pH Matters – Ruth Coulson (Ruth is with the Australian African Violet Association and lives on the Central North Coast of NSW) (Originally published on the African Violets Down Under Facebook page.(www.facebook.com/groups/241227626277942/?fref=nf) That’s more than a catchy title. The pH of the potting mix and the water/nutrient solution you use for your African violets does in fact matter very much. The scale of pH indicates the acidity/alkalinity of the tested sample. A pH of 7 indicates neutral. Depending upon the pH the nutrients in the potting mix and in the water may be more, or less, available to the plant. There are excellent charts illustrating this point if you will do an internet search under “soil pH and nutrient availability chart”. You will see that the majority of nutrients are most readily available to be taken up by the plant if the pH is around about the neutral, or just slightly acid part of the scale. Recommendations for appropriate pH for African violets vary widely depending upon who is quoting them, however among most of the growers that I know, about 6.5 to 6.8 is accepted as suitable. That is what I aim for myself. You may think this doesn’t apply to you if you purchase your potting mix ready made up, but it does. You should take nothing for granted. Recently I have had a slight difficulty that I have realised is because some of my potting mix has become too acid. Once I knew that, it was easy enough to fix by simply adding dolomite lime. The mix then has to be left to stabilise and tested again before use. At the time I felt motivated to test some products (I am going to refuse to name them for obvious reasons) but the illustration shows the result. There are many ways of testing for pH, but the method with reagent and powder to show the colour is one that can easily be photographed to demonstrate the point I am making. You may feel the results are even a little alarming, but realise that only one of these products is intended for African violets. The others are intended for other potted plants. I have photographed the colour chart along with the tested samples. The two at the top are pretty worrying to me! |
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