Aim to sow
0.47 inches (1.2 cm) deep and try to ensure a gap of at least
3.12 inches (8.0 cm). Soil temperature should be kept higher than
4°C / 39°F to ensure good germination.
By our calculations, you should look at sowing Precoce De Louvriers about 45 days before your last frost date.
As Precoce De Louvriers is hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.