water canna 'Erebus'

In summer, water cannas (often bred from Canna glauca) can be placed in containers in ponds with no more than 15cm (6in) of water over the roots. They are also suitable for well-watered borders or conservatories where potted plants can be stood in deep saucers of water. Before autumn frosts, bring plants from outdoors into a frost-free greenhouse or conservatory. Keep the pots moist but not saturated. In April, increase temperatures and plant the sprouted plants out in late May when the risk of frost has passed. Further canna cultivation advice

Deadhead to promote continued flowering. Leave to dieback in autumn

Propagate by seed at 21°C (70°F) in spring or autumn. Soak seed in warm water before sowing. Cultivars may not come true from seed. Propagate by division in early spring

Glasshouse red spider mite, slugs and caterpillars may be troublesome

Canna can be susceptible to a virus