Try to aim for a seed spacing of at least
1.88 feet (58.0 cm) and sow at a depth of around
0.5 inches (1.27 cm). Soil temperature should be kept higher than
21°C / 70°F to ensure good germination.
By our calculations, you should look at sowing Heart of Gold about 14 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Heart of Gold is a hardy plant.