Spent coffee grounds can be used in the garden however they do need to be used properly. We look at range of suggested uses and compare these to our experiences
Myths and Maybes about using Coffee Grounds For Plants.
- Coffee grounds are acidic.
Coffee grounds are actually close to neutral in pH usually around 6.5. So they will not lower the pH of your soil. - Coffee Grounds are high in nitrogen.
Coffee grounds do have a little nitrogen around 2%, and a few other nutrients, however they are not a great fertiliser, they do not contain a lot of nutrients. - Coffee Grounds can be applied directly to the soil.
Partly true, a little can be applied to the soil and mixed through well.
However it is recommend that when using coffee grounds for plants that they are composted with a range of other materials before using in the garden. - Do Coffee Grounds Suppress Weeds?
From anecdotal evidence, yes they do. - Coffee grounds can be toxic to plants
The initial application of coffee grounds can reduce the availability of usable nitrogen when first applied
In large amounts coffee grounds can have a negative effect, in fact they can kill plants if overused.
As well as that, Egg shells can reduce the amount of usable iron when first applied. so again be careful. - Coffee grounds can inhibit seed germination.
This seems to be the case, so no coffee grounds in seed raising mix. - Coffee grounds can deter slugs.
Yes this seems to be true. A 2% solution of coffee grounds and water can deter slugs, and in fact could kill them. The extent of the success of this depends on how much caffeine is left, usually not a lot. We suggest you experiment on a small area…..
Try them on a small area and observe the results on plants as well on the slugs. - Coffee Grounds can deter/kill Mealy Bugs
We have found this to true. We tried this with some Hippeastrum papilio bulbs that were not flowering due to mealy bugs, and it worked wonders.
Our recommendations for the use of Coffee Grounds For Plants and in the garden in general are:
- We strongly suggest that you compost your coffee grounds with other materials such as vegetable waste and lawn clippings before using them in the garden.
- Experiment with them as a slug and snail deterrent if you must.
- Don’t add coffee grounds directly to the soil.