Cover with a fine sprinkling of compost/vermiculite, do not exclude light.
Soil temperature should be kept higher than 15°C / 59°F to ensure good germination.By our calculations, you should look at sowing Lilac Frost about 63 days before your last frost date.
Acclimatise over 10-15 days prior to transplant.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Lilac Frost is a hardy plant.