I read somewhere that I must have the pH for my clients at 6.5. How important is it to keep it at EXACTLY 6.5?
— Mark in Seattle
As long as your pH doesn’t drop below 5.5 or go above 7.0, you should be okay. The pH always fluctuates, especially when you water/fertilize your plants.
As the plants uptake the nutrients, the pH goes in one direction and when you add nutrients, the pH goes in the other direction.