Look to ensure a distance
3.96 feet (1.22 metres) between seeds when sowing - bury at a depth of at least
0.25 inches (0.64 cm) deep.
By our calculations, you should look at sowing Explorer rose 'Henry Kelsey' about 35 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Explorer rose 'Henry Kelsey' is a hardy plant.