Is it proper etiquette to post more than one blog entry concerning used coffee grounds in the same month? Try to look that one up.
Yesterday I hefted another 60 lbs. of used coffee grounds home from Starbucks. What a great feeling.
But as chance would have it, a comment from Julie (who has a great blog called Julie’s Garden Ramblings) made me envious and curious. She said that I would laugh if I saw her stack, and that she’ll never run out. I’ve been trying to moderate my excess garden enthusiasms. Could I ever have too many coffee grounds?
I suspect that there probably isn’t a definitive answer to be had on the Internet. Too many LOUD ‘EXPERTS’ and not enough quiet experts. But you learn to pick your sources. If you can’t believe a research manager at Rodale, you’re a bigger skeptic than I am.
Anyway series of articles at Green Talk were very informative. All about coffee grounds and gardening, and I think from one of the quiet experts.
A few of the juicy bits below:
Rodale Institutes’ Respond to the Coffee Grounds Dilemma
I reached out for Rodale Institute since it was more likely they would have an answer for me. (If the name, Rodale Institute, sounds familiar to you, it is because many of you may know the name through the magazine, Organic Gardening, one of my favorite gardening magazines.)
Luckily I connected with Dr. Paul Hepperly, the research and training manager at the Institute, who is a well known authority in organic agriculture. Surely, he would know. (Fingers crossed.) He explained that once the coffee grounds are added to the soil, they start to decompose, and in turn, their acidity neutralizes. Ultimately, they are only adding nitrogen to the soil.
His suggestion was to side dress the plant with no more than one inch at a time. He further caution to not add more grounds until the original grounds had decomposed. Coffee grounds are solely a soil amendment and not a fertilizer.
He further explained that soil should have an organic matter of five to eight percent. At some point, there is a diminishing return if you keep adding coffee grounds, and your soil has already reached the eight percent threshold of organic material. It will not hurt the soil, but may not help much at that point. It is best to take a soil sample during the year to see what your soil needs.
As for compost, he suggested one volume green material to three volumes of brown. Coffee grounds are viewed as “green” material. (Whew. I was relieved that this matter was settled.)
My uses for coffee grounds are A) as worm heroin, B) as composted green matter, and occasionally C) as a top-dressing around the raspberry bushes.
One problem with using coffee grounds in the worm bin is the moisture content. In my experience it tends to make everything in the bin a little sloppy. Other than that I do believe that the worms would happily live in pure grounds. Fact way back when I was a little shaver, my neighbor kept his fishing worms in pure coffee grounds, and they looked very happy.
As far as garden compost and coffee grounds, the 1 to 3 ratio suggested confirmed what I had experienced as an effective ratio in my own piles. I rarely add un-composted grounds directly to the garden, and if I do, it’s with plenty of time allowed for their breaking down.
So in my long-winded way, the question has the same answer as my ‘Too much compost?’ question…moderation in all things. Boring, I know.