Coffee Grounds as a Planting Medium

February 18, 2003

I have LOTS of coffee grounds. I use them for lawn fertilizer, in compost, for in situ composted beds. I still have lots of grounds. Albert_135 has reported good results withusing coffee grounds as a planting medium, so I decided to do a little experiment.

I made three planting media: commercial potting soil, straight coffee grounds, and a half and half mixture of the two. In one test, I took some marigold seedlings that I had started in a paper egg carton and transplanted them into 4 inch pots containing each of the planting media. In another test, I started seeds of: tomato, kale, broccoli, chard, and lettuce in paper egg cartons, using each of the planting media.

The marigold seedlings in the various planting media showed a similar growth rate. The plants in the coffee grounds had a purple color to the outer (older) leaves. Those planted in commercial potting soil had green leaves, and those planted in 50:50 coffee grounds:potting soil were almost exactly intermediate between the other two.

Of the seeds, only tomatoes showed 100% germination. In every case, the seeds planted in the commercial potting soil germinated first, followed by those in the 50:50 mix, and then by those in the coffee grounds. In the tomatoes, the differences in germination times were within a day. Other plants showed more variation. The broccoli, kale, and lettuce showed little difference in germination success between the potting soil and the 50:50 mix with 91% and 89% of the seeds germinating. Only 61% of the seeds planted in coffee grounds germinated. The chard is slower, but seems to show the same pattern. The seedlings in each of the planting media appear equally healthy as the first true leaves appear.

Not surprisingly, commercial potting soil works better than coffee grounds in supporting seed germination. However, mixing this half and half with coffee grounds has little effect on the germination rate. Tomatoes germinate as well in coffee grounds as in potting soil.

Comments (58)

  • Chris_MI

    Thanks for the popular idea. My naked yard needs alot-even popular trees would be better than nothing-and free too. I'm going out after I get dressed and trim my one tree.

  • albert_135   39.17°N 119.76°W 4695ft.

    Poplar cuttings mentioned above now have leaves but the parent tree does not have leaves yet. The cuttings in their jar of coffee grounds were outside near the parent tree so that temperatures would be about the same so there is something here yet to be explained.

  • jschyun

    The first post mentioned that in the pots where the plants were growing in all coffee grounds, there was a purplish color to the older leaves. This sounds like phosphorus deficiency, which can be corrected with a little rock phosphate.

    You can actually buy coffee grounds if you have money to waste. (Copy and paste the following link into your browser's address bar)

    Also, I thought you might be interested in this:
    Posted by: lil_Rhody z6b RI (My Page) on Sun, Dec 29, 02 at 8:28

    WOW! after a little effort in research I found this:
    "Caffeine is present in coffee and cocoa beans to protect the plant against harmful insects, but it is pure chance that it has a toxic effect on molluscs (slugs). Researchers say that they do not know why caffeine killed the slugs. But they suggest it may act as a neurotoxin, since exposed slugs fell to "uncoordinated writhing" before dying. It could be very useful because coffee is not likely to harm people so it's far better than spreading the traditional products, which also harms beneficial insects."

    Source: New Scientists
    Journal reference: Nature (vol 417 p 915)

    "After you brew your coffee, save your grounds. Put them in a canister like an ice cream bucket or coffee can. Scratch them into the soil. Coffee grounds are an excellent fertile source of organic matter of plant food. They contain about 4% nitrogen, 1% phosphorus, and 3% potassium. You can also dilute your coffee grounds with water. This makes an excellent liquid fertilizer that's completely organic. Keep in mind, coffee grounds are acidic, so you want to be careful how much you apply to the soil."

    Source: Rebecca's Garden

    I disagree with the statement that coffee grounds are acidic, but otherwise, I thought the passage was useful.

  • jschyun

    Here's a link on Starbuck's website that has an analysis of the nutrients in the spent coffee grounds.

  • Scott Wallace

    Not to sound stupid, but once you put the cuttings or seeds in the grounds I'm assuming you water it just like you would any other propagation medium?

  • albert_135   39.17°N 119.76°W 4695ft.

    Cannot find my post about cottonwood seedling in coffee grounds. Took two seedlings that had germinated in the gutter and put one in coffee grounds and one in soil. Last year the one in coffee grounds grew four feet and the one in soil grew two feet. This year the one in coffee grounds had leaves a good week before the one in soil. The trunk of the seedling in coffee grounds is larger than the one in soil but NOT as strong as the trunk of the shorter tree in soil.

  • sqh1

    Starbucks company policy is to give away free gounds to anyone who asks for them to use for gardening.Go to their site and check them out.

  • henry_kuska

    I have an outside screened (top and bottom) wooden "box" in which I germinate rose seeds. The screening is necessary to prevent "critters" from eating the seeds. I had a problem with slugs eating the young seedlings until I added coffee grounds to the soil.

  • hostacrazy

    Does anyone know how much used coffee grounds can you add to your compost pile without hurting it? My husband and I drink about 4 pots a day. So, far I have been adding it all in but then started wondering if I was doing more harm than good?

  • TxWill

    Hostacrazy- You may want to ask that question in the soil forum. As I recall, I don't think you want to have more than 20% of your total compost as coffee grounds.
    I don't think a single family could generate too much grounds to be composted. I've been grabing as much from Starbucks as I can find (at least 5lbs/week) and I have never had a problem.

  • albert_135   39.17°N 119.76°W 4695ft.

    My original thread must have aged off. So I will try to recreate it and try to keep it here on /lab/ forum.

    1982-1994 Had a Sanseveria (? S. kerkii) in an office cubicle that was "watered" with nothing but black coffee, about thirteen years.

    c.1992-1994 Transplanted tall single flowered marigolds into a planter of coffee grounds; were more red-orange than the same in soil.

    1997 Planted a rooted Ficus benjamina cutting in nothing but coffee grounds as a planting medium. It is still thriving.

    1998 Did the Bougainvillea mentioned above in this thread. It is still doing alright as far as I know.

    2000-2003 Transplanted annuals into pots with coffee grounds as a planting medium; snapdragons, Martha Washington [whatever] and an unknown with tiny white flowers. They all thrived.

    During this period I did the cottonwood seedlings. The one in coffee grew faster and larger, the control in soil grew slower and stronger.

    Midwinter rooting of hybrid poplar cuttings in coffee grounds was a success.

    Starting annual seed in coffee grounds has not been successful to date.

    Attempts to root common veining houseplants that will root in water, a pathos(?) and the one with the purple and silver leaves have not been successful; but the latter will live in dilute coffee once rooted.

    I am currently growing an Iris in coffee grounds.

    Note: in each case above the coffee grounds had been accumulating in a container under the sink for months i.e. none or fresh. I wonder if that matters.

  • DrynDusty

    Interesting thread. How do you keep the grounds from getting moldy before you are ready for use? I get all sorts of beautiful, orange molds with luxurious fur coats.

  • lizzylu

    I have a few jars of instant coffee we don't use anymore. Can instant coffee be used the same as regular coffee?

  • deusse

    won't the high nitrogen level make more leaves than fruit on a tomato?

  • albert_135   39.17°N 119.76°W 4695ft.


    All experiments reported on April first (That was no joke. I just noticed the date. Reports above are for real.) Repeat. All experiments reported on April first above were done with old, coarse WalMart grounds. Some grounds were two years old. The freshest grounds must have been at least a month old.

    Anyway, I tell you all this to report a new experiment. Three plants in fresh Starbucks expresso grounds failed to thrive. Next report will probably be several months.

  • albert_135   39.17°N 119.76°W 4695ft.

    The plants in fresh Starbucks expresso grounds that failed to thrive (See Aug report above.) were suffering from too much something. I suspected too much water. You see, expresso grounds in a well drained pot just flow out the holes in the bottem when watered so drainage must be restricted.

    The excresso grounds form a hard crust around a bundle of "mud" in the middle of the pot. I just broke open one that had been setting in the sun on a deck since August and it still had mud in the middle.

    My conclusion, expresso grounds must be treated differently in experiments to use them as a planting medium.

  • Marlene2

    I would like to know how you keep your grounds from going mouldy. If I keep them over the winter, how do I store them.

  • albert_135   39.17°N 119.76°W 4695ft.

    I have never seen the moulds that people talk about. I live in the high desert, humidity today is about 24, and I store grounds in an open container. I would really like to see the orange mould people talk about. Mycology was a favorite class of mine and still find moulds fascinating.

    Is there a problem with mould on coffee grounds other than people seem to abhor moulds except in blue cheese?

  • baci

    albert_135, I wonder if you are having greater success because you are a high desert grower. I have seen the mold also, when I over water my grounds or stick it in a sealed container. The grounds seem to liquefy & smell if kept too moist. The grounds seem to do better if they are kept somewhat dry & have plants in it that can tolerate it.
    I am also doing coffee ground experiments. My tomatoes did germinate, but the seedlings damped off. I planted monkey grass in coffee, but it seemed to discolor soon after planting. I tried sprouting theobroma cocoa in it but the seeds molded. The one thing that I have had success with is chicory coffee root  it seems to be taking off & doing well. I have not added any fertilizer/nutrient yet  I am just trying to see if the plants will take.
    I am going to try some of your plants as I think this is a great idea.

  • albert_135   39.17°N 119.76°W 4695ft.

    The bougainvillea died, perhaps from neglect while the owner was on vacation. There is no reason to believe the coffee grounds did or did not have anything to do with the demise of a six year old plant.

  • Rhannie

    As I live in a very humid area, and mould starts to grow within 24-48 hours here, I usually dry my coffee grounds before putting them in an open container. If you spread them out on a flat surface (I use the styrofoam trays meat is packaged on) then leave them in a sunny well area they will usually dry out pretty quickly.

  • watermanjeff

    Here's a link that gives a lot of information including the PH of spent coffee grounds.

    Here is a link that might be useful: faq on coffee grounds

  • fledglingardening

    Sharon_9--Out of curiosity, did you use a potting mix that had plant food already in it for your experiment?
    Also, has anyone thought of trying a mix of coffee grounds and something inert to add air, like perlite? Just a thought. After reading all this I may have to start saving my used tea leaves etc for my plants.

  • brideyl_b_yahoo_com_au

    I have had big problems with a bunch of seedlings recently - the lower leaves went purple and began to curl. I had been feeding them liquid seaweed and coffee grounds. I went to the trouble to look up many sites to find out what was wrong with them and I believe it is what is known as "Manganese toxicity" and related to "acidity complex". This site has lots of photos of deficiencies and toxicities in tomato plants:

    I have limed and flushed plenty of clean water through to fix the problem. I had been feeding them liquid seaweed and coffee grounds, both of which can have a high level of manganese (see:, and coupled with a low pH can result in purple lower leaves, particularly along the veins. These plants have subsequently fruited profusely so I'm thinking lack of phosphorus is not a problem!

    So If you're using coffee grounds, make sure you check the pH of the potting mix or soil and keep it from becoming too acidic, using lime or crushed egg shells (

  • LCSMOM2004_yahoo_com

    If I mix coffee grounds with my compost, is there anything I shouldn't put it on? Can I used this mixture when transplanting a lilac bush?

  • LCSMOM2004_yahoo_com

    Some people mentioned using tea this in addition to using coffee grounds or instead of using them?

  • albert_135   39.17°N 119.76°W 4695ft.

    The Ficus planted in coffee grounds in 1997 reported above is still alive and thriving. It is in low light with very little water.

    Gena, people who mention tea bags usually don't give much additional information. Were I to get a gallon of tea bags I might try another Ficus cutting in just tea bags. I would expect it to grow and thrive if not given too much attention.

  • gardengrub

    Coffee grounds seem to have helped hydrangeas which have lived in pots on my deck for about 4 years! They must be survivors OR love coffee grounds - I don't know much about them. They always end up drying out and having to be revived poor things and yet they are ready to bloom again wow! I've also given them crushed egg shells which I save on my counter in a tall container and crush with a potato masher when they dry a bit.

  • rags75

    Just a simple dumb question, can I use coffee grounds on any plant fruit tree fruit bush or just plain flowers???? Also I don't drink coffee can I use fresh coffee around all my plants to help with the growing process, from what I have read people only use it around roses, I hope to hear from someone RAGS

  • albert_135   39.17°N 119.76°W 4695ft.

    I'm confused "can I use coffee grounds on any plant .... Also I don't drink coffee..."

    Use it if you got it - cautiously. Be careful and watch what happen and there will be no problem.

    Coffee is and expensive way to get benefits unless you have to deal with waste or you are into helping Starbucks deal with their waste. Don't spend money on coffee hoping to help your plants somehow.

  • harrywiles

    Hi there,
    I've just read through all the above post and find it fascinating. I work for a tiny independant coffee stall in the uk and we are really keen on cutting our waste and pollution as much as we can (everyone bikes to work, we have blankets instead of patio heaters etc etc.
    I really like the idea of being able to fill up our customers disposable cups with spent coffee and giving them some free seeds so they can take the cup home and grow a plant in it...

    I was wondering if anyone can recommend a plant that might be well suited to growing off pure coffee and in the dodgey English spring-summer time!

    many thanks!

  • ilazria

    I know this is an old post, but it came up while I was searching on using coffee grounds as rooting medium. Has anyone done anything more with this?

    I'm messing around with different frugal/homemade rooting ideas, and trying to come up with the best "blend." (see link to my post in the propagation forum) My gardening budget is very limited, so I'm trying to find things that I would commonly find around the house or free for the taking to encourage root growth. I would think the trick with using coffee grounds would be how to balance the acidity. An acid loving plant like roses or blueberries might respond favorably to straight grounds, while plants that lean more towards alkaline soil would be less successful. So what would be a good frugal item to counter the coffee's acidity without being toxic to the plants?

    I'm not getting much response in the propagation forum, so I thought I would get some feedback here.

    Here is a link that might be useful: using alcohol to extract willow rooting hormone

  • daislander

    used coffee grounds which most people think would be acidic actually are pretty ph nurtural.

  • somegeek

    Agreed - unroasted green coffee beans are acidic. The roasting process lowers the actidity of the bean. These espresso grounds are typically from dark roasted beans which contain the least amount of acid when compared to a ligther roasted bean.

  • angelady777 (Angela) - Zone 6

    I just recently read that fresh (less than a month old) coffee grounds are still too acidic to start most seeds in. They get less and less acidic over time. (An article from Washington State University's Horticultural Department with great information is sited below my signature that also insinuates that they lose acidity gradually over time. They apparently also suppress many plant diseases and problems.) Composted coffee grounds have been known to test at neutral after a year of composting them, not straight after being used in a coffee maker. It appears that they are mildly acidic after a minimum of a month of composting them. Most plants will thrive in these conditions.

    I tested recently myself with 1/3 mix of spent coffee grounds that were fresh, 1/3 compost, 1/3 fine particle soil as a seed starting medium. Now, I do pre-sprout my seeds in a wet paper towel in a baggy first, so keep that in mind. Several different seed varieties have come up and done well, but it does appear it's not as good of germination as when I didn't put coffee grounds in the seed starting mix. I think I'll try putting the spent grounds up for a month in the future before trying to using them immediately. I'd prefer them to be less acidic before planting something being straight into them while they're still fresh. My soil here is alkaline, the compost is (I'm presuming) near neutral, and the coffee grounds are acidic being used fresh, so that might be why I still had pretty good germination. I'll either add wood ash to the mix or wait a month to use the grounds next time, though. I just hate to loose any seedlings at all, especially on my heirloom veggies.

    Overall, though, I'm incredibly happy being able to utilize coffee grounds, not just in my compost bin, but also directly into a soil mix. Even if I hold the soil mix in the garage for a month before using it, that's not much trouble to go through for cheap seed-starting soil that's healthy for my plants and is basically already fertilized, anti-fungal, and strongly limits plant disease and even some plant pests!


    Here is a link that might be useful: Article by Linda Chalker-Scott

  • loswan

    I do the crest and trough line planting, last year it was so beneficial for the heavy rainy season, this year, leaving the seedlings alone on the crest while coffee grinds nestle in the troughs has proven very beneficial to predators. Either after harvest or beginning spring these coffee grind filled troughs will turnover with manure and topsoil to fertilzie the 2011 garden. Thank you for the valuable topic

  • albert_135   39.17°N 119.76°W 4695ft.

    Some fascinating stuff at Posted by tapla ... on Thu, Aug 19, 10 at 19:01 but none of it is referenced. I will try to track down references. Some things in the linked post might explain why my office plant lived for 13 years on coffee but didn't do much else [Good for an office plant?] until it was moved and transplanted. This could also explain why my ficus planted in coffee grounds in 1997 is not as large as would be expected for a 13 year old ficus. I will try to track down academic references.

  • albert_135   39.17°N 119.76°W 4695ft.

    My latest collection of links found here: Allelopathic, autotoxic Chemicals in Coffee:. I invite you to peruse the links more carefully and report anything I may have missed.

    So far all I have found in these that have been reproduced in controlled experiments is that some products of coffee inhibit the germination of weed seed and that caffeine sprayed on plants will kill baby slugs.

  • Doug_Haiti_gmail_com

    I had a brain storm yesterday. I have been planting mahogany trees from seedlings around my yard in pots and just thought why not cut the tops off the Starbuck's bags and use the coffee and bag as a tree pot. Then one day I will get a piece of land and have a mahogany tree farm. I am glad this forum is here. I will report on how well Cuban mahogany grows in Starbucks coffee bags.

  • KatyaKatya

    At the beginning of this thread, purple coloration in the lower leaves was mentioned when growing in coffee grounds. Now this is a symptom of phosphorus deficiency. I feel it means that coffee grounds with a small amount of added phosphorus are a very good planting medium. I don't know what it could be - bonemeal? Something with a high P in its N - P - K index.

  • boizeau

    My understanding is that coffee grounds are not rich in any one element, save potash. The earthworms love them and so it indirectly will improve garden soil. I add them around my shallow rooted plants like Ribes and Raspberries. I get them for free, so why not? The purple color sounds like phosphate deficiency, and coffee grounds have very little of it.

  • georgeneschreiner

    I have never tried coffee grounds as a planting medium but I do use them on acid loving plants such as rhododendrons and azaleas with good results. As someone in this thread already stated, the earthworms love it and the plants are fine with the acidic nature of the coffee grounds.

    I will try it on my raspberries this year to see how that works.

  • capoman

    I use coffee grounds in compost, and can see using it as an amendment. IMHO as a soil by itself, I think it would be too water retentive. The high nitrogen content would be more suited to leafy vegetables then crops like tomatoes. I do think it's best use though is as a compost amendment. I much prefer pine bark based soils in pots which are cheap and easy to make and known to work very well.

  • albert_135   39.17°N 119.76°W 4695ft.

    I am finally give up on the ficus planted in coffee grounds in 1997 (Reported above in this thread on April 1, 04). I has been alive for 14 years now but has refused to thrive the last several years. Each year in spring and fall it loses leaves as some ficus do but the last two years it has lost almost all its leaves as the season changes and it has not grown much in height for about 5 years now.

  • willylynn

    I'm curious, if you use a paper coffee filter can that be put in with the coffee grounds. I sure hope so because I have been putting the paper with the grounds in my compost.

  • Mari_88


    Yes the coffee filters will break down in a compost pile, especially if you tear them into small pieces, but left whole will work too.

  • quone

    When doing a search for which plants like coffee grounds, I knew I would end up at Gardenweb! I never considered using them as more than compost, but now I'll definitely experiment more. I just replaced my garden soil ( which was 90% silt) with a couple of cubic yards of 70% wood compost/30% soil. The seeds I planted have all come up, but some of the tomatoes are pretty slow so I'll try some grounds to see if they like it. Anything that deters snails and slugs is a bonus, too! We also have a huge pillbug problem, but I'm guessing they'll just laugh at coffee grounds like they do at everything else, but that's another forum...

    Thanks for all the great info!

  • richcoffee7

    hi regarding using spent coffee grounds as a growing medium. I have just done experiments using SCG mixed in with peat at different ratios namely 25%,50%,75% and 100% to grow tomato and geranium seedlings. It was not a success the tomatoes in the 100% were dead within a week and the seedlings in all the other mixes did not thrive.I thought that this was due to the fact that the SCG were to acidic but when i tested the ph of all the mediums it turned out that the higher the % of coffee the more alkaline it was I also had the problem of the leaves going a purple colour in the tomatoes and the geranium leaves went a yellow colour.
    I thought that it might be that the SCG are to high in nutrients which scorches the seedlings or it is a lack of some nutrients causing a deficiency. Two samples have been sent away to a lab for testing just waiting for results otherwise if anyone has any thoughts on why it did not work please advise.
    i would appreciate any information thanks !!!!

  • hummersteve

    The other day I stopped at starbucks and asked them about collecting some coffee grounds. Obviously I wasnt the only one asking for them. Anyway they told me to check in the blue tub out back. Sure enough there was a large bag of grounds. I have used a good bit of it in vermicomposting bin . I then weighed the bag of what was left . There is still 20# left in the bag this will last me a good while.

  • Angel of God

    can a coffee grounds as soil media can affect the taste of the plant (potato). thank you!

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