When to Plant Hardy Primrose Outside
When can I safely plant primrose outdoors?
Certified GKH Gardening Expert
If they are indoor grown primroses, I would wait until the chance of frost has passed. While they may be hardy, they will not have developed the hardening chemicals that outdoor plants produce to protect them from the cold and would be susceptible to frost. Here is more information on growing primrose plants: https://www.gardeningknowhow.com/ornamental/flowers/primrose/growing-primrose-primrose-plants-in-your-garden.htm