Try to aim for a seed spacing of at least
11.7 inches (30.0 cm) and sow at a depth of around
0.47 inches (1.2 cm). Soil temperature should be kept higher than
16°C / 61°F to ensure good germination.
By our calculations, you should look at sowing Diva non-hybrid slicing about 14 days after your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Diva non-hybrid slicing is a tender plant.