Coffee Grounds in the Garden

We have many questions about the using of Coffee grounds in compost in the garden in general and as a slug and snail repellent.

In the garden coffee grounds are rich in nitrogen and with a fairly neutral ph can be an OK addition to compost. However do they do what they are said to do?

We have found that they are really of no great benefit, and they are certainly not any miracle maker. Coffee grounds contain caffeine, and this in itself is not much good for promoting new plant growth or improving soil microbial activity.

So if you must get with the latest trend, here are a few ways to use coffee grounds without doing to much damage. Ideally you would use a lot of coffee grounds and these can be collected from cafes, however if you have a home espresso machine just use what you can. And of course you can also use filtered coffee ground, filter and all.

What Coffee Grounds are said to be good for.

  • Try layering fallen leaves, coffee grounds and grass clippings, the leaves are the source of carbon that help balance the nitrogen in the fresh grass clippings and the coffee grounds.
  • Coffee grounds in worm farms
    Try adding some to the worm farm, worms love coffee grounds, but remember worms need a balanced diet so do not over do it.
  • As a snail and slug repellent / killer
    How about coffee grounds to get rid of snails and slugs ? Well its the caffeine that kills the snails and slugs and most of this has been extracted, so probably not the best method. They may not like crawling over the ground.
  • As Mulch
    Use Coffee grounds as mulch, well you could but it takes a while for the coffee grounds to break down, and they MAY inhibit plant growth, they are probably more useful in the compost bin or worm farm

It is also thought that coffee grounds help increase the temperature in compost heaps, helping to speed up the process. So technically what do coffee grounds add to the compost and therefore the soil, well how about a little phosphorus, potassium, magnesium and copper. And around 2% nitrogen. Plus caffeine.

What about for Acid Loving plants?

Azaleas, Camellias Gardenias, Hydrangeas, Hibiscus, Roses, Pieris, Hydrangeas Rhododendrons, and Blueberries are acid loving plants, however used coffee grounds have a fairly neutral ph, so maybe not worth it. However, some gardeners report good results so if you wish to give it a try do so, but record and monitor results, and do not overdo it, over application of any soil amendment can have negative results.

Do you have a story?

If you have tried coffee grounds for any purpose in the garden, let us know, we are always interested in our readers trials, successful or not.

Further Information

We suggest that you are careful in the use of coffee grounds, monitor the results and do not over use coffee grounds. If in doubt, consult your local nursery or a qualified horticulturist for advice.