I would like to save seeds from turnips but don't know much about when to plant them for saving seeds.
Do I sow them in the spring and let them bolt to save seeds from?

We plant turnips in the fall here for eating.

If you have a rare turnip, saving seed is pretty easy. For common turnips probably not worth the space and effort. Fall planted turnips will bolt in the spring. Just let the the seed pods dry somewhat on the plants, pul the plant and let it complete drying i a sheltered space, Strip out the seeds and you are in business. In turnips will not survive the winter in your climate, Then spring planting will work. It just ties up space in the growing season.

Thanks for replying farmerdill. They did winter over for the first time ever probably due to the location selected for them this time.

How warm does it need to get before they will bolt?
Space isn't an issue if I decide to do a spring planting to get seeds for a fall planting. My husband wants that spot for sweet potatoes and I'm trying to convince him to leave the turnips until they set seed since sweet potatoes can't be planted until late May or early June here.

Over wintered turnips will bloom with early flowers like tulips of daffodils.

Oh good won't be long then as the daffodils and tulips are both up here.

Thank you so much for the help I appreciate it