This section is from the book "The Gardener's Monthly And Horticulturist V22", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
I think Primula rosea is quite as hardy as P. acaulis. I have some plants of it in an artificial bos, and although we have had five weeks hard frost without snow, and the plants were covered with a miniature glacier caused by the water freezing as it overflowed the ground, I find them quite uninjured, and each plant will produce a half dozen spikes at least. I think it would do well under your deep covering of snow.
Crocus odorus longifolius has kept blooming during the whole frost. I should not have thought the buds could have pushed through the frozen soil in the way they did. I have not been without Crocus bloom since October. C. Imperati is about to open; C. aurea will follow it closely. Saxifraga Bursereana is showing its scarlet buds and will soon be in bloom, - although our Snowdrops make little progress. "We get earlier spring flowers than we did in Shakespeare's time.