Look to ensure a distance
5.85 inches (15.0 cm) between seeds when sowing - bury at a depth of at least
0.49 inches (1.25 cm) deep. Soil temperature should be kept higher than
5°C / 41°F to ensure good germination.
By our calculations, you should look at sowing Butterhead marvel of four seasons about 53 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Butterhead marvel of four seasons is a tender plant.