I live in Zone 6 (Charleston, WV) and have bought some primroses. While I know there is a chance of a quick snow storm which can occur during the night, melt next day since the ground is warm. Could I go ahead and plant the primroses or should I hold until the snow chance is zero?
I would say that planting in your zone now would depend on a couple of things. My first thought is that if you purchased one of the fancy hybrid primroses and it was not kept outside when you purchased it, wait until all chance of frost is gone before you plant it. If you purchased it from a nursery that kept it outside, it should be fine to plant now when the soil is workable. These tend to be short lived plants, living 3 to 6 years.
If you purchased a candelabra type and it was grown and kept outside, then it should be fine to plant it outside once the soil can be worked.