GARDENING: Cannas are a colourful and exotic addition

My two Cannas hardening off in the greenhouse.
My two Cannas hardening off in the greenhouse.

I’VE always wanted to grow Cannas – they’re exotic, with big, dark leaves and blousy flowers – and after my visit to RHS Harlow Carr in February, I bought two in the plant centre.

They’re not named, but have very dark purple foliage and red flowers – they can reach 6ft tall.

As they’re tender perennials, I started them into growth in the conservatory. They will be planted out next week when fully hardened off (weather permitting) in a large tub with Dahlia Bishops’ Children.

Cannas can be grown in borders, but they’ll do better in big containers in NE England – somewhere hot, sheltered and sunny.

You can buy them now ready-potted in garden centres/nurseries, but it’s cheaper to buy the rhizomes (big fleshy roots) in spring, treating them like Dahlias.

Start them into growth in spring by planting in 20cm (8in) pots using multi-purpose compost, just covering them with compost, leaving any young shoots exposed.

Water sparingly at first and keep them at a temperature of 10-16°C (50-61°F).

Choose a container at least 30cm (1ft) wide, fill with John Innes No. 3 loam-based compost, with added controlled-release fertiliser. Plant the rhizomes 10cm (4in) deep.


• Give plenty of water in dry spells.

• Apply a liquid fertiliser in midsummer.

• Deadhead to encourage continued flowering. When a flower spike has no more buds, prune it down to the next side shoot.

• Stake clumps in exposed positions.

• Under glass, grow in full light but shade from hot sun.


• Move pot-grown specimens to a frost-free place, or lift the rhizomes once the top growth begins to wither in autumn.

• Cut down the foliage and stems to about 15cm (6in).

• Remove surplus soil, dry and then store in trays in barely-damp wood vermiculite or multi-purpose compost.

• Place in a frost-free position for the winter. Little, if any, watering should be necessary.