The reason coffee grounds are good for the soil is because they are a great source of nitrogen. But you do have to be careful that you don't get too much, so instead of using directly in your soil, put the coffee grounds into your compost instead. This will keep it from overwhelming your plants with nitrogen. The way you can tell if your plants are getting too much nitrogen is if you have a lot of leaf growth on the plant, but the plant doesn't seem to be very strong. A weak plant will be more susceptible to diseases and insects. If you are growing edible plants, the excess nitrogen will cause the plants to taste differently due to the plants' intake of sugar and vitamins being affected.
Now, this doesn't mean that your coffee can never be used on plants directly, you just have to be careful with it. You can use coffee as a mulch for fast growing vegetables, and even the coffee filters can be used in the mulch.
If you have flowers that the slugs like to eat, you can sprinkle coffee grounds around those plants, slugs avoid coffee it is believed that coffee grounds are poisonous to slugs.
Coffee grounds can act as a great natural insecticide on tomato plants. Make your coffee double strength. Let your coffee cool down to room temperature before spraying on your tomato plants. You can even pour the coffee grounds on the leaves and fruit of the tomatoes.
How do you use coffee grounds in your garden?
