Kraut und Rüben August 2026: Coffee grounds are often recommended as a good remedy for acid-loving plants such as blueberries. We used to do this as well, because this advice was in line with the general understanding at the time. Recent studies show that coffee grounds do not have an acidic effect, because the acids in coffee are almost completely transferred to the coffee during the early stages of brewing. If you want to use coffee grounds in the garden, it’s better to mix them into the compost. There, they contribute nitrogen, among other things, during the decomposition process. When applied undiluted, the polyphenols they contain could inhibit growth.