Sow at a depth of approx.
0.04 inches (0.1 cm) and aim for a distance of at least
5.85 inches (15.0 cm) between Heartsease plants. Soil temperature should be kept higher than
15°C / 59°F to ensure good germination.
By our calculations, you should look at sowing Bowle's Black about 90 days before your last frost date.