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Cannas

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  • Canna x chemanii, Equisetum (barred horsetail) and Geranium White Ness

Truly exotic flowers and foliage

I love cannas – such big, colourful leaves and showy flowers – and after a visit to RHS Harlow Carr, I bought two in the plant centre. They are not named varieties (which I found quite surprising) but have very dark purple foliage and burnt orange flowers.

Turns out they were a good place to start and have been very easy to keep going from one season to the next. Once you grow one, it’s difficult to stop! There are so many varieties with vivid foliage and showy flowers. They also grow to varying heights, from the 90cm Tropicanna range to Wyoming, which can reach 2.3m.

If you’re a fan of gentle, calming gardens, cannas may not be for you. However, if you want to create a jungle effect or a make-believe holiday hideaway, these are the plants for you. If you want a good basic collection, Farmer Gracy has a wide selection.

As they’re tender perennials, I start them into growth in the conservatory. They’re all in pots, so I move them into the unheated greenhouse in April, finally hardening them off outside in May.

Cannas can be grown in borders, but not in my heavy soil. However, my raised beds are ideal, with well-drained, rich soil. They don’t like going short of water, so I add water gel capsules to help them along.

Creating more plants – try growing cannas from seed

If you want to increase your stock, they’re one of the easiest plants to propagate for beginners. My original two rhizomes have been divided into about 12 plants now. For more information on how to do this, visit my post on Canna Tropicanna here.

You can also grow plants from seed, a very cost-effective option. I did this for the first time in 2023 and they were much easier than I thought, costing a mere 12.4p per plant! Read more about growing Cannas from seed.

Cannas
Canna standing out against a backdrop of a golden hop, holly, Shasta daisies and Echiums

Potted guide

Potted guide: Cannas

  • Start the rhizomes (big fleshy roots) into growth in spring by planting in pots just big enough for them. This way, you save on expensive compost.
  • If they are already in pots, get rid of most of the old compost.
  • Use good multi-purpose compost and just cover the rhizomes, leaving any young shoots exposed.
  • Water sparingly at first and keep at a temperature of 10-16°C. Increase watering as plants grow and gradually harden them off before planting out after the last frost.
  • When they go outside, move them to large containers at least 30cm wide, filled with John Innes No. 3 loam-based compost, with added controlled-release fertiliser. You can also plant them in raised beds or borders with well-drained, rich soil.
  • 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 – another one will form.
  • Stake clumps in exposed positions.
  • You can grow them in cool conservatories in summer, in full light but shade plants from the hot sun in colder areas.
Canna
I keep my Canna dry in their pots over winter and they get an early start in the conservatory
  • Tropicanna: red, pink, yellow, gold, and green striped foliage, tangerine flowers, 1.5m.
  • Striata: golden-striped green leaves, orange flowers, 1.9m.
  • Tropicanna Black: purple-black leaves, scarlet flowers, 1.5m.
  • Phasion: striped leaves, orange flowers, 1.6m.
  • Tropicanna Gold: green/gold striped foliage, orange flowers edged in yellow.
  • Picasso: green/blue-ish leaves, yellow flowers spotted with red, 1.5m.
  • Wyoming: bronze leaves, orange flowers, 2.3m.
  • Durban: pink/green/red foliage, orange flowers, 90cm.
  • Monique: streaky copper, cerise and plum-red leaves, salmon-pink flowers, 90cm.
  • Stuttgart: cream/green variegation, peachy-orange flowers, 90cm.
  • Pretoria: green/yellow leaves, orange flowers, 160cm.
Geraniums, cannas, dahlias
Geraniums, cannas and dahlias in the greenhouse in April

Overwintering cannas

  • Move pot-grown plants to a frost-free place, or lift the rhizomes from borders once the top growth begins to wither in autumn (just like dahlias).
  • Cut down the foliage and stems to about 15cm.
  • Remove any surplus soil, dry the rhizomes and then store them in trays of barely-damp vermiculite or multi-purpose compost.
  • Little, if any, watering should be necessary.
  • I find the pot overwintering method by far the easiest and pot up any plants that have been in raised beds for the winter.
  • By January, in sunny weather, rhizomes start sprouting new shoots.

Cannas page updated 2023