Keep in mind when planting that William Guiness Doubles is thought of as hardy, so this plant will survive close to or on freezing temperatures.
Soil temperature should be kept higher than
18°C / 64°F to ensure good germination.
By our calculations, you should look at sowing William Guiness Doubles about 56 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as William Guiness Doubles is a hardy plant.
William Guiness Doubles, Magpie Doubles