Coffee grounds: can they really melt ice? Photo: carolinacompost.com
With winter upon us, winter garden myths come to the fore, notably popping up everywhere on social media … and one of them is that you can use coffee grounds to melt snow and ice. I’ve even seen usually quite trustworthy websites, like Huffington Post, promote the idea. But it isn’t quite exact.
Now, coffee grounds for ice control is not totally a myth either. Used coffee grounds can have a certain beneficial effect on unwanted snow and ice, but just can’t melt them on their own.
How Grounds Are Supposed to Help
The explanation usually given for why applying coffee grounds to ice or snow would be useful is that they’ll melt them because they are acidic.
Well, first of all, coffee grounds aren’t acidic … well, not really. Their pH varies, but in most cases, it will be close to neutral immediately after you’ve finished your cup of coffee: about 6.5 to 6.8. (7 is point-on neutral.) In most people’s gardening vocabulary, a pH of 6.5 to 6.8 is neutral.
Besides, whether acidity actually melts ice is a highly complicated question. Just about anything really concentrated that can dissolve will melt ice, whether acid or alkaline. Road salt, for example, the product most commonly used to melt ice and snow, is usually neutral to alkaline, depending on its purity. And coffee grounds are simply not concentrated acidity.
Pour Them While They’re Hot
Now, if you spread steaming hot coffee grounds on ice, that would melt it … a bit. But the effect wouldn’t last more than a few seconds at best, so that would probably not change the situation very much. It would actually be easier to pour your piping hot coffee on the ice (black would be best) and it would be just as effective. Coffee grounds, especially when soggy, just aren’t easy to spread!
Let the Sun Shine
Of course, if you spread coffee grounds on snow or ice on a sunny day, that could help. Especially if the temperature was fairly mild. Grounds being dark in color absorb heat and can indeed help melt ice and snow. They’ll sink right in … usually after a series of sunny days. That’s a secondary effect of spreading sand and grit on ice, too. Anything darker than snow would do the same thing. Mostly, though, it isn’t very sunny when it’s snowing, is it?
Grit Is Good
Where coffee grounds could be helpful in ice management, though, is that they have a coarse texture. If spread on ice (shovel the snow off first), they’ll act much the way sand and grit would and help keep your feet from slipping.
And unlike sand or salt, you don’t have to pay extra for coffee grounds: they’re a by-product of your usual domestic coffee-making. So, by using them as a source of traction, you’re recycling and that’s wonderful.
Safe for Plants
Also, most de-icing products are harmful to plants. Road salt especially. But coffee grounds are actually good for them, at least once they decompose. There’s a limit to that—growing plants in pure coffee grounds can kill them! —, but that’s not a limit you’re likely to reach simply spreading grounds on a sidewalk to prevent skidding. Fairly little of the grounds will likely end up in nearby lawns or flower beds. Most, you’ll have tracked them into your house over the winter, giving you a coffee-brown carpet. Charming!
Learn more about why coffee grounds can be good for plants in the article What Plants Like Coffee Grounds.
Where to Find Enough?
The main problem is likely to be collecting enough coffee grounds! I can’t imagine producing enough to cover my need for grit on my stairs and walkways, but maybe you drink a lot more coffee than I do.
So, start saving up!
Well, I know little more than nothing about ice. I got a picture of some for this morning, but only because it is so rare. I do have experience with coffee grounds though. Before the current ‘situation’ closed so much down, we used to collect buckets of grounds from the big cafeteria type kitchens here, for the compost piles. (It really is overrated in that regard too.) Anyway, it seems to me that even if coffee grounds helped with ice, that they would create a different problem with their mess. Well, there is no carpet in here.
The evapotranspiration idea David mentioned makes sense to me. I don’t create enough grounds to make that worthwhile, but know that if anyone truly wants quantities of coffee grounds, you can ask for them at various coffee establishments. I used to get them by the sackful at a local Starbucks.
You forgot to add ground unicorn horn, that what really melts ice & snow.
Sorry! Yes, unicorn horn… definitely not rhinoceros horn!
Hi, I have never heard the “myths” you list, acid etc but I do spread grounds on the asphalt park pad at the back of my yard. It is kinda rough surface and hard to shovel bare (lots of snow and cold here in Edmonton!). seems to me to be an ecological good trick and uses basic physics. Like you said, dark matter absorbs more heat than white snow and ice. It doesn’t cause melting which would just re-freeze, rather it is evapotranspiration…… going directly from ice to vapour. doesn’t take much sun to start the process. in the spring, just sweep and compost, not something to do with salty sand and gravel. and no worries of rusting the car. It does take some collecting effort, and yeah, does not spread easily when wet. lay it out on a baking tray to dry, then put in an old can (coffee can!) drying also marginally helps humidify the house. Win all around.
Good comments1 My problem is I simply don’t produce enough of it!