Keep in mind when planting that William Guinness 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 Guinness 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 Guinness is a hardy plant.
The species name vulgaris is from the Latin vulgus (“the multitude, the masses”) + -āris, and means “common”, “usual”, or “commonly known” .