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 Oranges & Lemons about 35 days before your last frost date.
As Oranges & Lemons is hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.