I have a confession to make. I’m an absolute bear in the morning when I haven’t had my coffee. I know, I should probably work on that because when the zombies come, it won’t take long for the coffee to run out.
In the meantime, I’ll keep enjoying my coffee.
When the coffee is done, I dry out the grounds on some paper towels on the counter. I hate for them to go to waste, so I’ve been using coffee grounds in the garden. It helps feed the plants and it’s one less thing that goes down the drain or into the trash can.
If you’re not already using coffee grounds in the garden, you might think twice after reading this article!
Why Use Coffee Grounds in the Garden?
That’s lower than I would have guessed, but when you figure there are approximately 321 million people in the United States, the actual number of people who drink coffee is nearly 189 million!
No wonder there’s a Starbucks on every corner!
Do you know what all those coffee shops do with those used coffee grounds? Most of them put them in the garbage. They are completely wasted, just like so many other things in America. But we can put a stop to that — and we should.
By using coffee grounds in the garden, you’d be helping reduce the amount of trash thrown out each year… and they’ve got lots of nutrients your plants will love, too!
Nutrient Information for Coffee
First, let’s tackle a myth — coffee grounds should only be given to plants that thrive in acidic soil. While it is true that coffee is inherently an acidic drink, the used grounds are not acidic. The acid in coffee beans is water soluble. That means when you brew your coffee, the water pulls out the acid leaving the used grounds nearly pH neutral — between 6.5 – 6.8 pH (according to this research by the Oregon State University Extension Service)(pH neutral is 7).
That same report says that coffee grounds are 2% Nitrogen by volume. This means that every pound of coffee grounds contains approximately 9 grams of Nitrogen. The used grounds are also made up of .3% Potassium and .7% Phosphorus, giving used coffee grounds an overall NPK rating of 2 – 0.3 – 0.7.
How to Use Coffee Grounds in the Garden
As much as I love coffee, I don’t always drink all of what I make. I usually fix my percolator (I love this percolator my wife got me last year) to make about half a pot, and I drink two travel mugs about this size full. When I have leftover coffee, I usually pour what’s left into a gallon-sized tea pitcher, dilute it with water and feed it to the plants when I water them. Here is where you should be concerned about the acid content in coffee. If you are going to water your plants with leftover brewed coffee, be sure you’re giving it to plants that tolerate acidic soil — beans, broccoli, cabbage, carrots, cucumbers, onions, parsley, peppers, potatoes, radishes, rhubarb, sweet corn, sweet potatoes, squash, tomatoes, turnips, etc.
When it comes to using the actual coffee grounds in the garden, you can sprinkle them around plants like a mulch. Don’t spread it too thick, though — the grounds will crust together and form a barrier that will not allow water into the soil. Since nitrogen helps plants grow faster, any plant grown for its leaves fits the bill nicely — arugula, bok choy, cabbage, collards, lettuce, etc. You should understand that the nitrogen is released over time as microbes and other soil organisms break down the grounds, so the nitrogen is not immediately plant available. This is actually a good thing (unless you need a quick boost of nitrogen to your plants immediately, in which case I recommend a nitrogen fertilizer).
If you’re just starting to plant your garden, you could use a hand-held broadcast spreader (or a bigger broadcast spreader like this if you have a big garden) to spread out the dried used grounds in quick fashion. You could also broadcast spread the grounds at the end of the season when you do your fall garden clean-up.
If you’re just starting to plant your garden, you can add some used coffee grounds to the planting hole before you put the plant (or seed) in. This will release nitrogen slowly as the plant gets its start and help it grow bigger and stronger a little faster.
You could also just dump those coffee grounds into your compost pile. Used coffee grounds are considered “green” material (nitrogen rich), so be sure you’re adding enough “brown” material (like dry grass clippings and leaves) to the compost bin, as well. Microbes like fungi and bacteria, along with bugs and worms, chow down on all those coffee grounds (along with the other stuff) and turn it into nutrient-rich compost that can be used for compost tea, mixing with your potting soil, or tilling directly into your garden.
Since worms love coffee grounds, you could just add them to your vermicomposting bins for worm food. They love the bacteria that help break down the coffee grounds, so they eat the grounds, bacteria and all. The coarse granular grounds are also help to the worms for breaking down their other food. Just be sure you’re shredding lots of paper for their bedding, too.
Get Used Coffee Grounds for Free!
As I said earlier in the article, there are nearly 189 million people in the US drinking coffee on any given day. Lots of those people go to coffee shops — local “shoppes” as well as big chains like Starbucks and Dunkin Donuts.
Most of those shops toss the used coffee grounds into the dumpster ever day.
If you have a coffee shop near you (and you probably do), pick up the phone and call them, or go visit them in person. Ask them (preferably a manager) about what they do with the used grounds. If they’re just chunking them every day, ask if they would save them for you. Buy a 5 gallon bucket with a lid just for this purpose so you can leave it at the shop.
Sometimes those coffee shops are already saving grounds for other people. This doesn’t mean they won’t save some for you, too. I doubt that those people go pick up the used coffee grounds every single day (and you know there are buckets full of grounds every single day). Don’t get discouraged if they tell you they’re already saving grounds for someone. Just ask if you can get into the rotation. They’ll most likely be happy to add your name to the list.
Don’t forget to ask your friends, family and neighbors. If they’re not saving them for themselves, they may save them for you. You could do a coffee ground run once a week or once a month to swing by the coffee shops and friends houses that have coffee grounds saved for you. Then just take them all back and dump them into the compost bin! Give that compost a turn with a garden fork (or give it a twirl if you’re using a barrel bin like this)! Pretty soon, you’ll have some rich, usable compost.
More Tips for Using Coffee Grounds in the Garden
Keep in mind that coffee and tea are very similar, so if you brew a lot of tea, save those grounds and leaves for the compost bin, too.
Some folks claim you can use coffee grounds as pest repellents — those pests ranging from slugs and snails to cats and squirrels. Some people have even tested these theories (like Patrick Dolan of One Yard Revolution), and the cumulative results are mixed at best. You can certainly use coffee grounds in your garden for plant food and light compost, and you might get some pest deterrent… but I wouldn’t use them specifically as pest control. There are certainly other things that would be better.