Answer: Some rose hips do contain viable seeds, but not all of them do. The only way you'll know is if you harvest and plant them. Early winter is the time to harvest the hips. Those that are on your plants now may or may not sprout. I think it's worth a try - if not, you can try again this coming winter.
To propagate, cut the hips off when they're fully colored, but before they shrivel. Bury them in trays of moist compost, outdoors in the cold. Frost is essential to germination, which is why a hard winter can result in a forest of seedlings around roses that are left unpruned. In late winter, sort out the hips and squeeze their contents into a bowl of water, where they'll either float or sink. Only the seeds that sink are fertile and worth planting. They should be sown in pots in a cold frame.
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