Use Diluted Coffee to Fertilize Plants

By: Colleen Vanderlinden, Planet Green  | 

 A weak solution of coffee, as shown on the left, is perfect.
A weak solution of coffee, as shown on the left, is perfect.
Colleen Vanderlinden

You know that last bit of coffee that always seems to be left in the carafe? Don't just pour it down the drain -- you can use it to fertilize your container-grown plants. Coffee grounds (and brewed coffee) are a source of nitrogen for plants, which is the nutrient that produces healthy green growth and strong stems. Coffee also contains calcium and magnesium -- both of which are beneficial to plant health.

To use coffee as a plant fertilizer, you'll need to dilute it. It should look like weak tea -- see the photo for an example. If you aim for about 1/4 coffee and 3/4 water in your mixture (depending on how strongly you brew your coffee), that's about right, but you don't have to be fussy about it. You can use coffee fertilizer on your potted plants, houseplants, or in your vegetable garden. Coffee and coffee grounds can be acidic, but since we're diluting it so much, that's not really a problem unless you're watering the same plant with it every day.

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A good rule of thumb is to feed and water your plants once a week with a weak coffee solution. They'll appreciate the additional nutrients, as well as the water.

Originally Published: Jan 11, 2012

Coffee Ground For Plants FAQ

Are coffee grounds good for roses?
Roses are delicate flowers that need fertilizer every now and then. You can use coffee grounds as fertilizer for your roses, but use them in moderation as they can burn the flowers if used in excess coffee grounds due to the high nitrogen content.
Which plants like used coffee grounds?
Since coffee grounds have a high acidity level, they only improve the growing conditions of a few plants, including blueberries and hollies.
Which plants do not like coffee grounds?
Chinese mustard, Italian ryegrass, asparagus fern and geranium are just some examples of plants that don’t like coffee grounds and aren’t able to grow in soil that contains them.
How do you use coffee grounds on plants?
It is advised that coffee grounds are sprinkled thinly into the soil, at least a few inches from the plant’s stem to avoid damaging them.

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