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Using Coffee Grounds & Banana Peel in the Garden

Most urban readers can get hold of quantities of coffee grounds, the high street coffee shops give them away. This reader has a source for both coffee grounds and, unusually, banana peel in volume. But what’s the best way to use them?

Coffee Grounds

Coffee Grounds – most of the high street coffee shops will give you coffee grounds on request. Even Morrisons and some other supermarkets are now doing the same.

Trevor Owen asked about coffee grounds and banana peel

What are the best uses for coffee grounds and banana skins on the garden or in the greenhouse, I have good reliable sources for both.
Good gardening.

Are coffee grounds as good as claimed for the garden?

Personally I’ve no experience of using coffee grounds in volume. There’s quite a lot on the internet about using coffee grounds that suggest it’s some sort of miracle plant food. You could be forgiven for thinking they’re actually promotions by coffee shop chains to save their waste disposal costs!

However, James Wong isn’t so keen on using coffee grounds. He’s a self-confessed coffee fiend as well as a scientific gardener and did an experiment where he applied it to one bed and compared with an untreated bed. The results were that coffee grounds applied directly and thickly had a negative effect on the soil and plants. Full article on the Guardian here: Gardens: so you think coffee grounds are good for plants

Using Coffee Grounds in Compost

A search across our chat and help gardening forums showed that a number of the members who add sizeable volume coffee grounds as a ‘green’ to their composting were happy with the results. One member interestingly wrote about using them in mushroom growing.

Coffee Grounds for Growing Mushrooms

My wife bought me a mushroom kit for my birthday recently. Reading the blurb and the growing medium is coffee grounds, laced with mycelium. They’re growing like the clappers in the utility room at the moment.

Banana Peel

With banana skins, once again I’ve no personal experience of using them in volume. But once again, the internet has loads of people singing their praises and suggesting all sorts of ways to use them in the garden.

Banana skins are chock full of nutrients, the most relevant to gardening being:

Banana Peel

Most of us have a few banana skins in our compost bin but what about large amounts?

  • Calcium 0.35%
  • Magnesium 0.23%
  • Potassium 5.72%
  • Phosphorus 0.32%

They are also high in sugars, which will promote microbial action in composting.

Banana skins are, of course, an organic material and they’re not particularly acidic so they will easily compost down. As with most materials, they will compost faster if they’re in smaller pieces but that’s not necessary, it just reduces the time to compost. I’d expect a very large quantity just piled up would be reduced and usable in a year or so.

Composting Best Route

The simplest thing I can think to do with both the coffee grounds and banana peel would be to compost them together with any other materials you have to hand. Torn up brown cardboard and paper would go well with them as a brown, even finely shredded wood chips.

You’d need to experiment to find the best ratios and materials to add to speed up the decomposition.

I’ve always felt one of the major benefits of composts is the material mix ensures a wide range of micro-nutrients as well as NPK. If you aren’t able to add a decent amount of other materials to the coffee grounds and banana peel compost, don’t worry too much. Just use the compost thinly around the garden in conjunction with other composts and manures etc.

Which is Best? Coffee Grounds or Banana Peel.

I must admit that, if offered a choice of coffee grounds or banana skins, I’d go for the banana skins. With the proven nutrient levels in banana skins they’re probably much better as a compost material than coffee grounds.

Posted in Allotment Garden Diary
14 comments on “Using Coffee Grounds & Banana Peel in the Garden
  1. Fiona forsyth says:

    I was given some coffee grounds by my local cafe ,I was hoping they would keep the slugs away , in the morning I found lots of the slimy little critters on My courgettes so that was a waste of time but I did find that it kept my cats off my newly dug flower bed they just hated the smell .
    So if u need a good cat deterrent coffee grounds is a winner

  2. Tom Wilkinson says:

    I’ve been using coffee grounds as a cat deterrent now for a couple of years and I find it a most effective method of deterring these blighters from both my flower beds and vegetables. Unfortunately you need to keep re-applying it each time it rains. this is no hardship as they are free anyway.
    Three cheers for coffee shops.

  3. Stephen Jarman says:

    Hi, coffee grinds for rhubarb; works brill, makes the stalks really pink but no coffee taste. Also helps bust up heavy clay soils like mine.

  4. Doug says:

    My only experience with coffee grounds is in growing Blueberry in pots, as I dont have a acid soil

    for 2 years I used Ericaceous compost and the growth was poor and spindly, 18 months ago I added 2 inches of neat coffee grounds to the pots and since then the plants have put on 2ft plus of growth plus good healthy new shoots from the root cluster.

  5. Wendy Smith says:

    I’ve taken into account off all your comments and will be trying them out, I’ve had no experience with either of these yet but as some of our vegetables didn’t grow very well, we need to try some different, I’ve read on here that a lack of calcium is what could have cause my Brussels sprouts to be very short if anyone knows anything I will be ready to read your comments, if anyone would like to add me to there email address then please feel free I’m also on Facebook in the name of Wendy Wilson as I’ve not been married for long, any help on gardening would be very much appreciated especially on soil and how to add vitamins to it and how to keep your compost bin hot ours isn’t doing much at all, it’s not for the want off trying but no matter what we do it just doesn’t seem to do anything thank you

    • John Harrison says:

      Hi Wendy – we don’t make emails public as they’ll get picked up by spammers and so forth. Why not join our chat forum where there are loads of knowledgeable gardeners happy to help.

  6. Hilary Walley says:

    I was reading in “Folk Medicine” by D.C. Jarvis MD, that plants suffering from lack of potassium would stop growing, eventually turn yellow and die. I had such a sickly plant, one of my tomato cuttings I was cloning over winter which had ceased growing for several weeks and its leaves had become hard and dry. So, knowing that banana peel is full of potassium I wondered how I could get the potassium out. I put the peel in a pan of water and left it for two days before using it to water said plant. Wow! within 2 weeks new lush green growth appeared and it survived the winter and thrived allowing me to take several cuttings which I grew on over the summer.

    • Chris C says:

      I see the logic of this, but how many skins did you use and to what sort of ratio did you use. Did you dilute the feed further when feeding the plants.

  7. Mike Broughton says:

    Finding this usefull

  8. Tony Summers says:

    I have read somewhere that coffee grounds can be effective in deterring voles and moles. My lawns have suddenly become a mass of holes and tunnels due to voles. I have so far not seen any success from the coffee grounds. Does anyone have any experience of this or know of a truly effective solution to the voles?

  9. Kezi says:

    Hello, last year I put coffee grounds on my plants, I have a coffee crazy family and needed something to do with the leftover used coffee, I found it worked brilliantly with all my berries and fruit, but not so well on anything else, but it did seem to keep the ants off. My strawberries did especially well, they actually doubled my crop from the year before, they seemed to really like the acidity of the coffee, and it made them a lot more flavourfull too. Every so often I just put a thin layer of coffee over the pots. I now also steep any extra coffee and even old tea bags as well in my water to give it boost and it seems to be doing well.

  10. Jean Markham says:

    First I must thankyou for your interesting tips.I have four grapevines which trail over a pagoda but every year the grapes either get mould or are so small they do not ripen
    Any tips please. I also purchased a hot bin it was very successful last summer but went down hill in winter get get quite a lot of liquid food from it which I feed my greenhouse and raised planters with my husband has also taken some to the allotment. Have you tried these hot bins ?

  11. David SCOTT says:

    I use banana skins for 2 purposes:-
    they ripen green tomatoes if draped alongside the fruit in the greenhouse. Also in a brown paper bag they assist with ripening after picking
    I also feed them ( after cutting into small segments)to my hens – they love them

  12. Pam Ley says:

    I’ve been putting coffee grounds around a hydrangea that was blue when purchased, turned pink when planted despite this area normally having acidic soil. It’s done absolutely NOTHING. The hydrangea is coming out!!!!!!…..it’s had its chance! …..
    I don’t ‘do’ pink….
    Incidentally I have read recently that the coffee grounds need to be fresh ones, not used…..oh well it might have lightened the soil a bit I guess!

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