Keep in mind when planting that Prince of Silver is thought of as very hardy, so this plant will tend to survive through freezing conditions.
Try to ensure a gap of at least
4.68 inches (12.0 cm) when sowing to prevent overcrowding your seedlings.
By our calculations, you should look at sowing Prince of Silver about 63 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Prince of Silver is a very hardy plant.