Crystal rush on sweet potato
I saw this topic posted before but there was no comment that would answer my question.
Last summer I planted a sweet potato in standard soil in a pot in my room. It grew really fast — within a month I had a nice bush. But then the weather changed slightly, it got colder, and it started developing a kind of “rash.” At first it was white, then it turned black, and afterwards the leaves dried out and fell off. Over winter, the whole plant died back.
Despite this, the tuber is still growing well (I repotted it in spring and a new plant sprouted from it again).
I should mention that I live in central Europe, where the climate is cooler than what sweet potatoes usually need, but I keep the plant indoors on south-east windowsill. It's about 4-7hours of sun depends on the weather. I water it a least every week, if warmer twice a week. The room temperature fluctuates between 20–23°C.
Has anyone grown sweet potatoes in similar conditions? Or come across this kind of “rash” on the leaves? What should I do?