Sunday, September 5, 2010

PH and nutrient availability

Time spent improving the nutrient levels of your vegetable garden can amount to not much if one soil PH is out of whack. The PH level decides what nutrients are available to the roots of plants. The PH range which most plants thrive in is between 6 and 7.

Testing your soil takes about 30 seconds and a  PH soil test kit costs about $17 dollars and can be purchased from  me and most garden centres.

The test is as easy as getting a thumbnail sized piece of typical soil drip a few drops of purple liquid on it then squirting a bit of white powder on to the same area. Check against the colour chart to see what your sample PH is then relate that number to the next image The chart below has a green band which indicates the range which most plants thrive. When the soils PH is outside of this range some of the nutrients needed by a plant are bound up and unavailable to the plant even if that nutrient is present in large quantities.

dolomite is used to increase the PH of your soil
sulphate of potash is used to decrease the PH of your soil

Always adjust the soils PH slowly over time using no more than a hand full per square metre per three months.This slower rate of adjustment avoids shocking plants and soil microbes alike. Depending on the crop grown adjust the soil PH  as needed. next time you  are ready to plant, Google the PH range of your next crop and improve your gardening experience.


  1. Thanks Chris, very useful post for a beginner like me. I bought one of those kits during the week and will try it out over the weekend, and again once my garden beds are filled.

  2. How did it go? What was the PH like in your garden?