Keep in mind when planting that Arctic Mix is thought of as hardy, so this plant will survive close to or on freezing temperatures. Ensure your soil is sandy, loamy and clay and has a ph of between 5.6 and 6.0 as Common Primrose is a weakly acidic soil loving plant.
By our calculations, you should look at sowing Arctic Mix about 105 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Arctic Mix is a hardy plant.