Basil plant too old?
My basil plants don't really seem to thrive. I have 3 plants, which are quite old now (maybe 1-2 years old). They grow a bit, but the leaves are always quite small, and they never seem to product enough to make pesto.
I'm wondering if maybe the plants are just too old, and need to be replaced, or am I doing something wrong? Do basil plants have a useful lifespan, or can they produce indefinitely?