Sow at a depth of approx.
0.47 inches (1.2 cm) and aim for a distance of at least
3.12 inches (8.0 cm) between Cabbage plants. Soil temperature should be kept higher than
4°C / 39°F to ensure good germination.
By our calculations, you should look at sowing Derby Day about 45 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Derby Day is a hardy plant.