Canna lily

Canna lily: how do you recognise it?

Habit

Upright clumps about 1.2 m tall and 50 cm wide, with sturdy stems.

Leaves

Large, broad and paddle-shaped, up to 50 cm long; green, bronze, purple or striped with yellow or pink.

Flowers

Spikes of irregular, gladiolus-like flowers at the top of the stems, from July to October.

Colour

Red, orange, yellow, pink or cream, sometimes spotted or with a coloured edge.

Rhizome

Thick, fleshy and branched, with eyes from which new shoots grow. Not hardy.

Flowering: July–October · Plants: May–June · Pruning: October–November

Why grow it?

• Its large leaves create an instant tropical feel, even when it is not in flower.
• Flowers for a long time, from July until the first frost in October or November.
• Cultivars with bronze, purple or striped leaves are eye-catching all summer.
• Ideal in a large pot on a sunny patio or as the centrepiece of a border.
• Grows fast: from a rhizome in April to a plant over a metre tall in August.

Canna lily: where does it grow best?

• Full sun and a warm spot: the more sun, the better it flowers.
• Rich, humus-rich soil: sand, loam or clay, neutral to chalky. Dig in plenty of compost or well-rotted manure beforehand.
• Moist to wet: it needs a lot of water in summer and copes with wet soil better than with drought.
• Sheltered from strong wind, which tears the large leaves. Allow 40–60 cm between plants.

Light

Sun

Soil type

Sand, loam or clay

Acidity

Neutral or chalky

Moisture

Normal or wet

Size

1.2 m tall, 0.5 m wide

Hardiness

Frost tender: lift the bulbs or tubers before the frost and store them frost-free

Goes well with

• Dahlia: Flowers at the same time and needs the same care, including lifting.
• Purpletop vervain: Airy purple flower heads that float between the large canna leaves.
• Hardy banana: Even bigger leaves for a true tropical border.
• Fountain grass: Soft plumes as a light contrast to the sturdy canna.

Canna lily: when and how to plant it?

Plant in May–June.

1. Start the rhizomes indoors in April: place them in a pot of compost, 5 cm deep, in a light spot at 15–20 °C.
2. Keep the compost slightly moist until the first shoots appear, then water more.
3. From mid-May, harden the plants off outdoors during the day and plant them out in late May or June, once the risk of frost has passed.
4. Dig a generous hole with compost and set the plant at the same depth as in the pot, 40–60 cm apart.
5. Water well straight away and mulch around the base.
6. In a pot: choose at least 30–40 cm across, with rich potting compost and a drainage hole.

Care

Watering

Water generously; plants in pots need water every day in hot, dry spells. The soil must never dry out.

Feeding

From June to late August, liquid feed for flowering plants every two weeks, or a generous helping of compost or organic fertiliser in spring.

Mulching

A layer of compost or grass clippings keeps the soil moist and feeds the plant.

Spent flowers

Cut faded spikes back to just above the next leaf or side shoot: a new spike will form there.

Repotting

In a pot, replant every spring in fresh compost; divide rhizomes that have grown too large.

Tip: Start the rhizome indoors in a pot in April and plant out in late May in rich soil. Give plenty of water and feed for large leaves and flowers.

Canna lily: when to prune it?

Pruning months: October–November.

When: After the first frost, in October or November, when the leaves blacken, cut the stems back before lifting the rhizomes.

How:

• Cut all stems back to 10–15 cm above the ground.
• Carefully dig up the rhizome and shake off the soil.
• In summer, cut off faded flower spikes just above the next leaf.
• Remove damaged or torn leaves at the base.

Caution: Do not lift the rhizomes too late: a few nights of light frost on the leaves do no harm, but frozen rhizomes rot.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In April, when starting them into growth, cut the rhizome with a sharp knife into pieces with at least one or two eyes each. Let the cuts dry for a day before potting.

Seed

The seeds are rock-hard. File them lightly or soak them for 24 hours in lukewarm water and sow in February–March at 20–25 °C. Seedlings rarely resemble the parent.

Canna lily: how does it get through the winter?

Hardy to 0 °C: protect in harsh winters.

• Not hardy: the rhizome cannot survive frost. In Belgium, lift it every autumn.
• Let the lifted rhizomes dry for a few days in a frost-free place and store them in a box of slightly moist compost, sand or wood fibre.
• Keep them cool and frost-free, at about 5–10 °C, for example in a cellar or garage.
• Plants in pots: move the whole pot to a frost-free place and keep the compost almost dry until April.

Diseases and pests

• Slugs: Eat holes in the young shoots in May and June. Only plant out sturdy plants and pick off slugs in the evening.
• Torn leaves: Strong wind shreds the large leaves. Choose a sheltered spot, for example against a hedge or wall.
• Virus: Yellow streaks, mottling or distorted leaves point to a virus. There is no cure: discard the plant with its rhizome and buy healthy stock.
• Winter rot: Storage that is too wet or too warm makes the rhizomes rot. Check them in winter and cut away soft parts.
• Poor flowering: Too little sun, water or food. Give it the sunniest spot and feed regularly.

Through the year

• January: Check stored rhizomes for rot.
• March: Inspect the rhizomes. Sow indoors at 20–25 °C.
• April: Divide the rhizomes and start them in pots indoors.
• May: Harden off outdoors during the day. Plant out in late May, once frost is no longer expected.
• June: Plant out. Water and feed generously.
• July: First flowers. Feed every two weeks.
• August: Full flower. Cut off faded spikes. Water a lot.
• September: Flowering. Stop feeding.
• October: After the first frost, cut back to 10–15 cm and lift.
• November: Dry the rhizomes and store them frost-free.

Did you know?

• What look like petals on a canna are largely modified stamens. Only one stamen still produces real pollen.
• The English name ‘Indian shot’ refers to the round, rock-hard seeds, which are said to have been used as shot in the past.
• Despite the name ‘canna lily’, it is not a lily: the canna has a family of its own and is related to bananas and ginger.