Should the Plants Be “watered” With Leftover Coffee (and Other Drinks)?
We all wondered as we carried a pile of nearly empty glasses and mugs from the workplace to the kitchen: what would happen if I threw them into my pot plant?
Probably nothing – at least not right away. While some common drinks should never be used to “water” plants, others are harmless or even potentially beneficial. It all depends on what types of compounds the drink contains.
Seltzer: Great
All drinks are mostly water, but seltzer water – even flavored water – is really close to plain tap water. It’s definitely more acidic thanks to its carbonation and flavoring essences, but most plants grow best in mildly acidic soil anyway , so that’s not necessarily a bad thing. (Soil PH for potted crops is 6-7, usually closer to 6.) An ounce or two of LaCroix flat pumplus is harmless, especially if you dilute it with tap water before watering the plants.
Regular tea and / or coffee: generally good
Our favorite caffeinated drinks are just dead plant matter and water, two of the three things growing plants need. (Light is third.) Said dead plant matter contains small amounts of essential nutrients such as phosphorus, nitrogen and potassium , which make the resulting drink slightly sour. In fact, leftover tea or coffee is a very weak fertilizer.
However, keep in mind that this only works if you are drinking black tea and / or coffee. For reasons that will soon become apparent, sweeteners and cream should never end up in your plants, especially if they live in your home.
Drinks, juices, dairy products, and other sugary or fatty drinks: a difficult test
If you’ve ever refused to dump the leftover wine bottle into ficus, your instincts were right – even if your reasoning wasn’t. Ethanol in small doses isn’t all that bad for plants, but the sugar and other carbohydrates in alcoholic beverages (and others) are definitely harmful.
Plants do not need carbohydrates, fats and proteins that make food nutritious for humans. While some sugar is not an immediate death sentence, with time to add nutrients to the plants, which they can not and do not want to use, kill them – if pests, they attract not yet completed their work. Insects love sugar, yeast, fat, and whatever they can collect; Pouring drinks with these ingredients into a small amount of potting soil is an expected ant or fungal mosquito infestation.
If the idea of watering your plants with anything other than clean water still makes you nervous, you certainly don’t need to. But if you leave a couple of inch coffee mugs around the house all the time, this is a good way to make the most of this liquid. Just remember that the dose creates poison: if in doubt, dilute the drink (no sugar / no milk) with tap water and spread over several plants.