Look to ensure a distance
11.7 inches (30.0 cm) 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 Giant Dahlia Flowered Deep Rose about 21 days before your last frost date.
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Giant Dahlia Flowered Deep Rose is a tender plant.