I've been growing my own basil in pots on the kitchen window sill. But the leaves at the bottom of the plant are turning yellow and dying off, while the leaves at the top of the plant are a lush green. What's wrong ?.
They definitely know it's winter. We've still got basil plants grown from seed this year but they won't last much longer - a lot to do with serious lack of daylight.
Most varieties of sweet basil appear to be annuals, so it seems you're doing pretty good to keep them going into the winter.
The variety 'Tulsi' is considered a perennial in the tropics but grows as a half-hardy annual at best in northern climbs.