I have a small indoor garden. Unfortunately, I also have a dozen liters of spoiled wine. Intuitively, I think watering edibles with wine will be beneficial for them, as the wine carries already dissolved organic material. However, I am beginning to worry about a possible acidity change in the soil. Maybe also other factors, that I haven't considered exist as well.
Is it a good idea to water edibles with spoiled wine? (bonus question: what about coffee residue?)
Spoiled wine is sometimes converted to vinegar through spoilage. Vinegar is a herbicide. If it's not vinegar and simply "off" tasting, it will still contain between 10-18% alcohol by volume, and alcohol is also a herbicide. So, no, don't put poison on your plants.
When wine goes off, it literally "turns to vinegar". The ethanol becomes ethanoic acid (=acetic acid or vinegar).
Ethanoic acid is relatively "weak" (acidity depends on the concentration, reactivity, and ease that it disassociates the H+ ion - my "weak" refers to the latter two properties).
Although a glass of bad wine at a party might be okay with a resilient house plant in a big pot, I would not make a habit of it. "Dozen litres" is a lot.
Beds and compost heaps, being larger, and getting water from elsewhere should not be such an acute problem. I would not use the wine for watering though.
One should not feed animals or plants with spoiled anything, including wine. Coffee grounds - yes. Leftover wine, yes - I do it all the time. I own a wine store and my Anthurium is spectacular year after year. It gives me about 40 flowers that bloom from fall to spring.
