Aim to sow
0.58 inches (1.5 cm) deep and try to ensure a gap of at least
0.98 inches (2.5 cm). Soil temperature should be kept higher than
13°C / 55°F to ensure good germination.
By our calculations, you should look at sowing All american about 130 days after your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as All american is a hardy plant.