Try to aim for a seed spacing of at least
2.92 feet (90.0 cm) and sow at a depth of around
0.99 inches (2.54 cm). Soil temperature should be kept higher than
15°C / 59°F to ensure good germination.
By our calculations, you should look at sowing Onyx about 21 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Onyx is a tender plant.
By our calculations, you should look at planting out Onyx about 0 days after your last frost date.