer, maybe 1/4 inch.
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