They will die back if left outdoors, just as soon as it freezes. They may die back due to the short day length even without freezing. If you leave them outdoors, you probably should bury the pots in a dry, protected spot, and give them little, if any water. They probably would not survive a hard freeze in the pots above ground, and even in the ground there is a risk they won't survive. They really need a full growing season to develop thick fleshy roots in order to over-winter well.

Thanks. I will let them stay outside until the first frost, then bring them inside into an unheated room, where I will keep the soil barely moist. The first frost isstill 2 months away, so I will take the pot of seedlings and repot into a pot that is a bit bigger.

Best advice is to separate the seedling as soon as possible into one per pot. If you leave it too long they can become an impossible nightmare to untangle as the roots snap easily.

Here is a link that might be useful: Seed tips