Question: My violets have seen to suddenly stopped growing. The centers are tight and the new leaves seem to be deformed.
Answer: This question is one that we recently received by phone and that we found particularly interesting. The answer was obvious, but didn’t come to mind until the conversation was nearly ended and the critical information was finally divulged. The problem in this case was very acid water, or too low a pH. Neutral pH is 7.0 and violets prefer water and soil to be neutral to very slightly acid, in the approximate range of 6.7 to 7.0. A pH below 7.0 is considered acid, and above 7.0 is alkaline. If the soil/water becomes too acid or alkaline, nutrients in the soil become less available to the plant, so that even a well fertilized plant can suffer from malnutrition.
This particular grower had always used rain water to water her plants. Rain water can often be quite acid, but for this grower it had never presented any problems over years of use, and we had eliminated all of the other likely causes of the problems. it was then revealed that the water had been collected as runoff from the roof, and that the home had just been reroofed. It was only then that her plants had begun to show signs of distress. Coincidentally, at that time we were having gutters added to the back of our barn, to keep water from running off of the roof and onto the glasshouse that was being built below. I had been told that the roof shingles would make the runoff very acid, and had been warned that the acidity of the runoff would etch the glass over time. The answer was suddenly very obvious! The water that was being used to water her violets was now too acid. If it were to be tested, it’s likely that the pH would be far below 7.0. The previous, very old, roof had likely had enough of the acidic chemicals washed away over the years to make water collected from its runoff relatively harmless.
Even rainwater not collected this way can present problems. I learned this when I moved to our present home, in a relatively rural area removed from industry or heavy traffic. Water that I collected in standing (plastic) barrels was not as clear and clean as expected. Along with the rain water was a surprising amount of soot and grime–it certainly was far from pure. Of course, “city” and well water can also have their problems. In any event, it’s always a good idea to have the pH of both your soil and water tested, particularly if the source of either has changed.