I have some answers, I hope some other growers will chime in as well. You must dig the tuber before frost as it is not winter hardy in most climates. The tuber is a solid growth where the plant starts to grow, it is like an underground stem waiting to revive after the plant goes dormant. You let it go dormant after Labor Day, stop watering. If you planted in the ground and not in a pot, it may be difficult to tell if it even formed a tuber, you will have to dig it as your directions describe. I prefer to grow in a pot as it is easier to just store the pot over the winter.WHen the growth dies, you will have to poke around and see if it did form a tuber. IF they are doing beautifully, you may want to wait beyond Labor Day (which is usually about Sept. 5 here)and just enjoy them some more, but shorter days prepare the plant for dormancy.