Full Member
Posts: 10
Joined: Mon Mar 19, 2012 12:56 am

Coffee to raise the acid in soil

Well thats the question does it or doesn't it. It seems like a lot of people say it does but most of the research suggest it doesn't .Anyone have any thoughts on this.' I have a major source of coffee grounds ,I want to lower the PH in my soil but if it can't be used directly in the soil I can always put it in my compost pile

User avatar
Mod Emeritus
Posts: 7646
Joined: Tue Jun 24, 2008 1:04 am
Location: Oregon

I don't use coffee grounds to acidify soil. I just put them on my compost pile. I've heard that most of the acid is leached from the grounds as coffee is brewed. For myself, unused ground coffee is too expensive to use in the garden. You might have better luck if you use both the used coffee grounds and any leftover coffee. The leftover coffee might contain more acid.

If you're curious, you could do a quick test with some litmus paper. You can even make litmus paper at home pretty easily. :)

Greener Thumb
Posts: 955
Joined: Sun Apr 04, 2010 3:29 pm
Location: Central PA

coffee / coffee grounds are on the acid side of neutral.

if one pours a cup of water into the ocean, does the sea level rise?
the technical answer is "yes" - the practical answer is no.

one reason so many of "these things" are "true" but "not true" is similar - it takes a very large amount to actually make a measurable difference.

the mass of the (dry) coffee grounds in relationship to the mass of the (dry) garden soil is very very tiny.

yes you can work it directly into the soil, yes it can go in the compost heap. unless you need a dump truck to bring the stuff home, it's going to be a fairly minor impact.

User avatar
Posts: 29524
Joined: Thu May 01, 2008 7:21 pm
Location: Zone 6, NJ (3/M)4/E ~ 10/M(11/B)

Ever since I tried growing oyster mushrooms on used coffee grounds substrate, I've been wondering if the point of coffee grounds is that they help create a more fungal-friendly soil. According to Teaming with Microbes, fungal soil is naturally lower in pH because that's how the "mushrooms" like it.

A combination of coffee grounds and wood chip mulch perhaps?

Oh! That reminds me! I wanted to get some winecap mushroom spawn for my garden! Now where was that catalog....

Super Green Thumb
Posts: 6113
Joined: Sun Mar 28, 2010 11:43 pm

and add them to your potato patch. UCG may help against wireworm.

I'm still testing. This will be my second year with potatoes.


"If a man alone in the woods speaks, and his wife cannot hear him, is he still wrong?"

Super Green Thumb
Posts: 2661
Joined: Sun Apr 10, 2011 2:52 am
Location: SE-OH USA Zone 6-A

Organic material may start out acidic, but as decomposition finishes, the end product is mostly neutral.

No amount of pine needles, coffee grounds, or bark, acidified my soil (for blueberries) adaquate to my need.

If you want to acidify soil, permanently its sulfer. or it's not gonna happen.

Full Member
Posts: 48
Joined: Sat Mar 31, 2012 6:43 pm
Location: West ~ zone 11

I'm using coffee grounds on my tomatoes, next is the green beans & cuc's. Whew, I'll have to drink alot of coffee to help my veggies get their caffeine fix, lol. :lol:

Full Member
Posts: 11
Joined: Mon Apr 09, 2012 9:53 pm
Location: Michigan, USA

Like what they said, it doesn't really have much of an impact when it comes to the acidity of the soil. But if you have slug problems, ground coffee will do the trick for you : )

User avatar
Full Member
Posts: 20
Joined: Wed May 23, 2012 8:30 pm
Location: Illinois/Iowa border

coffee grounds

I used coffee grounds and egg shells on my calla lillies last year and now this year I have put my first treatment on them I don't know if it helps I had googled info on growing my calla lillies last year and this was a suggestion it didnt hurt anything but am not sure it help either I am just hoping I have more lillies this year than I did last year thank goodness we had a mild winter cause I forgot to dig bulbs up but they have come back up in one spot almost looks like double of what I had last year no flowers yet but lots of green shoots keeping fingers crossed if anyone has suggestions or help for me it is greatly appreciated thanks

Return to “Organic Gardening Forum”