Spent coffee grounds, the unappealing dark brown sludge at the bottom of your coffee maker after you’ve poured your cup, don’t need to go to waste. Here are a number of beneficial uses for coffee grounds in your garden.

Recycling grounds

Recycling your used coffee grounds on your plot rather than throwing them in the dustbin means you’re generating less waste – even if only a tiny amount. For used grounds are a valuable resource. They contain minerals and nutrients beneficial to many plants, and other properties that can enhance your garden.

As a soil enhancer, acidifier, and natural fertilizer coffee grounds can be added to both open ground and potting soil, as well as compost heaps, and even in worm bins.

Slow release NPK fertiliser

For a start, coffee grounds contain remarkable amounts of nitrogen, phosphorus, potassium (the vital NPK combination). They also contain calcium and other trace elements essential to healthy plant life.

Thus, spreading a thin layer of coffee grounds on beds before digging them in has the same effect, in an ecologically sensitive way, of adding fertilizer to your soil.

Because they are the product of hard, baked dry beans coffee grounds take time to decompose, and to release their nutrients into the soil like a slow-release fertiliser.


Because they are organic coffee grounds also act in the same way as adding humus, or in digging in mulch. The organic particles of ground up beans will help to break up heavy soils. The soil will therefore retain moisture and allow for better air flow through the soil. This makes it easier for root structures to develop and do their job.

Or, simply spread them on the surface in a layer. Thus, coffee grounds act as a mulch, helping to retain moisture in the soil and inhibiting weed sprouting.

Earthworms and worm bins

Earthworms are attracted to coffee grounds. Soil that has been enhanced by the addition of grounds will with time have a higher earthworm population, with all the benefits that earthworms bring to healthy soil themselves.

If you have a vermiculture setup your worms will relish the grounds as a food source.


Coffee grounds are, however, markedly acidic. Care should be taken to avoid packing them round the stems of seedlings, where their presence in quantity can promote rotting and mould.

But their acidic property can be utilised itself. Plants that thrive best in acid soil, that is soil with a low pH, will welcome the addition of coffee grounds.

Such plants are all the berries (strawberry, raspberry, blueberry etc), azaleas and rhododendrons.

And hydrangeas treated with coffee grounds will reward one with large pink blooms, rather than blue.

Roses, too, will benefit from the nutrients contained in spread coffee grounds.

Conversely, avoid adding coffee grounds to soil planted to alkaline-preferring species such as tomatoes, cabbage and parsley.

Rooting stimulant

If you like to propagate plants from cuttings you can use wet coffee grounds as a rooting stimulant. Simply dip the end of your cutting into the grounds in the same way that you would in a proprietary rooting powder, and plant it. The caffeine in the grounds acts on the stem in the same way as it does in your body – as a stimulant.

Pest repellant

Coffee grounds will help to keep slugs and snails away from your plants. The caffeine in the grounds and their high acidity impair the slugs’ and snails’ senses. This deters them from contact, therefore keeping them away.

In the same way, coffee grounds act as a weed deterrent. They will also deter flying insects such as wasps and bees. If you are sensitive to stings from these then coffee grounds are a good natural repellant. However, if you are attempting to encourage bees into your garden, rather find other uses for your coffee grounds.

Natural fungicide

Coffee grounds contain chemicals that have antifungal properties. Mixing coffee grounds with water and using this as a leaf and stem spray can help prevent fungi from attacking susceptible plants.

Compost enhancer

Being high in nitrogen, and organic as well, coffee grounds mixed in with your other kitchen scraps will enhance your compost making efforts in a number of ways. Most notable of these is helping to balance the carbon-to-nitrogen ratio in the material. This is important in encouraging a vigorous composting process.

Moderation and common-sense

But as with everything in life, moderation and common sense should prevail.  In a normal domestic household that consumes a couple of cups of coffee daily per member it is unlikely that you will produce enough grounds to overdo things. But applying all your coffee grounds on your plot every day in one way only may, indeed, lead to an unhealthy build-up of acidity or other coffee ground-related issues.

Moreover, although rich in certain nutrients, coffee grounds lack others, so their use as a fertilizer should be balanced out with the use of other organic fertilizers and soil enhancers.

Suggestion for using coffee grounds on your plot

The best way to use coffee grounds, therefore, is to identify particular uses from the list above that could be beneficial in your particular garden. Then apply the grounds accordingly, monitoring the changes in the subject plants, the compost or your worm bin as you go.

If you notice an undesirable change developing, simply stop. You can always resume application at a later stage. And there is always you compost heap that, on a smallholding, will never contain too many coffee grounds.

To read other articles about growing vegetables and crops click here.

Main image: Coffee beans and ground coffee, courtesy Wikimedia Commons



Leave a Reply

Your email address will not be published. Required fields are marked *