Well fast forward to today and coffee is still a popular topic for gardeners. It is a little funny since for the most part coffee isn't grown here in the US, but we import and consume so much of it that it is a common household thing and something that people spend a lot of money going out and having a hot cup of Joe at a local coffee shop.
So the questions are ask a lot about acidity of coffee grounds, the effect of the coffee grounds, the availability of the nutrients in the grounds etc. So I found quite a few people are actually running tests on the grounds and determining the effects of coffee for gardens.
It turns out that most of the acid in coffee is flushed into the coffee we drink. So the grounds are pretty much neutral PH of 6.9. They have nitrogen in them and should be considered a nitrogen in your compost. There are traces of minerals in the coffee grounds, but generally not enough to be considered a soil supplement, but the fact they are there are beneficial for most soils with phosphorus, potassium, magnesium, and copper. The nitrogen levels are quite good, but not available to your plants until they are broken down by soil organisms like worms, fungi, and soil bacteria.
Many households have coffee grounds that they toss out instead of adding to a worm bin or to a compost pile without realizing they are tossing out black gold for your garden. Now the interesting part is this. You can call around to local dining places, and coffee shops and ask them about getting their coffee grounds. I have found that these places are happy to give them to you. I have a nearby coffee shop just this week that I called and asked if I can get the grounds. They were a little baffled by the request, but said come on over and they would give me some. When they handed me a garbage bag with coffee grounds they asked if I wanted any more... I said "I will take all of them you have". They went and gave me part of another garbage bag full. I asked if I could come by each day and they said sure, just call and let us know you will be coming by and we will set the coffee grounds aside for you to pick up. So I will be doing that starting this week. So free coffee grounds! And in a large enough volume that I should be able to keep adding the coffee to my compost, my worm bins, and even applied to my garden beds.
It is a win win for gardeners. Over time the nitrogen will break down and feed your plants. So it is a great soil amendment. Now who knows how long coffee will be free and abundant for gardeners. It really isn't a sustainable resource, but to take something that is going to end up in a landfill and to turn it into food just makes sense while we have it available to us. So don't hesitate to start saving and using your coffee grounds. Call around and get some and start to use them in your garden beds.
Here is the web article on the Starbucks Coffee Test. This gives you some details on the effects of coffee in your gardens. It is largely a myth that coffee will make your soil acid for acid loving plants. The same is also true about Pine needles and pine chips. It is a myth, the process of composting those materials returns them back to a neutral PH and has no acid effect on soils. So check out the article. Also here is a video talking about this same topic.
So consider coffee as soil amendment, compost, and worm food. It will greatly help your garden.
Take care and God Bless,