Have You Tried the Red Cabbage Test? This Fun Garden Alchemy Reveals Your Soil pH

Let’s face it: plants can be picky. One may adore the beaming sun, while another finds it to be its worst nightmare. One may thrive on near neglect, yet another will become temperamental if you don’t prune it in exactly the right way. And then there’s the potential issue of soil – its density, moisture levels, and acidity.

Soil pH is something many beginner gardeners forget to factor in when deciding what greenery to bring into their lives. It can have a huge impact on a plant’s ability to thrive because, after all, plants grow from the roots up. That’s why I was so intrigued when I came across a brilliantly simple way to test it in a video shared by gardening expert Simon Akeroyd on Instagram.

Fortunately, there’s a simple, incredibly nifty trick you can use to test your soil’s acidity that requires just three things – a red cabbage, some water, and a little patience. In the clip, Simon demonstrates how the cabbage soil pH test works, and it’s pure genius. Here’s how to try it yourself, as well as why it works.

How Red Cabbage Reveals Soil pH

Red cabbage contains a special molecule that changes structure when it meets acidity. This molecule is present in cabbage due to its rich pigment, making it ideal for testing soil pH because once it is altered, the color noticeably shifts.

As Steve Corcoran, a plant pro and the owner of Lawn Love, explains: "There is science behind this. Red cabbage contains anthocyanins, which are natural pigments that are water-soluble and are responsible for the color of many different fruits and vegetables.

"The molecular structure of anthocyanins actually changes when they become acidic, neutral, or alkaline, and that unique molecular structure thus alters their light absorption, changing the color."

It might still sound a bit confusing, but trust me, using red cabbage to test pH is actually very simple. Plus, there are ways to alter the pH of your soil once you know what you're dealing with if it doesn’t suit your planting needs.

How to Test Soil pH Using Red Cabbage

To test your soil pH using a red cabbage, you first need to buy one if you aren’t already growing it in your yard. Then:

1. Boil some of the cabbage leaves for three to five minutes until the water takes on the cabbage’s signature hue.
2. After the water has cooled and turned blue, pour your cabbage-infused water into a clear container through a sieve to ensure no debris makes its way in. Debris could potentially interfere with your results if it isn’t removed, so this step is important. A clear container is recommended so you can see the water more easily.
3. Now it’s time to test your soil. Simply stir a teaspoon or two of the soil you wish to test into the water and leave it for a few hours.
4. When you come back to check on the water, you’ll find out whether your soil is acidic, neutral or alkaline – depending on the color of the water.

Reading the Results

Depending on whether your soil is acidic, neutral, or alkaline, the cooled cabbage water will change color.

Angelika Zaber, gardening expert and lawn care specialist at Online Turf, explains what the different colors mean, as well as what to do if your results aren't clear:

"When exposed to acidic solutions, like acidic soil, your water will turn pink, while neutral soil tends to give the water a purple color, whereas alkaline solutions cause the water to turn green or yellow.

"If your results aren't clear and you plan to run the experiment again, I recommend boiling your cabbage in distilled water instead. Distilled water is neutral and free from minerals and impurities that could potentially lead to inaccurate results."

Of course, if you still aren't convinced, you should invest in a soil tester.

Best Soil Testers