Look to ensure a distance
0.5 inches (1.27 cm) between seeds when sowing - bury at a depth of at least
0.12 inches (0.3 cm) deep. Soil temperature should be kept higher than
10°C / 50°F to ensure good germination.
By our calculations, you should look at sowing Sweet Petra Dark about 20 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Sweet Petra Dark is a tender plant.