Sow
0.25 inches (0.64 cm) deep with a guideline distance of
3.96 feet (1.22 metres).
By our calculations, you should look at sowing Honorine de Brabant about 35 days before your last frost date.
As Honorine de Brabant is hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.