# Water soldier: a spiny native pond plant

> Water soldier (Stratiotes aloides): a native pond plant with spiny toothed leaves to 45 cm and white flowers from May to July. How to spot, plant and price it.

Canonical: https://tuinontwerp.app/en/blog/water-soldier-pond-plant
Last updated: 2026-09-28

*Stratiotes aloides*

![A floating cluster of water soldier in a garden pond in front of a wooden fence, in June, with narrow toothed leaf rosettes and a few small white flowers](https://tuinontwerp.app/images/blog/krabbenscheer-4d41cf0b.webp)

Published: 2026-09-28

Water soldier (Stratiotes aloides) is a native water plant that floats as a
spiny rosette in still water. Its narrow leaves have toothed edges. From May
to July the plant flowers white, with three petals. In winter the water
soldier sinks to the pond floor. Set it loose in a calm, sunny pond.

## Water soldier at a glance

| Feature | Water soldier |
| --- | --- |
| Height | 15 to 40 cm |
| Spread | 0.5 to 1 m |
| Full grown after | 5 to 10 years |
| Sun | Full sun to partial shade |
| Soil | None: floats loose in still water |
| Water | Plenty: lives in the pond |
| Maintenance | Low: sometimes remove rosettes |
| Flowers | May to July, white |
| For bees | Little: pollinated by flies, among others |
| Hay fever | Unknown |
| Leaves | Partly green: overwinters on the bottom |
| Hardy | Yes |
| Native | Yes |
| Poisonous | No, as far as known |
| Pricks or stings | Yes: spiny leaves |
| Price, young | About €3.25 to €4.99 per plant, loose |
| Price, grown | Not for sale |

- **Leaf**: all year
- **Flower**: May to July
- **Fruit**: no noticeable fruit

![A young water soldier rosette rising from still pond water, with narrow, pointed leaves whose edges are finely toothed](https://tuinontwerp.app/images/blog/krabbenscheer-leaf-cc1540f3.webp)
*Leaf*

![One open water soldier flower just above the water, with three broad white petals around yellow stamens, among toothed leaves](https://tuinontwerp.app/images/blog/krabbenscheer-bloom-a25e718d.webp)
*Flower*

## How do you recognise a water soldier?

Look at the leaf first. A rosette has many narrow leaves that taper slowly
to a sharp point. They grow up to 45 cm long. The edge is strongly toothed,
and each tooth carries a small forward-pointing spine. Above water the leaf
is grass green; below water it turns dark green to wine red.

The flower is about 4 cm wide, with three white petals. One plant carries
only male or only female flowers. The flowers come from a spathe, a sheath
in the leaf axil. From each spathe, a female plant produces one flower,
almost without a stalk. A male plant produces three to six stalked flowers
from one spathe, of which only one blooms at a time.

Water lettuce looks similar from a distance, since it also floats as a
rosette on the water. Its leaf is soft, light green and ribbed, with long
feathery roots underneath. Water lettuce also cannot survive frost. The
water soldier has stiff, narrow, spiny leaves and survives winter outdoors.

## Where does a water soldier grow best?

A water soldier wants shallow, still and nutrient-rich water in a sheltered
spot. In the wild the plant grows in water 50 cm to 2 m deep. The rosette
prefers full sun. Around midsummer that means more than six hours of direct
sunlight on the water. Partial shade also works, with three to six hours of
direct sunlight.

Here is where it goes wrong:

- **A pond with a pump, skimmer or fountain.** The rosettes drift loose.
  Moving water carries them away, sometimes into the pump.
- **A small pond you want to keep open.** New rosettes on the runners can
  fill a small water surface completely.

In January you usually see nothing of the water soldier at the surface.

In the app you place your own plot to scale, with the buildings around it.
On that plot you draw the pond between your terrace, your borders and the
fence. That way you see, before you start digging, how big the pond can
become.

## Planting and caring for a water soldier

A water soldier goes straight onto the water, never into soil. Set the
rosette loose, without a basket, pond soil or gravel. Choose a calm part of
the pond. Put a new plant into the water as soon as it arrives, so it does
not dry out.

Plan on about 5 plants per 2000 litres of water. Do not place them close
together. Each plant eventually needs half a metre to a full metre of
space. On the first day that looks like a lot of open water.

Watering is never needed, because the plant lives in the pond. Extra
feeding is not needed either, and neither is pruning.

## Water soldier problems and what to do

**The plant stays on the bottom.** In cold water a water soldier sometimes
sinks a little towards the bottom. If the rosette lies at less than 50 cm
deep, it grows and floats up again once the water warms. If the plant lies
deeper, move it to a shallower part of the pond.

**The new plant lies on its side.** Plants sent later in the season are
often top-heavy. It can take a few weeks before they float upright. Just
leave them be.

**The pond fills up.** Every spring, runners grow from the leaf axils, with
a young plantlet at the end. Remove the surplus rosettes and leave the
rest. Wear gloves while doing this, because the leaf edges prick. Never
throw what you remove into a ditch or pool: plant material from a pond
does not belong in natural water.

**No fruit appears.** That is normal. A colony often grows from a single
plant and is then entirely male or entirely female. Fruit is therefore
rarely seen, and it makes no difference to the pond.

## Which birds and insects use a water soldier?

The green hawker is a dragonfly strongly tied to the water soldier. The
female lays her eggs almost only in water soldier plants. The eggs also
overwinter there. The dragonfly flies from late June to late September,
with most sightings in August.

> **Did you know?**
>
> The green hawker's larva usually climbs out of the water by way of a water
> soldier. Above water, the dragonfly emerges from its skin. The empty
> larval skin stays behind on the leaf.

The black tern, a bird of marshes, builds its nest on floating plants,
preferably on water soldier. The sharp decline of the water soldier costs
that bird many nesting spots.

## Is a water soldier poisonous or edible?

The water soldier is not known to be poisonous. For a garden pond, no risk
is therefore known. No edible parts are known either. That the plant is
not known to be poisonous does not make it edible.

The photos on this page were made with AI, based on real photos and descriptions of this plant.

## Frequently asked questions

### How do you put a water soldier in a pond?

You set the plant loose on the water, without a basket or pond soil. Choose a calm spot with no pull from a pump or skimmer. In water less than 50 cm deep the plant grows well and floats up once the water warms.

### Why does a water soldier sink in autumn?

A water soldier overwinters on the bottom of the pond. Most of the leaf dies back then, but the stem stays alive. In spring the plant comes back up.

### How many water soldiers does a pond need?

Plan on about 5 plants per 2000 litres of water. After that, each plant makes new rosettes of its own through runners.

### Is a water soldier poisonous?

The water soldier is not known to be poisonous. No edible parts are known either.

### Is a water soldier a native plant?

Yes, the water soldier is originally native to the Netherlands. Since 1950 the species has declined sharply in the wild, by 50 to 75 percent.

## Sources

- [Duistermaat, Sparrius & Denters, Standaardlijst van de Nederlandse flora 2020 (Gorteria 43)](https://natuurtijdschriften.nl/pub/1019223)
- [NDFF Verspreidingsatlas — Stratiotes aloides](https://www.verspreidingsatlas.nl/1255)
- [Flora van Nederland — Krabbenscheer](https://www.floravannederland.nl/planten/krabbenscheer)
- [Wilde planten in Nederland en België — Krabbenscheer](https://www.wilde-planten.nl/krabbenscheer.htm)
- [RHS — Stratiotes aloides](https://www.rhs.org.uk/plants/17806/stratiotes-aloides/details)
- [RHS — Pistia stratiotes (watersla)](https://www.rhs.org.uk/plants/13171/pistia-stratiotes/details)
- [RHS — Shade gardening (definities zon en schaduw)](https://www.rhs.org.uk/advice/profile?pid=934)
- [PFAF — Stratiotes aloides](https://pfaf.org/user/Plant.aspx?LatinName=Stratiotes+aloides)
- [De Vlinderstichting — Groene glazenmaker](https://vlinderstichting.nl/libel/groene-glazenmaker/)
- [Vogelbescherming — Zwarte stern](https://www.vogelbescherming.nl/ontdek-vogels/kennis-over-vogels/vogelgids/vogel/zwarte-stern)
- [Biovijver — Krabbenscheer (plaatsen en onderhoud)](https://biovijver.nl/vijverflora/vijverplanten/drijfplanten/krabbenscheer/)
- [Vijvermeester — Krabbenscheer (prijs, diepte, aantal)](https://vijvermeester.nl/krabbescheer.html)
- [Vijverplantenland — Krabbenscheer los (prijs)](https://www.vijverplantenland.nl/shop/stratiotes-aloides-krabbescheer/)
- [Vijverkenner — Krabbenscheer (prijs)](https://vijverkenner.nl/waterplanten/drijfplanten/stratiotes-aloides/)
- [Wikimedia Commons — Leaf: photo by Velela (Public domain)](https://commons.wikimedia.org/wiki/File:Water_soldier_plants.JPG)
- [Wikimedia Commons — Flower: photo by Velela (Public domain)](https://commons.wikimedia.org/wiki/File:Water_soldier_flower.JPG)

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