Look to ensure a distance
7.8 inches (20.0 cm) between seeds when sowing - bury at a depth of at least
1.17 inches (3.0 cm) deep. Soil temperature should be kept higher than
21°C / 70°F to ensure good germination.
By our calculations, you should look at sowing Silver Platinum about 14 days after your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Silver Platinum is a tender plant.