Try to aim for a seed spacing of at least
0.98 inches (2.5 cm) and sow at a depth of around
0.47 inches (1.2 cm). Soil temperature should be kept higher than
16°C / 61°F to ensure good germination.
By our calculations, you should look at sowing Guernsey about 15 days after your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Guernsey is a half hardy plant.