visionspictures.com giant dahlia, imperial dahlia
A tuberous, strongly upright, species dahlia, forming large clumps to about 3m in height. Produces multi-branching bamboo-like stems carrying bronze green serrated leaves and large, single yellow centred, lilac-purple flowers through summer into autumn
2.5-4 metres
1.5-2.5 metres
| Season | Stem | Flower | Foliage | Fruit |
|---|---|---|---|---|
| Spring | ||||
| Summer | ||||
| Autumn | ||||
| Winter |
Grow in fertile, humus-rich, moist but well-drained soil, in full sun. Pinch out growing tips to encourage bushy plants and stake taller dahlias, see staking perennials. Water in dry periods if needed. Lift and store tubers in autumn to replant, or use as a source of cuttings, in spring. See dahlia cultivation, and our video How to plant dahlia tubers and care tips
Propagate by softwood cuttings taken in spring from shoots from stored tubers, or divide the tubers ensuring each division has a viable bud
Deadhead spent flowers to encourage further flowering. Cut back to near ground level in autumn, before lifting and storing for the winter
May be susceptible to aphids, leaf miners, glasshouse red spider mite and slugs. Earwigs sometimes damage blooms. Capsid bug and caterpillars are occasional pests
May be susceptible to Powdery mildews in dry conditions. In wet weather grey moulds and other fungal rots can be a problem. Fungal rots can also damage stored tubers. A virus may cause stunting, leaf markings and distortion