Merck dahlia

Plant tubers 10-15cm deep in fertile, humus-rich, well-drained soil, in full sun. Cut back to near ground level in mid-autumn. In mild areas, and on well-drained soils, leave the tubers in the ground and protect with a deep, organic mulch. In colder areas, or on heavy soils, lift and store the tubers and replant in late spring after all danger of frost has passed. See dahlia cultivation

Deadhead to prolong flowering

Propagate by basal softwood cuttings taken in spring from shoots from stored tubers, or divide clumps of tubers ensuring that each division has a viable bud

May be susceptible to aphids, capsid bug, earwigs, caterpillars, slugs, glasshouse red spider mite and onion thrips

May be susceptible to powdery mildews, dahlia mosaic virus, cucumber mosaic virus, tomato spotted wilt virus, storage rots, leafy gall, crown gall, dahlia smut, grey moulds, fungal leaf spot, phytophthora, sclerotinia and verticillium wilts