A full sun position will ensure your plant thrives and remember to water moderately. Keep in mind when planting that Grand Duke is thought of as very hardy, so this plant will tend to survive through freezing conditions.
Growing Grand Duke from seed
By our calculations, you should look at sowing Grand Duke about 35 days before your last frost date.
Transplanting Grand Duke
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Grand Duke is a very hardy plant.