I was told to add coffee grounds to my blueberries. After I did the leaves on two of them turned dark red and they all fell off. Leaves have returned and loads of flowers, but the berries seem to not be developing well. It is also about a month after my berries should have been picked. I am in Largo Fl. Is this due to coffee grounds and why?

  • I have no clue about the blueberries, because I'm new to them this year, but I can tell you that they recommend fertilizing Nepenthes with coffee, because it helps acidify the potting media and add trace nutrients. I'd assume it's doing the same thing for the blueberries on a larger scale as they like acidic soil.
    – Dalton
    Mar 22, 2016 at 19:28
  • I had the same issue although I did not put coffee grounds. My leaves turned dark red and fell off and eventually the plant died.
    – JStorage
    Mar 22, 2016 at 20:54
  • What season did you apply the coffee grounds, and does your plant normally drop leaves once a year? Mar 23, 2016 at 18:32
  • Did you also test the soil pH before doing this? Mar 23, 2016 at 18:33
  • Blueberries need boat loads of water to thrive, the soil need to drain well because they don't like to sit in water, but they do need to be watered a lot and often. I am not telling you to water them some more, but are you aware of this and having you watering them enough? Under watered blueberries bushes will turn red.
    – Escoce
    Mar 30, 2016 at 14:09

2 Answers 2


Reddening of the leaves of blueberry plants can be caused by a lack of phosphorus. Although coffee grounds contain phosphorus, they are also highly acidic. If your blueberry plant were already in acidic soil as it should have been, you could have made it even more acidic rendering phosphorus insoluble and unavailable to the roots.

Nitrogen (N), Potassium (K), and Sulfer (S) are major plant nutrients that appear to be less affected directly by soil pH than many others, but still are to some extent. Phosphorus (P), however, is directly affected. At alkaline pH values, greater than pH 7.5 for example, phosphate ions tend to react quickly with calcium (Ca) and magnesium (Mg) to form less soluble compounds. At acidic pH values, phosphate ions react with aluminum (Al) and iron (Fe) to again form less soluble compounds.


That's why it is suggested that if you're adding a lot of coffee grounds to your compost pile, you also add some agricultural lime.


One teaspoon of sulfate of ammonia to 9lt of water water twice a week.

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