Keep in mind when planting that Wisley Pink is thought of as half hardy, so remember to protect this plant from frosts and low temperatures.
Try to aim for a seed spacing of at least
11.7 inches (30.0 cm) and sow at a depth of around
0.04 inches (0.1 cm). Soil temperature should be kept higher than
18°C / 64°F to ensure good germination.
By our calculations, you should look at sowing Wisley Pink about 56 days before your last frost date.
As Wisley Pink is half hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.