When most of us hear the word ‘bicarbonate’ we think of baking soda. In this case, we’d only be half right. Baking soda (NaHCO3) is sodium bicarbonate. Potassium bicarbonate is something else entirely. What is potassium bicarbonate? Also known as potassium hydrogen carbonate or potassium acid carbonate, potassium bicarbonate (KHCO3) is a white, alkaline solid used in fire extinguishers, wine making, to make club soda, and to neutralize acids. As a base, potassium bicarbonate is at the high end of the pH scale. If you have alkaline soil, studies have shown that using potassium bicarbonate does not alter sodium levels in your soil, plants, or runoff water. If your garden plants commonly suffer from fungal diseases, potassium bicarbonate may be exactly what they need. Unlike sodium bicarbonate, which leaves behind a sodium residue, ammonium bicarbonate (NH5CO3) contain nitrogen, and potassium bicarbonate (NH5CO3) contains potassium, both are important plant nutrients. Organic fungicide Potassium bicarbonate is an organic fungicide used mostly to prevent fungal diseases, such as alternaria blight, apple scab, black spot, blights, botrytis, downy mildews, molds, phytophthora, powdery mildew, and Septoria leaf spot. Once these diseases are in place, they are very difficult to get rid of, though potassium bicarbonate can certainly improve the situation. Research has shown that bicarbonates do, when they cover a leaf completely, slow the growth of and occasionally kill mold spores outright. For potassium bicarbonate to work effectively, it must be in solution. While some people promote the use of homemade mixes that use horticultural oils for this purpose, those oils can lead to phytotoxicity (plant poisoning), oily buildup on the leaves and in the soil, and the mix requires constant shaking to keep the oil and water mixed while applying. The ideal mixture of solution and treatment is sold under the name Ecomate Armicarb "O" 100 Fungicide®. Can you make your own potassium bicarbonate spray?
You can, but you shouldn't. As a big proponent of DIY just about everything, I must say that this case is an exception to that rule. While you can certainly find recipes for your own potassium bicarbonate mixture online, making it properly is not as simple as advertised. The truth is, it took years of research to determine the proper balance of ingredients that allow the antifungal action to occur, while sticking to plants, but not killing them in the process. The fine folks at The Garden Professors Blog Facebook Page directed me towards some good information along the same lines. Bottom line: potassium bicarbonate sprays are an effective prevention and treatment of many fungal diseases. But these mixtures are not something you should be trying to concoct at home. Instead, read labels and buy a product that will protect and not harm your plants. If you decide to use potassium bicarbonate in your garden, UC Davis recommends no more than 8 treatments a year.
42 Comments
Chuck
6/26/2019 01:20:50 pm
Ah, this is excellent information, thank you mucho!
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Kate Russell
6/27/2019 04:21:42 am
Thank you, Chuck!
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Mauritz Mostert
7/18/2021 06:29:54 am
According to Dr. Horst from Cornell University, potassium bicarbonate is effective at eliminating powdery mildew.
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beard
4/11/2020 07:41:47 pm
Tomatoes grown in soil with a little sodium always taste better, salt is good for tomatoes.
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Kate Russell
11/11/2020 05:30:06 am
I love salt on my tomatoes, but only after they are harvested. Putting table salt in your soil will eventually make gardening very difficult.
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Ann
5/13/2020 08:54:09 pm
It seems that GreenCure is no longer available. Do you still recommend not making your own from a recipe (1/2 t dish liquid, 3 T veg oil, 1T potassium bicarbonate, 1 gal water) found online? If you still don't recommend, what do you recommend we use?
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FeNiX
6/28/2020 09:22:48 pm
Thanks for this, however that doesn't look like it'd be a DIY recipe to make your own potassium bicarbonate...
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Kate Russell
7/2/2020 07:26:31 am
Hi, Fenix.
Ray
7/9/2020 11:00:58 am
What are you talking about? The recipe that person is describing IS using potassium bicarbonate in the solution. Did you read the post?
Sylvia Cox
6/18/2022 01:47:49 am
Your response makes no sense to me. The comment clearly provided a dyi receipe that uses potassium bicarbonate.
Kate Russell
7/2/2020 07:24:39 am
Hi, Ann.
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Kate Russell
7/11/2020 11:31:01 am
Sorry for the confusion, Ray.
Robert Suttles
4/29/2021 10:13:39 pm
no you can't I've wasted hours looking. are there any other companies or brands that do make it?
William G Robinson
11/9/2020 12:47:15 pm
Have you tested the PH of the solution once mixed. Also what was the PH of the water you were using?
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Kate Russell
11/11/2020 05:32:13 am
Ann,
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Cmit
8/4/2022 07:26:38 pm
I've used regular dish soap with absolutely no problem mix with potassium bicarbonate, neem oil has a fungus side, or on its own for aphids and other soft body insects.
Gerald A Verhoff
4/25/2022 04:54:45 pm
I want a proven fungicide to rid fungus from my tomato plants using a DIY formula using potassium bicarbonate.
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9/6/2023 09:03:57 am
For Early Blight organic powdered copper works well for me. It works better than the liquid form. 9/6/2023 09:05:28 am
Bummer they don't make Green Cure any more. It was hands down the best for powdery mildew.
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mark frazee
9/6/2023 10:57:20 am
Pure Crop 1 hands down the best thing on the market today for molds, mildews, and insects. OMRI listed. Expensive though. Brought my dead cucumbers back to life and producing in less than a week
Pat
9/22/2020 04:56:24 pm
Sodium is not a salt. Its an element in the periodic table. Sodium Chloride is table salt and not so good for your garden There are lots of salts which you will want to use in your garden. All dry fertilizers are salts.
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Kate Russell
11/11/2020 05:14:27 am
Pat, you are absolutely right on all counts.
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Kate Russell
11/11/2020 05:37:02 am
Also, Pat, thank you for pushing me to be more accurate.
Kira
9/26/2020 12:19:29 pm
Hi, I cannot find greencure at any hydroponics suppliers. Where can I get some?? Does anyone else make a suitable product that is available?
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Lucinda Karlic
6/30/2021 02:46:32 pm
Try Green Cleaner. Works great.
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Jason
9/27/2020 06:34:35 am
Potassium Bicarbonate (KHCO3) does not contain nitrogen and therefore doesn't leave behind any nitrogen as claimed
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Kate Russell
2/14/2022 10:13:57 am
Oh, dear!
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Cmit
8/4/2022 07:28:51 pm
I think the biggest point is that sodium is bad for plants, whether it's as a bicarbonate or is chloride salt.
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Janet Windham
10/16/2020 11:46:41 am
Just took down my zinnia garden and disposed of all stems, stalks and as many leaves as possible as they had fungus. However, I know there are leaves lurking in the soil. Now that the cutting garden is bare, am thinking about spraying the soil to kill any remaining fungus. Is this a good idea as part of a plan for next year?
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Kate Russell
10/21/2020 07:15:38 am
Hi, Janet.
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Janet Windham
10/21/2020 12:02:11 pm
Thank you Kate. I am thinking that it can't harm if it's not an overwhelming amount. It's been really dry here for the last few days. Am going to blow the garden of any remaining debris and bag as much as I can to be carried away. Then will apply the potassium bicarbonate with the mulch and cover with chips. It really helps to get confirmation.
Kathy
10/1/2021 12:39:03 pm
I found GreenCure online;
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eric
1/17/2022 07:58:15 am
"Ammonium and potassium bicarbonates contain nitrogen, an important plant nutrient."
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Kate Russell
2/14/2022 10:14:41 am
Jason told me the same thing.
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Kate Russell
4/29/2022 07:13:24 am
UPDATE: I have updated this post to reflect that the GreenCure I mentioned in the initial update seems to no longer be available. I did some research and found another product called Armicab. Armicab is 85% potassium bicarbonate. Please note, this stuff is tricky to work with. It can hurt you if used improperly. Please be sure to read and follow all of the directions on the package.
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mark frazee
2/5/2023 07:30:36 am
you can get food grade pottasium bicarbonate at nuts .com cheap
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Kate Russell
2/7/2023 06:18:05 am
I love Nuts.com! My husband is crazy about their salted roasted cashews.
mark frazee
2/5/2023 07:26:45 am
I have used potassium bicarbonate for years at a rate of 2 Tbls per gallon nothing else with no ill effects to my plants but you have to spray them every two or three days.the best solution I have found is pure crop one. Two applications good to go. It is made with oils but thanks to nano and colloidal tech. it evaporates strengthening the plant itself enabling the plant to fight off mildews and fungus. It is expensive but a little goes along ways
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Kate Russell
2/7/2023 06:17:20 am
Hi, Mark.
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mark frazee
2/7/2023 07:23:18 am
I love nuts.com too. they have so much good organicfoods I buy a lot of their powder good prices
Matthew
3/27/2023 10:07:30 pm
Hello, could you please go further into detail? What is nano and colloidal tech? Is that something you used or is in crop one? When you used just potassium bicarbonate and water you did it every 2 days until? It went away or forever?
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