Hardy water lily

Hardy water lily: how do you recognise it?

Habit

Floating leaves and flowers from a rhizome on the bottom. One plant spreads to about 1.2 m.

Leaves

Round and glossy, up to about 20–25 cm across, with a deep notch to the stalk. Green, sometimes flushed brown as they unfurl.

Flowers

Cup- to star-shaped, 10–15 cm across, floating on the water, from June to September.

Colour

White, pink or soft yellow with a yellow centre, depending on the cultivar.

Rhizome

Thick and fleshy. It grows horizontally in the planting basket and gets bigger every year.

Flowering: June–September · Plants: May–June

Why grow it?

• The queen of the pond: large flowers from June to September.
• The floating leaves cast shade, keep the water cooler and so help to hold back algae.
• Frogs, dragonflies and fish use the leaves for shelter and as a resting place.
• Fully hardy: it stays in the pond all year round.
• Little work: dividing it every few years is the main job.

Hardy water lily: where does it grow best?

• Full sun: at least six hours of sun a day for plenty of flowers.
• Still water: no fountain or waterfall nearby, as it dislikes splashing or moving water.
• A water depth of 40–80 cm above the basket.
• Heavy, clay soil in the planting basket; no potting compost, which floats up and clouds the water.
• Allow about 1–1.5 m² of water surface per plant, and keep part of the pond free of leaves.

Light

Sun

Soil type

Loam, clay or peat

Acidity

Acid or neutral

Moisture

Wet

Size

0.1 m tall, 1.2 m wide

Hardiness

Hardy (to -25 °C)

Goes well with

• Yellow flag iris: A sturdy marginal plant with yellow flowers in May–June.
• Marsh marigold: Golden-yellow flowers at the pond edge in early spring.
• Flowering rush: Pink flower heads in shallow water in summer.
• Hornwort: A submerged oxygenator that helps keep the water clear.
• Water forget-me-not: Small light blue flowers in the shallow margin.

Hardy water lily: when and how to plant it?

Plant in May–June.

1. Plant in May–June, once the water has warmed up.
2. Use a roomy planting basket at least 30–40 cm wide, lined with hessian or pond fleece and filled with heavy clay soil.
3. Set the rhizome at an angle in the soil with the growing point just showing, and top with a layer of gravel so the soil is not stirred up.
4. Stand the basket in shallower water at first, so the leaves reach the surface; prop it up on a few bricks if need be.
5. Lower the basket in stages over a few weeks to 40–80 cm, each time the leaves reach the surface.

Care

Tidying

Remove yellow leaves and faded flowers regularly, so they do not rot in the pond.

Feeding

In April–May, push a few aquatic plant fertiliser tablets deep into the soil in the basket. Never scatter fertiliser loose in the water: it feeds algae.

Space

Keep at least a third of the water surface free of leaves, for light and oxygen in the pond.

Dividing

Lift the basket every three to five years and divide the rhizome, especially when the leaves start standing up out of the water.

Tip: Place the water lily as far as possible from a fountain or waterfall: it flowers best in calm, still water. Remove old leaves and faded flowers regularly and the water will stay clear.

Hardy water lily: when to prune it?

When: No real pruning is needed. From June to October, regularly clear away old leaves and faded flowers.

How:

• Cut yellow leaves and faded flowers off as low as possible, with long-handled scissors or a pond knife.
• In autumn, clear away most of the dying leaves so they do not rot on the bottom.
• Cut off leaves that stand up out of the water: they are a sign of an overcrowded basket.

Pruning calendar and basic rules

Propagation

Division

Lift the basket every three to five years in May–June. Cut the rhizome into 10–15 cm pieces, each with a growing point and some roots, and replant them in a basket of fresh clay soil.

Hardy water lily: how does it get through the winter?

Hardy to −25 °C.

• Fully hardy, to about −25 °C. At 40–80 cm deep the rhizome does not freeze.
• Simply leave the basket where it is in the pond.
• In prolonged frost, keep a hole open in the ice with a pond heater or ice preventer, especially if there are fish. Never smash the ice.
• In a small, shallow pond or a tub the rhizome may freeze: move the basket to the deepest point for the winter.

Diseases and pests

• Water lily aphid: Dark aphids on the leaves and flowers. Hose them off the leaves into the water, where fish will eat them.
• Water lily beetle: Small beetles and their larvae eat grooves and holes in the leaves. Remove affected leaves and hose the larvae into the water.
• Leaves standing up: The basket is overcrowded and the rhizome too big. Lift the basket and divide the plant.
• Few flowers: Too little sun, too deep, disturbed water or an exhausted basket. Move it to a sunnier or shallower spot and add fertiliser tablets.
• Leaf spot: Brown or rotting patches on the leaves, especially in hot summers. Cut off affected leaves straight away.

Through the year

• April: Push fertiliser tablets into the basket. The first leaves appear.
• May: Plant or divide. Stand the basket in shallow water at first.
• June: Lower the basket. First flowers.
• July: Flowering. Remove faded flowers and yellow leaves.
• August: Flowering. Watch for aphids and water lily beetle.
• September: Last flowers. Clear away old leaves.
• October: Clear away dying leaves. Put a net over the pond to catch falling leaves.
• December: Rest. In frost, keep a hole open in the ice.

Did you know?

• Claude Monet bought water lilies from the Latour-Marliac nursery for his pond at Giverny, and painted them countless times.
• Each flower opens in the morning and closes in the evening for a few days in a row before it fades.
• The Latour-Marliac nursery at Le Temple-sur-Lot, in south-western France, still exists today.