Keep in mind when planting that Swwet Purple is thought of as hardy, so Swwet Purple will tend to go dormant or grow slowly over the winter months.
Soil temperature should be kept higher than
21°C / 70°F to ensure good germination.
By our calculations, you should look at sowing Swwet Purple about 90 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Swwet Purple is a hardy plant.