Water Soldier - Stratiotes aloides: Planting and Growing

Botany and description

The water aloe, also known by its scientific name Stratiotes aloides and its common names such as water soldier, aquatic aloe or water pineapple, is an aquatic plant belonging to the Hydrocharitaceae family (Hydrocharitaceae). The genus name, Stratiotes, derives from the ancient Greek “stratiotēs”, meaning soldier, referring to its robust sword-shaped leaves, evoking a natural armour.

In its natural habitat, this plant is typical of stagnant or slow-moving waters, such as ponds, ditches, lakes and marshes. It thrives particularly in fresh, nutrient-rich water, while requiring good light to develop fully. Native to Europe and Asia, Stratiotes aloides is mainly found in northern and central Europe, from the Netherlands to Scandinavia, through Germany and the United Kingdom. It extends as far as Russia and western Siberia. However, in some regions, this plant has become rare, particularly due to pollution and habitat destruction. Due to the decline of natural wetland habitats, it is a protected plant in France.

Foliage and flowering of Stratiotes aloides. On the right, botanical plate (circa 1903).

The water aloe is a perennial aquatic plant that forms magnificent floating rosettes on the surface, reminiscent of terrestrial aloes. These rosettes, compact and elegant, can measure between 20 and 50 centimetres in diameter, with rigid, sharp leaves. Their lance-shaped form, combined with finely serrated edges, gives them a unique and functional appearance. These leaves, which can grow up to 60 centimetres long, display light to dark green hues, sometimes dotted with reddish reflections as they age. In addition to their beauty, the leaves play an essential ecological role by oxygenating the water and limiting algae proliferation by shading the water surface.

The root system of this plant is primarily floating, with roots extending into the water to absorb dissolved nutrients. Although it may occasionally anchor temporarily in sediments, it remains primarily a floating species. This characteristic allows it to adapt to variations in depth and light in its aquatic environment.

In spring and summer, the water aloe stands out with its delicate flowering, which typically occurs between May and July. The flowers, borne on the water’s surface, are unisexual and illustrate the dioecious nature of the plant, with distinct male and female individuals. The white flowers, with pale yellow centres, measure about three to four centimetres in diameter. The male flowers, slightly larger and more spectacular, contribute to pollination, a process that occurs through water, thanks to an adaptation called hydrophily (pollen is transported by water).

Stratiotes aloides flowering

The fruiting of the water aloe remains a rare event, especially outside its natural habitat. When it occurs, it produces small ovoid fruits filled with seeds, maturing underwater. However, this plant mainly propagates vegetatively, through its stolons, creeping lateral stems that allow rapid colonisation of favourable aquatic areas.

The water aloe plays an important ecological role in its ecosystem. It provides valuable shelter and breeding grounds for many aquatic species, from fish to insects. In winter, this plant adopts a remarkable survival strategy: it sinks into the depths of water bodies to escape freezing, resurfacing when warmer weather returns thanks to its air-filled tissues.

Finally, this plant is not only useful in its natural habitat. In artificial ponds, it is highly valued for its aesthetic appeal and its ability to purify water by absorbing excess nutrients. It is also used in phytoremediation* programmes to combat eutrophication**. However, its excessive proliferation, possible in nutrient-rich waters, can sometimes become problematic, requiring careful management.

*Phytoremediation is an ecological technique that uses plants to clean up polluted soils, water or air by absorbing, degrading or immobilising contaminants.

**Eutrophication is an ecological imbalance in aquatic environments caused by an excess of nutrients (particularly nitrates and phosphates), leading to algae proliferation and a decrease in available oxygen, which threatens fauna and flora.

Our favourite varieties

[product sku=”87660″ blog_description=”Stratiotes aloides is an aquatic perennial forming a dense rosette of stiff, spiky leaves, rising to the water’s surface during its flowering period. Perfectly hardy and prolific, it’s valued for its water-purifying and oxygenating qualities in calm waters.” template=”listing1″ /]

Planting a water aloe

Where to plant?

The aquatic aloe should be placed in calm water, such as a pond or lake. It prefers:

• A sunny or lightly shaded area.
• A water depth between 30 and 100 cm. Below or above this, the plant may struggle to adapt.
• A nutrient-rich substrate to encourage its growth if you wish to anchor it.
• It dislikes excessively high temperatures, so avoid placing it in water that may exceed 22°C.

A note on the substrate

If planting in a basket, opt for a specially designed substrate, typically composed of a mix of clay, sand, and decomposed organic matter. This type of substrate is heavy enough to stabilise the plant and prevent it from floating or dispersing in the water.

To complement this, it is advisable to add a layer of gravel or coarse sand, about two to three centimetres thick, on top of the substrate. This helps keep the substrate in place while preventing nutrients from leaching into the water.

Finally, avoid using fresh organic matter, such as undecomposed compost. These materials could excessively enrich the water with nutrients and promote eutrophication, an ecological imbalance harmful to the pond.

When to plant?

The best time to “plant” the aquatic aloe is in spring (April) or late summer (September), when temperatures are still mild or the water begins to warm. This allows the plant to establish itself before winter.

How to plant?

• • Recommended!: For floating planting, simply place the aquatic aloe rosettes on the surface. They will adapt naturally, and their roots will float in the water. The silt at the bottom of the pond should consist of slightly acidic clay.
  • For anchored planting: secure the plant in a basket with aquatic substrate and place it at the recommended depth at the bottom of the pond. However, this method goes against the plant’s biology. Prefer the first option, which is much more natural!
    

Water aloe care

Maintaining Stratiotes aloides is relatively straightforward, as this aquatic plant is robust and self-sufficient in suitable conditions. Here are the key aspects to consider for its care and balance in a pond or water feature:

Monitoring Growth

The water aloe spreads quickly via stolons. In a small pond, it can become invasive. To prevent overcrowding:

• Remove excess rosettes regularly, especially in summer, when the plant is in full growth.
• Divide clumps if they become too dense, which also helps renew the population and encourages healthy growth.

Removing Dead Leaves

Over time, some leaves may yellow or decompose:

• Remove them by hand to prevent them from breaking down in the water and contributing to organic buildup, which could lead to eutrophication.

Natural Wintering

The water aloe adopts a natural winter strategy:

• As temperatures drop, it sinks to the bottom of the pond, where it remains dormant, protected from frost. No special care is needed during this period.
• In spring, the plant will resurface to resume its growth cycle.

Managing Light and Nutrients

The water aloe requires light to thrive:

• Avoid letting the pond become entirely covered by other floating plants, such as duckweed, which could smother it.
• Maintain a nutrient balance in the water. If the water becomes too rich, reduce organic input (such as leaves or plant debris) or add other aquatic plants to absorb excess nutrients.

In some countries, the plant has become invasive

Possible diseases and pests

Potential Diseases

• Filamentous algae
  Algae can proliferate in nutrient-rich water, covering the leaves of the aquatic aloe and limiting the available light. Although not a disease per se, smothering by algae can weaken the plant.
  • Prevention: maintain a good nutrient balance in the water and introduce other aquatic plants to limit excess.
• Leaf rot
  In poorly oxygenated or stagnant water, leaves may begin to rot, especially if covered with organic debris. This can affect the overall health of the plant.
  • Prevention: regularly remove dead or damaged leaves to prevent decomposition.

Potential Pests

• Aquatic aphids (notably Rhopalosiphum nymphaeae and similar species)
  These small sap-sucking insects can infest the emerged leaves of the aquatic aloe, causing the plant to weaken.
  • Treatment: rinse infested leaves with fresh water or allow natural predators like ladybirds to intervene.
• Aquatic beetle larvae
  Some aquatic insect larvae may nibble on the leaves or roots of the aquatic aloe, causing minor damage.
  • Natural solution: introduce fish that feed on these larvae, such as gambusia or carp.
• Aquatic snails
  Some snails, although useful for cleaning ponds, may sometimes chew on the leaves of the aquatic aloe, especially if other food sources are lacking.
  • Prevention: monitor the snail population and remove excess if necessary.

All these “pests” are clearly not pests in the case of the aquatic aloe, so don’t worry too much and let nature take its course. In 95% of cases, nothing will happen.

Propagation of the aquatic aloe

The aquatic aloe mainly (and easily!) propagates through vegetative division. Seed formation is very rare.

Propagation by dividing rosettes

The aquatic aloe can simply propagate naturally through its stolons. The creeping stems that form around the main plant will give rise to new rosettes without human intervention. If you wish to encourage this natural propagation, ensure the stolons remain in good contact with the water. They will eventually develop roots and produce new rosettes that can be separated once sufficiently established.

• When to divide?
  The best time to carry out this division is in spring or early summer, when the plant is in full growth. This allows the new rosettes to establish well before winter arrives.
• How to divide?
  1. Remove the mother plant from the water gently to access the rosettes formed around the main plant.
  2. Separate the rosettes: each rosette is attached to the plant by a stolon (a creeping stem). Use your hands or a clean, sharp knife to cut the stolons and separate the rosettes.
  3. Replant the rosettes: the separated rosettes can be directly floated back on the pond’s surface or anchored in a light aquatic substrate if you prefer to fix them.

Care for new plants

The new rosettes, whether divided or naturally formed, require the same conditions as the mother plant:

• Nutrient-rich water, without excess.
• Good sunlight and a calm pond environment.

How to best pair water aloe with other aquatic plants?

With its elegant silhouette and floating habit, the water aloe blends seamlessly with a wide variety of aquatic plants, whether floating, submerged or marginal.

For visual and ecological balance, it is wise to combine the water aloe with plants that occupy different levels of the pond. On the surface, it can be paired with delicate floating plants like water lilies (Nymphaea), which bring large round leaves and colourful flowers that contrast with the water aloe’s sleek rosettes. Other floating plants, such as frogbit (Hydrocharis morsus-ranae), can also be used, but sparingly to avoid blocking the light the water aloe needs.

In submerged areas, oxygenating plants such as spiked water milfoil (Myriophyllum spicatum) or common water crowfoot (Ranunculus aquatilis) complement the water aloe perfectly. These plants help maintain clear, well-oxygenated water.

Marginal zones, where water meets the banks, offer another level of pairing. Plants like yellow flag iris (Iris pseudacorus), broadleaf cattail (Typha latifolia) or water horsetail (Equisetum fluviatile) add height and texture that contrast with the water aloe’s floating habit. These marginal plants are ideal for filtering water by capturing excess nutrients, thus reducing the risk of eutrophication.

Finally, to enhance aesthetic appeal while preserving the pond’s balance, it is important to ensure that none of the companion plants dominate the medium. The water aloe, though hardy, can be outcompeted by overly prolific species. Regular maintenance, such as controlling floating plant spread or thinning marginal plant clumps, will help maintain a harmonious space where each plant thrives.

Around Stratiotes aloides: yellow flag iris, cattails, water crowfoot, water lilies and water horsetail.