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 Persian about 14 days after your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Persian is a tender plant.