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Testing soil pH the Red Cabbage Style !!

March 1, 2013

Last few days I read Strawberryhill's post about the cheapest way to test soil ph using red cabbage. I followed the link and read the post by the same person (named Straw this time) at:


Then I went and do as the intructions said. Bought some red cabbage and did the experiment like a good scientist I was. The result is quite satisfying, which I think is accurate to the best of my knowledge. This could really be one of the most important gardening technic (aside from composting) one could learn from GardenWeb forum.

Main tool (red cabbage):

Pic of boiling red cabbage:

Done and discarded cabbage(the leave colour is paler):

Cabbage "water":

My soil in a white-bottom bowl:

My soil after mixed with the cabbage water and waited about 30 mins :

my soil water in a white-bottom spoon:

Some cabbage water mixed with a teaspoon of vinegar( also 30 mins later like Straberry said) :

Original cabbage water with nothing after 30 mins:

Please share this if you find this useful, and thank you very much Strawberry.

Comments (8)

  • strawchicago

    Thank you, ceth, for those great pics. you took. Your soil looks slight blue, slightly alkaline, around 7.2 to 7.3 ... I wonder how that would compare to tea leaves, at 7.2.

    I'll boil some cabbage, and test tea leaves against other reported values for cooked oat meal, rice, potato, bread, frozen cooked green peas, tomatoes... I might take some pictures. I can't test my soil since it's covered in snow.

    I posted the info. to alert folks about the danger of over-fertilizing. If the pH is between 6 and very alkaline, and if the soil is clay rather than sandy, there is no need of dumping nitrogen ... nitrogen is plenty in my clay soil of pH 7.7, and air is made of 78.09% nitrogen. I never fertilize my decidous trees, yet they are taller than my house.

    Nitrogen is needed only in pots or sandy soil that leaks out. After using chemical fertilizer that leaks out from pots, I switched to blood meal (has iron) and dried chicken manure. Both are sticky, with slow-released nitrogen ... so plants in pots stay dark green.

    To fix my heavy clay at pH 7.7, these holes are from best to OK for my roses.

    1) Hole mixed with pine fines (pH 4 to 5), lots of blooming from the humic acid released by decomposed pine, and its 21% water-retention ability.

    2) Hole mixed with leaves - lots of bloomings. NPK of leaves is 0.8 / 0.35 / 0.2 Leaves retain water well, and phosphorus is released with decomposed organic matter.

    3) Hole mixed with grass clippings - kind of stingy, it might be from the high value of nitrogen. NPK of grass is 4 / 0.5 / 0.2 ... my clay retains nutrients well so higher in nitrogen can make it stingy.

    Below is a picture of own-root Sonia Rykiel rose turning chlorotic from nitrogen and iron leaching out of a pot (I watered it with soluble NPK of 18-24-16, with 0.1 iron, plus a high nitrogen soluble NPK of 32-10-10, with 0.33% iron).

    Compare that to the dark green, own-root Golden Celebration rose to the right. It's planted in heavy clay mulched with horse manure and alfalfa meal. Both are slow-released nitrogen, and horse manure has iron to make it dark green.

  • TheMasterGardener1

    "This could really be one of the most important gardening technic (aside from composting) one could learn from GardenWeb forum. "

    Well, its time for me to spread the word. Wow, this is really going to help big time!

    Now let me go and grow some cabbage so I can then use it to test the area I grew it in......... ;)

    This post was edited by TheMasterGardener1 on Fri, Mar 1, 13 at 13:43

  • strawchicago

    Hi MasterG: I know you are just joking, so I take it well. Humor is badly needed in any forum. One time a lady gave us a loaf of homemade bread, I made a careless joke, "it's going to be hard like a rock." She overheard and confronted me, "What did you say?" I was so embarrassed and complimented her profusely. I meant to be funny, but she was hurt. There's a few advantages of the red-cabbage-pH test:

    1) To test a big pile of dirt before spending $100 to $200 ordering one. My pile was tested alkaline at pH 8 ... they put lime to suppress weeds and to deodorize. It smelled good, no weeds, and my tomatoes grew well. Compare that to the stinky cow manure, acidic pH, but put so much weeds in a spot.... I still have to weed after 5 years.

    2) To test the horse manure I get. The stable in zone 5a put lime to deodorize the enclosed stall. In the spring, the manure isn't bad, around 7.4 pH. In late fall it's much more alkaline, above pH 8.

    3) To test the bagged soils I get. I paid more money to get Scott's bagged top soil, after it showed clear, or neutral in red cabbage. I didn't get any more of the cheap type, EarthGro, that tested deep blue.

    4) I paid $5 for a bag of mushroom compost years ago. I tested the left-over stuff, it's as green as baking soda (pH 8.3).

    5) To test one's tap water. Red cabbage is purplish in distilled water, but blue when boiled in my tap water, pH of 8. Fish-tank litmus paper showed the same alkaline pH.

    Some cities put lime the water so pipes won't corrode. Disadvantage? Phosphorus, necessary for blooms and root growth, is bound up with calcium or magnesium when the soil /water is alkaline. I solved the problem by using high phosphorus SOLUBLE fertilizer during hot summer months, when roses get tap water (pH 8), rather than rain water (pH 5.6).

  • TheMasterGardener1

    What? I really just may grow some cabbage to then use it to test for pH in the same area I grew it in. Sounds like a good idea to me? ;)

    This post was edited by TheMasterGardener1 on Fri, Mar 1, 13 at 13:50

  • strawchicago

    That's funny, MG, I had a good laugh. Thanks.

    MG: Since I have bread as one of the pH indicator, you can also grow bread, then test the pH of bread. Here's the instruction on how to grow bread:

    â¢Posted by colleenoz (My Page) on Sun, Jan 6, 13 at 0:20

    Speaking of Cooper eating the mistakes, I am reminded of the story (think I read it in a women's magazine) of someone who tried breadmaking and couldn't work with the dough. So she decided to bury her mistake in the garden to hide it rather than put it in the bin where it might be spotted by a family member. The next day, one of her children came running in to tell about the huge weird mushroom thing erupting from the ground in the garden. Yes, it was the fermenting dough rising up through the dirt! :-D

  • annpat

    GAK!!! That wasn't yeast rising.

    Here is a link that might be useful: Bread dough in garden bed

  • ericwi

    Madison city water has pH around 7.6, with abundant calcium and magnesium. It is true that our water leaves deposits of lime in teapots and around faucets, and we have a water softener in the basement. However, I don't think that the city adds lime to our water. Our municipal water wells are drilled down into a limestone aquifer, and the groundwater picks up calcium and magnesium carbonate from the limestone.

  • strawchicago

    Hi Ericwi: I'm glad to hear from you, thanks for the info. I have well water, with plenty of white deposits. We kept unscrewing the shower head to soak in strong vinegar or CLR de-mineral solution. It was a hassle until I found the trick of putting the solution in a heavy plastic bag, rubber-band the bag around the shower head, leaving it overnight. Clogged up shower head is one draw-back of hard water.

    A friend softened his water, and his blood pressure sky-rocketed ... he no longer add that stuff, per doctor's advice. Fifteen years ago I had a landlord that used lots of water-softener, her son died of a stroke in his early 50's .. she was depressed and died a few years afterwards.
    That's why I never use water-softener in our 12 years of hard well-water. Our water won the county's best-tasting award, sweeter than bottled mineral-water. I tested the pH of bottled mineral water, it's 7.5, not as alkaline as my water at pH 8.

    I visited a friend in an apartment complex that used water-softener, I found his water to be quite salty ... I had to carry my own water when I visited. BTW, my blood pressure is 104/80, I'm in my 50's, my Dad died of a stroke, so I watch my salt by using potassium salt, or lite salt.

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