Try to aim for a seed spacing of at least
3.96 feet (1.22 metres) and sow at a depth of around
0.25 inches (0.64 cm).
By our calculations, you should look at sowing Keith Maughan about 35 days before your last frost date.
As Keith Maughan is hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.