Sow at a depth of approx.
0.25 inches (0.635 cm) and aim for a distance of at least
11.9 inches (30.5 cm) between Common yarrow plants. For optimal germination, soil temperature should be a minimum of
18°C / 64°F.
By our calculations, you should look at sowing Sue's Pink about 49 days before your last frost date.
Sue's Pink is hardy, so ensure you wait until all danger of frost has passed in your area before considering planting outside.