Cheapest way to test soil pH using red cabbage

strawchicago 5a IL(zone 5a)May 31, 2013

My limestone clay, pH 7.7, keeps the surface dry and alkaline, resulting in no-spray garden with clean roses. Soils that lack calcium often result in balling, botrytis, and weaker cell walls, which are susceptible to fungal diseases. Calcium, potassium, and phosphorus are all essential for strong root system.

Best to test your soil pH and tap water, before you add gypsum. There are other types of calcium if your soil is acidic, posted in the thread, "Types of Calcium ...."

Chop 6 leaves of red cabbage leaves, boil in 2 cups of DISTILLED water, use the hot juice and pour on top of samples of soil taken from your garden, wait for 20 minutes, if the juice on top is clear: neutral. If pink: acidic soil. If blue: alkaline.

Also boil some red cabbage in your tap water, if it's way-more blue than the red cabbage boiled in distilled water, then your tap water is alkaline. The pH of my tap water is 8, and Annie L. McDowell rose hated it. I had to lower my tap water with citric acid.

Citric acid is sold at the Health Food store, 1 lb. for $10, sold for sprouting. Roses root better if the pH of tap water is brought down to 5.6 as in rain water. I no longer use vinegar nor used lemon to bring down the pH 8 of my alkaline tap water (burns in hot weather). I find that a tiny bit of gypsum (calcium sulfate) neutralizes the bicarbonates (hydrated lime) in my tap water.

Below is Annie L. McDowell rose, 100% thornless, great scent that smells like lavender/lilac. It has the strongest scent among the 70+ roses that I grew for the past decades (I'm down to 55 roses now).

Annie is a musk, prefers slightly acidic. To prevent balling, I fertilized Annie L. McDowell rose with gypsum (calcium sulfate). Picture taken late May, after died down to few inches due to mid-April snow in my zone 5a.

Here is a link that might be useful: Cheapest way to test soil pH using red cabbage

This post was edited by Strawberryhill on Sun, Sep 29, 13 at 11:21

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Another very educative write up. Thanks for the info. BTW, can we use the common green cabbage for this test or it has to be the red cabbage only.

    Bookmark   September 8, 2013 at 11:41AM
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strawchicago 5a IL(zone 5a)

Hi Khalid (RoserianPk): I'm glad to hear from you. I miss your insights and questions which help me to dig for useful info. Without your questions in English Rose Forum, I would not had found the info. to benefit others.

Only red cabbage works. Litmus paper is based on lichen that changes color, but red-cabbage has a wider color range than litmus paper.

Boiling red cabbage in distilled water produces a hot juice which helps to dissolve the soil. It's very accurate if you let 1 large tablespoon of soil SOAK for at least 1/2 hour.

These are advantages of red cabbge juice over pH meter:

Does not need to calibrate, even the $200 pH meter needs recalibration before each use to be accurate.

Prolonged soaking released soil elements to yield the most accurate result. Coffee grounds is known as a buffer. Folks tested with pH meter reported wrong result of its being acidic. I tested coffee grounds in red cabbage juice, it's pink at first, but after 1/2 hour soaking, the solution became clear (neutral). Organic matter acts as buffer to neutralize soil, thus good for any pH.

You can test many samples of soil from your garden at the same time. I did that and found the hole fixed with pine bark (pH 4.5) became clear (neutral) in red cabbage juice. I found that decayed grass is slightly alkaline, versus my very alkaline rock-hard clay.

Below is an accurate color-changes in red cabbage juice, and its pH. If I test my soil when it's bone-dry, that's the result I get. But if I test my soil after it rains (pH of rain is 5.6), then my result is less alkaline.

Here is a link that might be useful:

    Bookmark   September 8, 2013 at 12:20PM
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strawchicago 5a IL(zone 5a)

There's a process called "Acid phosphatase" which cluster-roots secret acids. It's most efficient in sandy or fluffly soil, where roots can expand and get the oxygen needed. That's not the case with my compact heavy clay, where plants turn yellowish.

I have a rose seedling grown from seed. At first it's pale and yellowish in potting soil. After 7 months, it becomes green. It's planted in fluffy potting soil, which helps cluster root to secret acid in unlocking nutrients tie-up.

Here's a quote from the below link: "Some plant roots, especially cluster roots, exude carboxylates that perform acid phosphatase activity, helping to mobilise phosphorus in nutrient-deficient soils."

Below is my thornless seedling of Yves Piaget, picture taken September 13, in hot temp. above 90:

Here is a link that might be useful: Wikipedia on Acid Phosphatase of cluster roots

This post was edited by Strawberryhill on Sun, Sep 29, 13 at 11:24

    Bookmark   September 15, 2013 at 12:56PM
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strawchicago 5a IL(zone 5a)

Keeping the surface dry and alkaline helps with fungal prevention. Maintaining nature's balance of microbes helps roses to be healthy.

I found a blog by Cathy and Steve in Newburyport, MA, with 230 roses. They successfully use organic ways against black spots, see their blog in the below link, here are excerpts taken from their site:

1) sprinkle cracked corn.

2) "We began spraying with Rootshield, a patented formulation of Trichoderma in a wettable powder in the late summer of 2009. The results were dramatic and more effective than what we previously saw with cracked corn alone.

3) "Spraying regularly with our home made solution of peppermint or spearmint tea, canola oil, homemade garlic oil, clear soap, and other all-natural insecticidal agents helps to control not only blackspot but powdery mildew and insect pests as well."

4) "Because of our koi, we can't use pyrethrums in our garden either. For us, weekly spraying with either a garlic oil or mint based solution that includes baking soda adequately treats such pests as thrips, aphids, and spider mites and keeps a lid on powdery mildew as well."

Here is a link that might be useful: Cathy and Steve Garden with 230 roses

    Bookmark   October 7, 2013 at 11:17AM
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strawchicago 5a IL(zone 5a)

The role of soil bacteria in suppressing pathogenic fungi like rust and blackspot is documented by Penn State Extension on the use of Bacillus subtilis to protect leaves of Goldenrod from rust and fungal leaf spots.

Bacillus subtilis is a type of bacteria found on healthy soil, also in manure of animals that eat plants. It was used to treat dysentery in WWII. See link below:

Here is a link that might be useful: Penn State Extension Plant Pathology and prevention

This post was edited by Strawberryhill on Wed, Oct 16, 13 at 14:43

    Bookmark   October 10, 2013 at 6:26PM
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strawchicago 5a IL(zone 5a)

I recently tested the pH of the soil in the root-zone of roses affected by black spots in our non-stop late fall. They tested from neutral to slightly acidic, perfect range for black spot germination. Wikipedia wrote on how soil become acidic over time:

"Rainfall: Acid soils are most often found in areas of high rainfall. Excess rainfall leaches base cation from the soil .. . Additionally, rainwater has a slightly acidic pH of 5.7.

Fertilizer use: Ammonium (NH4+) fertilizers react in the soil in a process called nitrification to form nitrate (NO3−), and in the process release H+ ions.

Plant root activity: Plants take up nutrients in the form of ions (NO3−, NH4+, Ca2+, H2PO4−, etc.), and often, they take up more cations than anions. However plants must maintain a neutral charge in their roots. In order to compensate for the extra positive charge, they will release H+ ions from the root.

Some plants will also exude organic acids into the soil to acidify the zone around their roots to help solubilize metal nutrients that are insoluble at neutral pH, such as iron (Fe)."

Here is a link that might be useful: Soil pH - Sources of Acidity and Wikipedia

    Bookmark   November 3, 2013 at 10:09PM
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This is interesting and I might have to try this. Quick question to clarify instructions.

2 c. of beet water over 1 Tbsp of dirt? Or, can I use the 2 c. over multiple tablespoons of dirt?

    Bookmark   November 6, 2013 at 11:22AM
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strawchicago 5a IL(zone 5a)

Hi Zapod42: I'm glad to hear from you. Good questions. I put 1/4 to 1/2 inch. of violet juice above many samples. The details I wrote for English Roses Forum can no longer be googled. So I re-post here:

50 cents red cabbage and $1 distilled water. Rain water pH is acidic around 5.6 versus my tap water at pH of 8. That's why you need distilled water to boil red cabbage, resulting in a VIOLET solution. When I boiled red cabbage in my pH 8 water, I get a BLUE solution... shortcut to see if your water is alkaline or neutral.

I use tiny plastic cups and place samples in separate cups: 1 teas. vinegar (pH 2.2), 1 teas. baking soda (pH 8.5), 1 Tbs. of regular MiracleGro potting soil (pH 6.5), 1 Tbs. of peatmoss (pH 4), 1 Tbs. of crack corn, or crushed popcorn kernels (pH 4), 1 Tbs. used coffee grounds (neutral pH, a buffer, clear after 1/2 hour).

One tablespoon of soil from different locations in your garden placed in separate pre-labeled cups. Other indicator samples: pine bark (4.5), tomatoes (4 to 4.5), potatoe (5.4 to 5.9), whole wheat bread (pH 5.5), frozen cooked peas (6.4 to 6.7), cooked brocolli (6.3 to 6.5), cow's milk (6.4 to 6.8 pH), lettuce (5.7 to 6), cooked oatmeal (6.2 to 6.6), cooked rice (6 to 6.7), tea (pH 7.2), and egg white (pH 8).

You can also use freshly fallen leaves - See below:

Most acidic is Eastern Redbud (pH 4.3), Virgninia pine (pH 4.4), sugar maple (4.5), black maple (5.4), black walnut (pH 4.6), white oak (4.6), black oak (5 to 5.5), white ash (5.8 to 6.1), American Beech (5.8 to 6.9), flowering dogwood (5.5 to 6), Slipper elm (7 to 7.9), Hackberry at pH 8.

If the leaves are fully-decomposed over a year, they become slightly alkaline, pH 7.3, according to University Illinois Extension. Same with 100% decomposed grass, slightly alkaline.

If you test many samples, chop at least 4 cabbage leaves. Boil 2 cups of in DISTILLED WATER for 10 minutes, discard the solids. The purple juice works best when hot. Distribute the juice in cups, mix each sample with a spoon, and WAIT FOR AT LEAST 20 MINUTES.

If your soil is neutral, the juice will be clear like coffee ground or Organic potting soil (both are buffers, takes time to clear up). Most acid is fuchsia pink like vinegar. Dark pink is pH 4 (peat moss, pine bark, cracked corn and tomatoes). Medium pink is pH 5.5 (leaves, potatoes, and bread). Slight pink is pH 6.5 (MiracleGro potting soil, milk, oatmeal, and rice).

Light blue is slightly alkaline (decomposed grass or tea), medium blue is my 7.7 pH soil, dark blue is pH 8 egg white, more green is baking soda (pH 8.3), and bright green is wood ash at pH above 10.

Red cabbage juice has a wider range than litmus paper. It's more accurate than pH meter, since soaking allows the juice to interact with soil elements. Gracin from Florida posted a picture of how she did it, see below link:

Here is a link that might be useful: Cabbage juice soil test done by Gracin

This post was edited by Strawberryhill on Mon, Jul 28, 14 at 12:02

    Bookmark   November 6, 2013 at 12:36PM
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strawchicago 5a IL(zone 5a)

A quick way to test only a few samples: chop 1/2 cup of red-cabbage, put in coffee cup & fill with DISTILLED water. Cover lightly with wax paper, and nuke in microwave for 2.20 minutes. Let it sit for 10 minutes, then test your few samples. I use tiny fruit-cups, and pour the juice when it's hot, so it dissolve soil element better.

    Bookmark   July 28, 2014 at 11:59AM
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jim1961 Zone 6a Central Pa.

Great tip Strawbhill!

    Bookmark   July 28, 2014 at 12:05PM
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bart_2010(8/9 Italy)

I finally found red cabbages, at a supermarket inthe south of Tuscany,but now I see that the purified water I have is "demineralizzata",not "distillato" (I am presuming that the former is dimineralized water,the latter distilled). It is advised for use in irons, car batteries,etc. Can I use this for this red cabbage PH test,do you think, or must I use only distilled? thanks, bart

    Bookmark   September 10, 2014 at 12:11PM
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strawchicago 5a IL(zone 5a)

Hi Bart: The demineralized would be fine, it's the minerals that raise the pH. I bought some "mineral water" and tested its pH with fish-tank litmus ... it was quite alkaline, around 7.6 ... but not as alkaline as my hard-well-water, pH 8.5, which leaves whitish deposits on my pots.

Demineralized water is even better than distilled water, I check on bottled-distilled water, it's pH is slightly acidic, like 6.8, rather than neutral. I have a de-humidifier in the basement ... its water is pH 7, neutral. Most likely it's the same as your deminerlizata-water.

Rain water is acidic. My rain water pH in my Chicagoland is around 6, but the East coast (near Atlantic Ocean) has more acidic rain, at pH 5.6.

    Bookmark   September 10, 2014 at 2:31PM
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bart_2010(8/9 Italy)

OK, Strawberryhill, I did the test, but I think must've screwed something up:the water has remained exceedingly dark; black more than anything else! It seemed to me that six cabbage leaves were a lot for only 2 cups of water. Or perhaps I used too much soil in the jars? I plan to leave the samples for now, see if anything changes; maybe my mixture was just too dense???regards, bart

    Bookmark   September 18, 2014 at 6:50AM
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strawchicago 5a IL(zone 5a)

Hi Bart: I used 6 cabbage leaves with 2 1/2 cups of water, after draining off, it becomes 2 cups. I pour 1/8 to 1/4 cup of the juice over 1/2 tablespoon of soil. Mix with a spoon, and let it sit for 20 minutes. The juice above the soil will change either pinkish (acidic), clear (neutral), or bluish (alkaline).

If you use too much soil, then the mixture will be grayish or black. If so, let the soil settle down, after 1/2 hour, hopefully the juice above will show the color. Best wishes.
See below link for pictures of previous samples in red-cabbage juice.

Here is a link that might be useful: Red cabbage pH testing of many samples

This post was edited by Strawberryhill on Thu, Sep 18, 14 at 11:32

    Bookmark   September 18, 2014 at 10:11AM
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bart_2010(8/9 Italy)

OK,I definitely had too much soil and too little liquid. The liquid is now a very dark grey-blue...means soil is alkaline,I presume?

    Bookmark   September 19, 2014 at 10:24AM
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bart_2010(8/9 Italy)

OK,I definitely had too much soil and too little liquid. The liquid is now a very dark grey-blue...means soil is alkaline,I presume?
Looking at mine and comparing to the pictures on Internet,mine seems closest to around the ph 9 range;that is, slightly alkaline,but hopefully I'll get around to doing another test using less soil,and mixing with a spoon, too (I didn't do this before...) bart

    Bookmark   September 19, 2014 at 11:53AM
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strawchicago 5a IL(zone 5a)

Hi Bart: grey-blue means the soil is slightly alkaline, perfect for roses. The brighter the color is, the more extreme the pH. Gritty lime is BRIGHT blue, like the sky, at pH 9. Compared that to blood meal, grayish with a tinge of blue ... slightly alkaline, around 7.3.

Vinegar is BRIGHT shocking pink, pH 2 to 3. Compare that to my alkaline clay soil fixed with acidic pine park, just a touch of pink, but mostly clear, around 6.8 pH ... that's the place with the most black spots. Same with potting soil in rain water, when it's slight pink in red cabbage juice, means it's slightly acidic, perfect range for mildew and black spots germination. pH of rain is 6 in my Chicagoland, but much more acidic on the East coast, at pH 5.6.

The nursery's potting soil, or good potting soil, all register clear in red-cabbage juice ... they are neutral pH, means good buffering-action to neutralize the acid secreted by roots. Cluster-roots secret acid to utilize phosphorus from soil for blooms.

    Bookmark   September 19, 2014 at 11:58AM
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