Look to ensure a distance
11.7 inches (30.0 cm) between seeds when sowing - bury at a depth of at least
0.47 inches (1.2 cm) deep. Soil temperature should be kept higher than
16°C / 61°F to ensure good germination.
By our calculations, you should look at sowing Diamant about 14 days after your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Diamant is a tender plant.