If you have a perennial aster (versus annual), we would cut them back to 6 inches after they bloom.
You could transplant the aster into the garden for the winter as long as it's six weeks before the ground freezes.
Or, you could literally plant the container in the ground. This is a bit riskier. Tip: Plant the pot at a slight tilt so it doesn't acculate water at the top and drown itself when snow thaws. Finally, you can store the aster in an unheated garage.
Either way, you'll want to give it a nice watering before the ground freezes.
If you have a perennial aster (versus annual), we would cut them back to 6 inches after they bloom.
You could transplant the aster into the garden for the winter as long as it's six weeks before the ground freezes.
Or, you could literally plant the container in the ground. This is a bit riskier. Tip: Plant the pot at a slight tilt so it doesn't acculate water at the top and drown itself when snow thaws. Finally, you can store the aster in an unheated garage.
Either way, you'll want to give it a nice watering before the ground freezes.