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Question: For the past three years, our phlox has been turning yellow. We don't water in the evening. What could it be?
Answer: It's probably a fungal disease, which means it is systemic. A sulphur product would help, and if you have not tried that, do so. Follow the directions carefully. If you have not been overwatering, you might need to replace the plant. Three bad years might mean you should dig it out and fill the hole with compost so the soil can heal itself. Then look for a phlox that is guaranteed not to mildew. Find a well-drained spot in some sun. Phlox should be watered deeply and allowed to dry out before they are watered again. They hate soggy soil and need a good dose of compost at least once a year.
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