If they survive till spring you leave some in the ground and let them seed. beets are a biennial and seed in the second year. If you are into seed saving it is a great opportunity. If not, turn them under or compost them.

No need to throw them out. That would be a true waste. They are a great compost additive or beneficial soil amendment. Many use them as a ground cover/green manure that is then tilled in in early spring. So like farmer dill said just till them in if you don't want to let them go to seed.

How would I go about letting them seed? I'm new to this gardening thing thanks again guys

I have never seen a forgotten beet survive here in the North. Rarely some chard, specially if it had some leaf cover.

if they survive youcan harvest some excellent greens

Agreed with digdirt- you just pretty much leave them be to let the set seed. They will want to start sending out leaves when the spring hits, and a bit later "bolt" and start making flowers. I've had this happen with radishes too.

And if you are into eating beet greens, you could get in some early eating greens too if you like :) Again, just let them grow out their spring leaves.

I agree with glib that there's probably a good chance they won't make it through the winter.

Rodney

I'm in eastern PA too and did the same as mfran. The beet (tops) I didn't harvest really looked shot after the first hard freeze. From the top, they looked very dead. So it's possible they'll regrow new tops?