By our calculations, you should look at sowing Golden Spartan about 91 days before your last frost date.
Sow under glass in February for an early crop, or March-April for a main crop. They are not frost-hardy – plant outdoors May-June, 23cm (9") apart in each direction. Harvest July to mid-November. No earthing up required.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Golden Spartan is a tender plant.