Coffee Grounds – Passion or Poison?

By Stephen Sykes, Director of Sustainability, East Lancashire Chamber of Commerce

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I discovered the other day that 500,000 tonnes of used coffee grounds are produced in the UK each year and that we drink 95 million cups of coffee a day! I unearthed this in a long overdue catch up with Steve Snape a very interesting chap in in East Lancashire, and the only Worm Farmer that I know.

Steve does not breed worms for bait for anglers but as part of his business ACT for Life ( where he produces worm compost or vermicompost and “Worm Tea”. The last time I spoke to Steve he happened to mention in passing that coffee grounds are an aphrodisiac for worms. By chance I happened to mention the words coffee grounds, worms, aphrodisiac, and golf courses in the same sentence my colleagues at Glasgow Chamber of Commerce asked me to write this piece. I should really learn to keep my mouth shut!

So back to Steve’s allotment in East Lancashire, for those out there unfamiliar with Vermicompost and Worm Tea, the Greek philosopher, Aristotle in his writings “History of Animals” describes the humble worm as “the intestines of the earth”. The worm is an essential soil organism that aids the decomposition of plant litter and the recycling of nutrients, breaking down and conditioning plant remnants in its gut.

Making vermicompost is an art, Steve carefully selects a mixture of food, green and brown (cardboard, paper, etc.,) wastes to rot for his worms. The worms feed on the mould that grows on the rotting mix, and progress through the soil aerating it as they go the resulting worm casts or “worm poo” improves the overall soil structure and provides beneficial nutrients for plant growth.

The worm castings can also be added to rain water (or dechlorinated) , with the water carefully aerated to encourage the growth of microbes, then with the addition of a small amount of sulphur free molasses, itself a waste or by product of sugar refining causes an exponential growth in the microbe population and the resulting Worm Tea can then be applied to plants, crops even grass to increase growth, crop yield and facilitates Building Resilience in Crops (BRiC) which helps with adaptation to climate change.

The use of vermicompost and Worm Tea improves BRiC, by increasing root and plant structure and growth as well as providing thicker skins on fruit etc. making them less penetrable by insects. So, for golf courses and sports fields and pitches the application of these products can result in the increase of root depth aiding the grass to survive longer dry spells as a result of climate change.

Getting back to the title of this piece, Coffee Grounds – Passion or Poison? Passion – Steve told me that when he adds spent coffee grounds to his “food” mix, he noticed that the worms made a bee line for it, that they produced more eggs (three worms to an egg) and the resulting worms were bigger and fatter. The coffee grounds also improve the texture of the soil and vermicompost as well as adding nutrients. Coffee grounds are rich in nitrates, these are then fixed into the soil providing benefit to the plants, crops, grass etc.

Poison? A word of caution, getting the mix and balance right is critical, too much nitrate in the soil can cause “nutrient lock” and stop plants from growing. Equally did you know that caffeine is also a natural pesticide keeping slugs and other pests at bay via caffeine poisoning!

Amazing what you learn down on the allotment, if you would like to know more about vermicompost or Worm Tea, don’t come to me. Get in touch with Steve Snape at ( or