Look, We Need to Talk About Putting Coffee Grounds in the Garden


Coffee grounds in garden soil..is it all hype?

No doubt you’ve combed through many articles on this topic. Should I or shouldn’t I use coffee grounds in garden soil, whether as an amendment or fertilizer boost? SO maybe at this point you’re head is swimming. Maybe you’re rethinking it. Either way I’m glad you’re here so I can shed some light on this subject, and hopefully we can find some common ground (just had to say that!)

Yes, as a two cup a day drinker, I’m always gazing at my used grounds, I used to disembowel my spent k-cups and as an experimental move – emptied the contents into my houseplants. Did it do anything for them? Nope.

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coffee grounds in soil

Coffee grounds and Ph

The Ph level of coffee grounds, used and fresh, is always being debated, and for the most part, they are highly acidic. This is commonly known – after all, there are people who make the switch to “cold brew” which is a less acidic type, and some brands tout this , such as Kava. Many crop plants do fine in acidic soil, but some do way better with neutral or alkaline. In its post-brewed state, it is less acidic, but still present nonetheless.

Coffee grounds are anti-bacterial

Including those already spent. In order for soil to maintain good fertility and health it needs a bacterial colony working on autopilot in the background. The good bacteria helps keep the bad bacteria in check, something we learned in science class. So if there are good microbes and your friends, the earthworms, present int eh dirt, they could be toast. I don’t think you’d want to have that on your conscience…

The big bugaboo – Caffeine!

That’s right, that one chemical compound you rely on to get that kick in the morning, will do more harm than good for your plants. Caffeine is a growth inhibitor – likewise, tea and cacao plants, which are also caffiene prevalent, have the evolutionary advantage in that they can stifle the growth of nearby crops. Ergo, that could be the death knell for your flourishing veggies. The biggest reason not to do it.

Myth: Coffee grounds can be used to repel slugs and other pests

You’ve no doubt heard this one a time or two, I always sidestepped this one. Early on in the game, I knew from conversations with the local plant nursery owner that slugs and snails are lured in to fermented products. I made my own beer traps for my parents’ garden with a flat dish I buried a few inches below the dirt and then filled with some Old Milwaukee. The next day, I found those suckers have drowned . Boo-ya! I don’t know how the coffee grounds idea got started but I have to call b.s. here because no way do hops and yeast have any chemical similarity to coffee.

But there is some GOOD news…See, I told you this wouldn’t be a rain on your parade post!

Coffee grounds are great for…drumroll, please…

Getting rid of weeds!

Yep, that’s right. If nothing else, you can use a solution of it to rid yourself of those pesky dandelions and crabgrass. My backyard used to be 80 % weeds…disgraceful. In addition to vinegar, coffee grounds would have been another way to bag them once and for all, if I hadn’t been concerned about protecting nearby good plants. So if you use them, make sure you apply them strategically.

And furthermore….

Used coffee grounds have lots of great household uses. They can be used to clean and scour pots, they could be put into sachets for the lingering aroma. Just do not get caught up into the hype that they will enrich your garden soil!



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