he easiest way to propagate rose campion is by seed, as it readily self-seeds, but you can also take basal cuttings in late spring; simply collect seeds from the spent flowers, sow them directly in the ground in late winter or early spring, and allow them to naturally germinate, thinning out seedlings as needed; to control propagation, collect seeds and sow them deliberately in a desired location. 

Key points about propagating rose campion:

Seed propagation:

Self-seeding: Rose campion readily self-seeds, so you can leave spent flowers on the plant to drop seeds naturally. 

Seed collection: If you want to control where the plants grow, collect seeds from the spent flower heads and store them for later sowing. 

Sowing time: Sow seeds in late winter or early spring, either directly in the ground or in pots. 

Cold stratification: Rose campion seeds benefit from a cold period (stratification) to germinate well, so consider winter sowing outdoors. 

Cutting propagation:

Timing: Take basal cuttings in late spring. 

Cutting selection: Choose healthy, young stems with a few leaves. 

Rooting medium: Plant cuttings in a well-draining potting mix and keep moist. 

Rooting hormone: Dip the cut ends in rooting hormone to encourage root development. 

Important considerations:

Thinning seedlings: If propagating from seed, thin out seedlings once they are large enough to handle to avoid overcrowding. 

Location: Rose campion thrives in full sun and well-drained soil. 

Potential invasiveness: Be mindful that rose campion can become invasive due to its prolific self-seeding nature, so manage its spread by removing unwanted seedlings.