Look to ensure a distance
11.7 inches (30.0 cm) between German seeds when sowing to make sure your seedlings have enough space. Soil temperature should be kept higher than
21°C / 70°F to ensure good germination.
By our calculations, you should look at sowing German about 42 days before your last frost date.
As German is hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.