Keep in mind when planting that Christa Barlow is thought of as hardy, so this plant will grow or become dormant during the winter.
Soil temperature should be kept higher than
18°C / 64°F to ensure good germination.
By our calculations, you should look at sowing Christa Barlow about 56 days before your last frost date.
As Christa Barlow is hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.