Keep in mind when planting that Guelph Millenium is thought of as hardy, so this plant will survive close to or on freezing temperatures.
Soil temperature should be kept higher than
21°C / 70°F to ensure good germination.
By our calculations, you should look at sowing Guelph Millenium about 90 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Guelph Millenium is a hardy plant.