I wrote recently about watering during an extended hot spell, and while working today I was…
They will thrive in fertile, well-drained soil with full sun. Cut back hard after flowering.
You can propagate by seed in autumn or spring or by softwood or semi-ripe cuttings of non-flowering shoots in mid-summer. Propagate cultivars by cuttings.
Pests, diseases or disorders
May be damaged by slugs and snails and powdery mildew.