I love my espresso coffee in the morning. It’s as much a routine in our house as anything we do. When the power went out in Summerland around 5:30 am two weeks ago my first anxious thought was “How am I going to make coffee?” Stovetop burner on the barbecue to the rescue!
All of the grounds that come from the stovetop espresso maker go into the compost bucket and from there into the bin out in the vegetable garden. They are an excellent source of nitrogen, as the grounds are 2% nitrogen by volume. Even though they’re brown the grounds are in fact ‘green’ when it comes to providing material for compost breakdown. As such they should be mixed with an equivalent amount of dry leaves, shredded paper or some other brown material.
Coffee grounds have been credited with a host of miracles when it comes to use in the garden. Whether they actually live up to their billing is another story as it appears that there hasn’t been much science devoted to proving the effectiveness. For example, coffee grounds are said to be useful in preventing carrot rust fly from laying eggs on carrots. Some sources say to sprinkle the grounds in with the seed when planting, others claim that they should be sprinkled into the rows. My parents have sprinkled them into the rows when planting and their carrots don’t have carrot rust fly, so there’s your proof!
Same with slugs and snails; the grounds are reported to effective in repelling them around plants. It makes sense, the grounds are abrasive and the soft-bodied slugs would not feel comfortable travelling over them. I haven’t seen any studies that prove that they work in this manner but we don’t see many slugs in our gardens here in the dry Interior.
An interesting possibility exists when it comes to disease suppression in soil. Studies suggest that bacterial and fungal species which exist naturally in decomposing coffee grounds prevent pathogens from forming. Controlled experiments on beans, cucumbers, spinach and tomato proved their effectiveness but it’s not known whether this would extend to the rest of the garden. I would say this falls into the ‘can’t hurt’ category.
Coffee grounds can been used as mulches in the garden if you drink a lot of coffee or can obtain grounds from the local shop. This would seem to be a likely use for the grounds but in fact they’re not all that suitable. The grounds are finely textured and compact easily, which won’t allow much water to pass through. Better to use them combined with bark mulch.
So, the compost bin is the best destination for your grounds, the jury is somewhat still out for insects and slugs and it may help to suppress soil-borne pathogens in the garden, or it may not. One thing is certain, coffee grounds won’t do any good for your garden if they end up in the garbage bin!

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