Try to aim for a seed spacing of at least
2.28 feet (70.0 cm) and sow at a depth of around
1.17 inches (3.0 cm). Soil temperature should be kept higher than
15°C / 59°F to ensure good germination.
By our calculations, you should look at sowing Cobnut about 10 days before your last frost date.
As Cobnut is tender, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.