Aim to sow
0.25 inches (0.635 cm) deep and try to ensure a gap of at least
11.9 inches (30.5 cm). Soil temperature should be kept higher than
18°C / 64°F to ensure good germination.
By our calculations, you should look at sowing Summer Berries about 49 days before your last frost date.
As Summer Berries is hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.