Plants, soil and pH

This is the weekend many of us have been waiting for. I am always told to wait to plant anything outside until the May long weekend. After much anticipation, it is finally here and I am really excited to get outside and garden up a storm. I have been thinking where to plant what and how well different plants grew last year. This has made me wonder if I need to take a really close look at my soil pH. It is important to know the pH of your soil as different plants like alkaline soil and some do not for instance. To be honest, I am not that interested in having expensive tests done, so I thought I would test it myself. Let’s get started.

*Remember to ask an adult before doing this experiment.

Materials

- sample of soil to test - head of red cabbage - kettle - water - heat proof bowl - cutting board - strainer or sieve - two white dishes - measuring cup - spoon - jar - medicine dropper or pipette

Procedure

1. The first thing you need to do is to make an indicator. A simple indicator to test for pH can be simply made with red cabbage.

2. Have an adult cup the head of red cabbage into fine slices.

3. Place the sliced cabbage in the bowl.

4. Fill the kettle full of water and allow it to boil.

5. Ask an adult to pour the boiling water over the sliced red cabbage.

6. Make sure the water covers the cabbage and allow it to sit until it is cool.

7. The water should be a brilliant purple colour.

8. Strain the cabbage from the purple water into the jar.

9. Set the indicator aside for now.

10. Place a spoonful of soil on the white plate.

11. Fill the medicine dropper with the indicator.

12. One drop at a time put the indicator on the soil sample.

13. Be careful how much you add, you do not want it to be completely saturated, but you do want enough of the indicator on the plate so you can see it. 14. Swirl the plate around. 15. Wait at least one minute. 16. Observe what you see. 17. Repeat again on the other plate so you can be sure of your results.

What is going on?

You should see the cabbage juice indicator change colour or remain the same perhaps; it will depend on your soil sample. If the cabbage juice turns red, the soil is acidic or in the pH range of 0.0-6.9. When the cabbage juice is blue or green the soil is basic or a pH of about 8.0 -14.0. A purple or bluish purple colour indicates that the soil is neutral or a pH of 7.0. The pH of soil is very important for different plants. Most plants do well in a pH of six to seven. Potatoes for example like a pH of about 5.06.5; carrots 5.5-7.0; lettuce 6.07.0. You can add some things to the soil in order to change the pH to better suit the plants that you want to grow. Make sure you talk to the professional at your local garden store for help

Patty Rooks is senior scientific consultant at PRAXIS, “Connecting Science To The Community.” Contact Praxis at praxis@praxismh.ca, www.praxismh.ca, Tweet or follow us @PraxisMedHat, or friend us on Facebook.