Keep in mind when planting that Cannington John is thought of as half hardy, so although it can survive a small mild cold snap, it is wise to ensure that this plant is protected from frost damage.
Sow
0.04 inches (0.1 cm) deep with a guideline distance of
11.7 inches (30.0 cm). Soil temperature should be kept higher than
18°C / 64°F to ensure good germination.
By our calculations, you should look at sowing Cannington John about 56 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Cannington John is a half hardy plant.