Keep in mind when planting that White Star is thought of as very hardy, so this plant will tend to survive through freezing conditions.
Try to ensure a gap of at least
11.89 inches (30.48 cm) when sowing to prevent overcrowding your seedlings.
By our calculations, you should look at sowing White Star about 56 days before your last frost date.
As White Star is very hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.