Water soldier

Water soldier: how do you recognise it?

Habit

Floating rosette about 30 cm tall and 40 cm wide, partly under and partly above the water; sometimes loosely rooted in the bottom.

Leaves

Stiff, narrow and sword-shaped, 15–40 cm long, dark green and brittle, with sharp, spiny teeth along the edge.

Flowers

White, 3–4 cm across, with three petals, emerging from a sheath between the leaves, from June to August. Male and female flowers grow on separate plants.

Roots

Long, unbranched roots that hang freely in the water or grow into the mud.

Runners

In summer it makes runners with young rosettes, so it multiplies quickly.

Pond zone

Deep water: floating, from 40 cm deep.

Flowering: June–August · Plants: May–July

Why grow it?

• An unusual plant with spiky rosettes that rise and sink in the water: different every season.
• White flowers with three petals, from June to August.
• Tadpoles, newts, small fish and dragonfly larvae shelter among the rosettes.
• Shades the water and takes up nutrients, which helps to keep the water clear.
• Native, hardy and grown without basket or soil: you simply lay it on the water.

Water soldier: where does it grow best?

• Sun to partial shade.
• Clear, still water that is not too rich, neutral to alkaline.
• At least 40 cm of water, so the plant can lie on the bottom under the ice in winter; a bottom of loam, clay or peat.
• Do not let it cover more than a third of the water surface, so there is open water left.

Light

Sun and partial shade

Soil type

Loam, clay or peat

Acidity

Neutral or chalky

Moisture

Wet

Size

0.3 m tall, 0.4 m wide

Hardiness

Hardy (to -25 °C)

Goes well with

• Frogbit: A small related floating plant with white flowers, for the same quiet spot.
• Rigid hornwort: A submerged oxygenator that helps keep the water clear.
• Water violet: White to pale lilac flowers above the water in May–June, in clear, still water.
• Water lily: Large floating leaves and flowers in the deepest part of the pond.

Water soldier: when and how to plant it?

Plant in May–July.

1. Put it in the pond from May to July, when the water is warm and the plant is floating.
2. No basket or soil is needed: simply lay the rosette on the water in a spot at least 40 cm deep.
3. Rinse the plant first in a bucket of pond water, so you do not bring in snails or eggs from other ponds.
4. Start with one to three rosettes: it multiplies quickly.
5. Do not worry if it sinks a little at first: it usually comes back up after a few days or weeks.

Care

Water

Top up the pond with rainwater when the level drops; it needs at least 40 cm of water.

Feeding

Never: it likes clear water that is not too rich.

Thinning

In summer lift surplus rosettes out with a pond rake or net, so there is open water left.

Gloves

Always wear sturdy gloves: the toothed leaf edges cut your hands.

Tidying

In autumn remove loose dead leaves that stay floating.

Tip: Lay it in the pond in a spot at least 40 cm deep and be patient in spring: it is still lying on the bottom then and only rises when the water is warm enough.

Water soldier: when to prune it?

When: Water soldier is not pruned. In summer you thin it out, and in autumn you remove dead leaves.

How:

• In July–August lift surplus young rosettes out of the water; keep the best ones.
• Cut or pull away loose brown leaves; leave healthy rosettes alone.
• Leave whatever you take out of the water on the bank for a day, so small creatures can return to the pond.

Caution: Always work with gloves: the leaf edges are sharply toothed.

Pruning calendar and basic rules

Propagation

Offsets

In summer it forms young rosettes on runners. Cut them free in July–September once they have their own ring of roots and lay them in another pond at least 40 cm deep.

Water soldier: how does it get through the winter?

Hardy to −25 °C.

• Hardy, to about −25 °C: in autumn it sinks to the bottom and overwinters under the ice.
• So the pond must be at least 40 cm deep; in shallow water it freezes into the ice and dies.
• In a tub or mini pond: put a few rosettes in a bucket of water in a cool, frost-free place in autumn.
• During long frosts keep a hole open in the ice of a pond with fish, without hitting the ice.

Diseases and pests

• Not rising: In April it is still on the bottom: that is normal. It only rises when the water warms up, sometimes not until May or June.
• Spreading too much: The rosettes cover the whole water surface. Thin out every summer until at most a third of the water is covered.
• Brown or rotting rosettes: Often water that is too rich, murky or warm. Use no fertiliser, top up with rainwater and make sure there is enough depth and some oxygenators.
• Cuts: The toothed leaf edges cut when you thin it out. Always wear sturdy gloves.

Through the year

• April: The rosettes are still on the bottom or slowly rising.
• May: It rises. Plant: lay new rosettes on the water.
• June: First white flowers. Plant.
• July: In flower. Thin out wearing gloves. Planting is still possible.
• August: Last flowers. Remove surplus rosettes.
• September: Detach young rosettes and pass them on.
• October: The rosettes sink to the bottom. Remove dead leaves.
• December: Resting on the bottom. Keep a hole in the ice during long frosts.

Did you know?

• In the Netherlands the rare green hawker, a dragonfly, lays its eggs almost only in the leaves of water soldier.
• The black tern, a marsh bird, likes to build its nest on floating mats of water soldier.
• In Canada, where it is not native, it has escaped into the wild and spreads rampantly in some lakes and canals.