Coffee bad for gardens

FILMNET · February 25, 2012

I have been reading here about coffee in my garden , Last year i put Starbucks coffee grinds 12-30 lbs on my dirt . I did this early winter, and some of my plants where i dumped the coffee were really small. I left the coffee because the ground was frozen was only in dirt for 1/2 on my garden. On this half I had 6 small plants all summer??? could the coffee be bad for these plants? And this year i only putting coffee grinds we use in my Compost. ??? they were wet when i got them 203 bags total. My garden is the bottom of a barn with horses taken down after 1905, My wife's great great grandfather never bought a car. Horses carriages only till he died

RayR · February 25, 2012

Too much of anything can be a bad thing. How big an area are we talking about that you applied 10-20lbs? (Is that dry weight?)
I prefer it as a compost ingredient, but some folks might find it beneficial as a thin mulch for some types of plants.

tjg911 · February 25, 2012

yeah i agree if that was in a 250 sq ft area maybe that's overkill in a 1000 sq ft that's probably ok. ocffee is an excellent amendment but coffee is acidic so it will lower ph if you use too much and ne soils tend to be acidic to start. how long have you had the garden, you should have soil not dirt. dirt is the worthless crap on the side of the road that is barren. maybe your garden is new and doesn't have a lot of organic material in it so plants are doing just so so. lot of factors w/o much info.

tom

janezee · February 26, 2012

Used coffee grounds are not acidic, nor do they acidify the soil. I was so disappointed to learn that after I put lots of them around my blueberries.
j

RayR · February 26, 2012

The initial acidity of coffee grounds can vary greatly, the PH can range anywhere below 5.0 to over 6.0. I recently tested one sample from our kitchen with my Digital PH meter and it came out at 5.7. Not terribly acidic. Unless you are growing plants in coffee grounds themselves as a medium, I don't think you'll get the full effect of the acidity, but then the PH will rise anyway as bacteria and fungi decompose the grounds. Adding them to compost will result in the same.
Adding them straight into the soil around plants is no guarantee of even a short term lowering of PH as the buffering capacity of your type of soil is a big factor.

z_willus_d · February 26, 2012

Janezee, I beg to differ. I've recently measured my freshly made soil for a new bed before and after adding coffee grinds, and the grinds definitely lowered the pH of near on 8 or 10 measurements repeated at the same location on the same day. I've measured it before in similar manners and found the same. I have a high accuracy/precision pH meter, which I trust to within at least .1 pH (probably more like .01). I was recently using Starbucks grinds mainly from their espresso machine (so finer than drip). I don't think the grinds are terribly acidic, but they're definitely south of neutral. I attached a couple pics from measurements I took some time ago. The first is of my worm bin where I recently dumped some coffee grinds (uncomposted); second is of the finished castings (composted).

Best,
Naysen

John3 · February 26, 2012

Just a note: If you are growing hydrangeas I have seen where when coffee grounds are added the flowers get tinted (like a stain)

OneDahlia · February 26, 2012

Quote:

Originally Posted by John3

Just a note: If you are growing hydrangeas I have seen where when coffee grounds are added the flowers get tinted (like a stain)

What color is the tint/stain?

John3 · February 26, 2012

Light brown to dark brown. If I remember correctly, dark brown where the petal connects and faintly on the petal. I have seen this on the White and Blue. Don't remember seeing it on the red ones.

Boutique Tomatoes · February 26, 2012

I have to think it more about knowing your soil. We have heavy clay soil that is alkaline, in the 7.5-7.6 ph range for 'good' garden soil, 8+ for most of the yard. This is with multiple soil tests, so I think it's accurate.

My original vegetable garden has had hundreds of pounds of coffee grounds added, the local Starbucks knows me well as the guy who comes in a couple of times every day checking for grounds, after dropping the kids off at school, after picking them up and whenever else I happen to drive by. The old garden is finally down to about 7.1 ph now. The natural soil here has calcium and sulfer PPM off the top of the range, the only thing I've added that can explain the drop in PH to me is all the coffee grounds. The tomato plants that always have done the best for in my garden are the ones that have been top dressed with even more coffee grounds throughout the summer.

Based on past experience and last years soil tests I've added over 1000 pounds to a new garden spot this winter. As a bonus this year I've saved all the bags to use as sandbags to hold down the edges of the plastic for the low tunnels I'm trying this spring.

If you have sandy acidic soil to start with the coffee grounds might be bad, but for my situation they seem to be doing good things.

mike5953 · February 26, 2012

Fascinating topic.
While I don't agree that coffee grounds are necessarily bad for gardens, it would seem that they are definitely more acidic that I had been lead to believe.
A quick bit of googling around revealed several sources that report that black coffee itself ranges in the high 4's to mid 5's. And that mid to upper 5's are considered "low acid" coffees. (No wonder it aggravates my acid reflux!)
I'm glad that I normally put them into the composter rather than directly into the garden.

FILMNET · February 26, 2012

I read on another website that 3 plants were grown inside under lights , 1 had only water, 1 had old coffee water and another had something else i forgot. But the coffee plant suffered the worst. We had so much rain last June the coffee must have been to much.
Here is a shot in June last year most coffee was to the left, there is big pot to the left, back, this was a nice plant, behind it was 2 small plants and left, front, has 3 small plants. These plants did not grow over 3fts high, and some were under 24 inch's high.

GaryStPaul · February 26, 2012

I'm no expert, but I do follow posts about coffee on the soil and compost forum elsewhere. The consensus there seems to be that coffee grounds (what's left after the brewing process) are very close to neutral. Put differently: brewed coffee is highly acidic, grounds are not.

bughunter99 · February 26, 2012

Were 100% of the small plants in the coffee ground area or did you have other plants do just great in the grounds? Were there any other factors associated with the smaller plants that you can think of? Longer time in shadows, competition from roots especially, or previous plants in that area where the big plants had virgin soil?

biscgolf · February 26, 2012

Quote:

Originally Posted by GaryStPaul

I'm no expert, but I do follow posts about coffee on the soil and compost forum elsewhere. The consensus there seems to be that coffee grounds (what's left after the brewing process) are very close to neutral. Put differently: brewed coffee is highly acidic, grounds are not.

this is what i have garnered as well.

February 25, 2012	#1
FILMNET Tomatovillian™ Join Date: Jun 2009 Location: North Charleston,South Carolina, USA Posts: 1,803	Coffee bad for gardens I have been reading here about coffee in my garden , Last year i put Starbucks coffee grinds 12-30 lbs on my dirt . I did this early winter, and some of my plants where i dumped the coffee were really small. I left the coffee because the ground was frozen was only in dirt for 1/2 on my garden. On this half I had 6 small plants all summer??? could the coffee be bad for these plants? And this year i only putting coffee grinds we use in my Compost. ??? they were wet when i got them 203 bags total. My garden is the bottom of a barn with horses taken down after 1905, My wife's great great grandfather never bought a car. Horses carriages only till he died Last edited by FILMNET; February 26, 2012 at 08:25 AM.

February 25, 2012	#3
tjg911 Tomatovillian™ Join Date: Feb 2006 Location: zone 5b northwest connecticut Posts: 2,570	yeah i agree if that was in a 250 sq ft area maybe that's overkill in a 1000 sq ft that's probably ok. ocffee is an excellent amendment but coffee is acidic so it will lower ph if you use too much and ne soils tend to be acidic to start. how long have you had the garden, you should have soil not dirt. dirt is the worthless crap on the side of the road that is barren. maybe your garden is new and doesn't have a lot of organic material in it so plants are doing just so so. lot of factors w/o much info. tom __________________ I need a hero I’m holding out for a hero ‘til the end of the night He’s gotta be strong And he’s gotta be fast And he’s gotta be fresh from the fight I need a hero I’m holding out for a hero ‘til the morning light He’s gotta be sure And it’s gotta be soon And he’s gotta be larger than life

February 25, 2012	#2
RayR Tomatovillian™ Join Date: Jun 2010 Location: Cheektowaga, NY Posts: 2,466	Too much of anything can be a bad thing. How big an area are we talking about that you applied 10-20lbs? (Is that dry weight?) I prefer it as a compost ingredient, but some folks might find it beneficial as a thin mulch for some types of plants.

February 26, 2012	#4
janezee Tomatovillian™ Join Date: Dec 2011 Location: Whidbey Island, WA Zone 7, Sunset 5 Posts: 931	Used coffee grounds are not acidic, nor do they acidify the soil. I was so disappointed to learn that after I put lots of them around my blueberries. j

February 26, 2012	#7
John3 Tomatovillian™ Join Date: Mar 2010 Location: Alabama 7.5 or 8 depends on who you ask Posts: 727	Just a note: If you are growing hydrangeas I have seen where when coffee grounds are added the flowers get tinted (like a stain)

February 26, 2012	#10
Boutique Tomatoes Tomatovillian™ Join Date: Feb 2011 Location: Northeast Wisconsin, Zone 5a Posts: 1,109	I have to think it more about knowing your soil. We have heavy clay soil that is alkaline, in the 7.5-7.6 ph range for 'good' garden soil, 8+ for most of the yard. This is with multiple soil tests, so I think it's accurate. My original vegetable garden has had hundreds of pounds of coffee grounds added, the local Starbucks knows me well as the guy who comes in a couple of times every day checking for grounds, after dropping the kids off at school, after picking them up and whenever else I happen to drive by. The old garden is finally down to about 7.1 ph now. The natural soil here has calcium and sulfer PPM off the top of the range, the only thing I've added that can explain the drop in PH to me is all the coffee grounds. The tomato plants that always have done the best for in my garden are the ones that have been top dressed with even more coffee grounds throughout the summer. Based on past experience and last years soil tests I've added over 1000 pounds to a new garden spot this winter. As a bonus this year I've saved all the bags to use as sandbags to hold down the edges of the plastic for the low tunnels I'm trying this spring. If you have sandy acidic soil to start with the coffee grounds might be bad, but for my situation they seem to be doing good things.

February 26, 2012	#11
mike5953 Tomatovillian™ Join Date: Oct 2008 Location: Raleigh, NC Posts: 97	Fascinating topic. While I don't agree that coffee grounds are necessarily bad for gardens, it would seem that they are definitely more acidic that I had been lead to believe. A quick bit of googling around revealed several sources that report that black coffee itself ranges in the high 4's to mid 5's. And that mid to upper 5's are considered "low acid" coffees. (No wonder it aggravates my acid reflux!) I'm glad that I normally put them into the composter rather than directly into the garden.

February 26, 2012	#13
GaryStPaul Tomatovillian™ Join Date: Mar 2008 Location: St Paul, MN Posts: 158	I'm no expert, but I do follow posts about coffee on the soil and compost forum elsewhere. The consensus there seems to be that coffee grounds (what's left after the brewing process) are very close to neutral. Put differently: brewed coffee is highly acidic, grounds are not.

February 26, 2012	#14
bughunter99 Tomatovillian™ Join Date: Feb 2010 Location: zone 5 Posts: 821	Were 100% of the small plants in the coffee ground area or did you have other plants do just great in the grounds? Were there any other factors associated with the smaller plants that you can think of? Longer time in shadows, competition from roots especially, or previous plants in that area where the big plants had virgin soil?