This is the first time I planted Canna, and they came out beautiful. Living in Northern Jersey, we have already had a slight frost. The Canna`s are still pushing blooms. I have been told I need to dig up the bulbs before winter. My question is, "when"?

Wait until your canna plants have been touched by frost and have turned black. Then, quickly before the ground freezes, cut them down and dispose of the greenery. Dig up the bulbs and bring them into a warm place for the dirt to dry around them. I keep a large garbage can full of peat moss in an unheated room off the basement. Knock the dirt of the bulbs, bury them in moistened peat moss, cover with lid and leave them until spring. When it is time to plant them you will find them starting to grow in the garbage can. Good luck!

If you leave in Northern NJ the time to pull them might come soon. As someone already posted as soon as the leaves look they have been touched by the frost you need to take them out of the ground. I have not been successful in keeping canna tubers from year to year. I wish you luck in your attempt.