Are beets perennial? I have never tried keeping a beet contained by the ground...

I have never tried keeping a beet contained by the ground after growing season. What zone are they meant to be within? I have some really nice looking plants that hold very dim red leaves and I thought they would look nice in the flower garden. I am going to try it anyways but I am curious in the order of whether they will re-grow next spring contained by my zone 4 yard. Got a apt link for a history of beets? Thanks.
Answers:    They are a biennial.

The roots live within the ground through winter, and then grow again subsequent spring, sending up a flowering stalk, and then set pip.

The roots are fiberous and not so sweet if you leave them contained by the ground for the second year. But if you're growing them for the leaves, you should get another "show" the second year!
No they are not, as beside most veggies they are annuals...now some times the seed fall into the soil, and conclude up germinating, and by spring in that is a new growth. It happen to my cabbage, tomatoes, and because I didn't get adjectives of my potatoes out of the ground, next spring I have a new plant growing. So it's really not a yes or no answer, except they are classified as annuals.