Lower PH with Coffee Grounds Test Results

Lower PH with Coffee Grounds test results & research results (Must Read)


SPENT COFFEE GROUNDS are increasingly recommended by professionals and gardeners as a sustainable way to improve your garden soil and provide nutrients to your plants. Claims include improved soil structure, an ideal carbon to nitrogen ratio, improved fertility and provision of nitrogen1.

:nerd_face: However!!! …the scientific literature has not sufficiently assessed the impacts on soil and plant production.

Recent research conducted by Dr Stephen Livesley and Sarah Hardgrove from the University of Melbourne, has shown that fresh (uncomposted) spent coffee grounds, applied directly to gardens, can significantly decrease plant growth and development. This article reviews the case for using spent coffee in the garden and describes recent scientific findings and their implications.

Read full study here:


This is great info, @GreenCoat I dont think i would use grounds directly in the soil but would possibly use it to adjust my water ph. Plus coffee in a compost pile is a worm magnet!!

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Problem is that you use allot of coffee grounds to adjust if its out too far. How much is too much. Not worth the risk if you have another choice. I put way to much time into my first grow to use unsure methods… It’s like you’re caring for a living thing… well I guess it is alive in the sense of the word

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I hear ya, I get nervous with tryn new stuff. Im adjusting now with white vinegar and having great results so I probly stick with what i know.

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Vinegar, Interesting!

A natural alternative is always best as long I don’t find a study showing potential adverse effects😅

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Look forward to the white distilled vinegar study. If you find any negatives, I will be lookn for an alternative.

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So am I, if my soil is too alkyd and needs some ACID, vinegar works great. Trouble is going the other way, our rainwater is very acidic (pH4.5 or so) and after using baking soda to bring it up, I learned from other posters that it’s not good for the plants. Ok, a trip to the pet store for pH up is in the cards now.

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Worm castings or fish emylsion are great. I do my best to grow organically & only chemicals i use are ph up & down.


@DieHigh55 I never had to use baking soda, when you used it did you see any issues with the plants? I wonder what problems occur with it? If you use too much of anything it can be harmful. Im only using around .5ml of vinegar per gallon of water, which gets me from a 9.2 diwn to 6.4-6.5. The vinegar got me outta major nute lockout. Happy Growing!!

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Have you tested vinegar? PH the water with vinegar then let it sit for 4-5 hours testing every hour to see if the vinegar holds the PH level …? I know lemon juice doesn’t keep the PH level well.

Because that would mess with run off results or water change/flush results…?
If it doesn’t hold the PH well🤔

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That’s a good idea, I’ll do that and post the results.

My last crop was in coco and I had lots of problems stabilizing the pH. I used baking soda to bring it up and vinegar to bring it down and ended up with a “good but could have been better” crop. This crop is in soil and so far after 3 months and a few days and 16 days after flip, its going good…and fast! I’ll post a pic without lights later. In any case, I got some pH up at the pet store today, so I wont be using the baking soda anymore. I would think the combo of baking soda and vinegar in the water would add an extra boost of CO2 to the soil, which the plants might like. I’m also going to be a mad scientist and try @GreenCoat 's experiment to see if vinegar keeps the pH stable.

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@GreenCoat @DieHigh55 Just a thought:
If its not stable after 4-5 days what does it matter when you water every 3 days and the plants are sucking up the water in between this time? Plus doesnt wirm castings help stabilize ph which i use FF soil and nutes? In future grows i plan on a soil with lots of castings mixed directly with soil.

Opps my bad on the days vs hours!! @GreenCoat

I use Alaska ph down now because it was on clearance for 3 bucks. Before I used raw organic apple cider vinegar with the mother and had good results. It was also a lot easier to adjust the ph with ACV than what I’m using now.


And that’s what I did: I started with 400ml. of heaven sent rain water which pH’d at 5.7, added 1ml of 7% white vinegar. The first reading was at
1400 - 3.7
1500 - 3.4
1600 - 3.4
1750 - 3.2
1900 - 3.3
Conclusion: The vinegar seems to hold the pH pretty steady, so it would probably help to bring down the pH in highly alkyd soil. Do I get a Nobel prize for science now? @PigmanBBQ @shindig153


Love your work :slightly_smiling_face: now does vinegar effect the PPM of your nutrients? Or you use separately?

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The things I do for cannabis! Thanks, it was fun.


This is great info​:+1::+1::+1:


vinegar and white vinegar have places in organic gardening. Although white vinegar can be used as an herbicide, apple cider vinegar with 5 percent acidity has quite the opposite use. It can be used as a fertilizer to maintain healthy plants. Because apple cider vinegar is acidic, however, it is best to use it as a fertilizer for only acid-loving plants, such as blueberry bushes, gardenias and azaleas.

Pour 10 ounces of apple cider vinegar that has 5 percent acidity into a 10-gallon bucket.

Fill the rest of the 10-gallon bucket with water. Using 1 ounce of apple cider vinegar for every 1 gallon of water is ideal, but the ratio does not have to be precise to obtain good results. The goal is to water down the vinegar significantly so that it does not harm plants or soil.

Pour the apple cider vinegar-water mixture onto the soil around the roots of each plant you want to water. Although the vinegar is diluted, its acid still could wilt any parts of plants it touches on a sunny day. Use any watering method that works best for your yard, such as watering with a watering can or a sprayer.

You can use apple cider vinegar as your regular fertilizer or alternate it with a commercial fertilizer. Many gardeners experiment with using apple cider vinegar as a fertilizer to determine whether or not it works best for their plants.

Use an apple cider vinegar that has not had all the pulp filtered out because the pulp contains the most nutrients. Also use an organic apple cider vinegar so that you do not add residual herbicides and pesticides to your garden. @DieHigh55