Putting crab claws in the garden pond is a pretty good idea, even if the name doesn’t sound like it at first. Water aloe in the garden pond sounds much better. In fact, the Stratiotes aloides affects the health of the ecosystem in the garden pond in much the same way that the real aloe affects the health of the skin. Crab claws also attract insects. They have become so rare with us that they are under the strictest nature protection. The name comes from the appearance of a leaf. Crab claws belong in the garden pond for close-to-nature gardeners.

The crab claw – prickly but useful beauty

This crab claw or water aloe belongs to the frog bite family. The “crab claws” are only the bracts around the flower, rather soft plant material, but the leaves of the water aloe are brittle structures with clear spines.


It also has a flower resembling water lilies and fairly broad leaves reminiscent of aloe, up to 40 cm long, which can grow into pretty rosettes with a diameter of around 80 cm. From the outside, the crab claws are very decorative.

Aquatic aloes are floating plants because they float on the water surface (or underwater plants because they only do so in the summer season). If they have just submerged, they also decorate. They ensure that the pond water shimmers in all possible shades of green. A pond without such a play of colors in the water looks unhealthy, like dead.

In any case, it is good for your garden pond if the crab claws spread their rosettes over (or under) the water surface of the pond, because a long leaf and root system hangs down from the rosettes, which makes a decisive contribution to the biological purification of the pond water. This means that the crab claw is part of the most important pond plant society, which, as a nutrient competitor to the algae, ensures order in and under the water and is responsible for good water quality and enough oxygen even in the deeper pond zones. This is a prerequisite for survival for all fish that like to stay close to the bottom of the pond.

The right environment for the water aloe

The water aloe can not only reach impressive diameters as a single plant, but it will also multiply if the environment suits it. It is therefore not suitable for very tiny garden ponds, which it quickly overgrows completely. While you can get rid of “too many crab claws” by simply collecting them, it gets annoying if you have to do it all the time.

The water aloe needs some nutrients in the water, especially in artificially created and balanced ponds, care must be taken to ensure that there is a sufficient supply of nutrients. A crab claw in a natural pond should usually spread magnificently, even when there is a relative lack of nutrients.

There is a wide variety of information about the pH of water. Crab claws should mainly like alkaline waters or only thrive really well in an acidic environment. This suggests they will likely grow satisfactorily in almost anything outside of caustic alkali or acid baths. It is more important that the water aloe finds a muddy subsoil. In completely transparent (inanimate) water it will simply starve.

Crab claws are most commonly found outdoors in northern Germany, especially in stagnant waters with a relatively low lime content. But there aren’t that many water aloes in natural waters in Central Europe anymore. In Germany, their population is even considered highly endangered. This is said to be due to mechanically (too) clean, weeded ditches, the intensive pond management that is common today and sport anglers who exterminate water aloes in natural waters because they hinder them in casting and retrieving the fishing line.

So you are doing an ecologically good work if you put a water aloe in your garden pond. This also applies to the area above the water, the white flowers are often visited by insects.

With regard to the pond zone, the crab claw is one of the plants for the deep zone. It is suitable for depths from 60 cm in a sunny to partially shaded pond.

Good companions

Conditions similar to crab claws may e.g. B. the oxygen plant water pen (Hottonia palustris), the yellow water lily (Nuphar lutea), the sea ​​jug (Nymphoides peltata), the water chestnut (Trapa natans) and the floating pondweed (Potamogeton natans). Most of these plants are rooted a little more firmly in the pond bottom than crab claws.

The crab claws also ensure that algae do not multiply excessively. In this function it can be supported by frog bite (Hydrocharis morsus-ranae) and water thousand leaf (Myriophyllum).

Appearance, flowering, departure

The water aloe comes to the surface of the water only when it is in bloom, at least in water of good natural quality.

In the pond of a “pond chemist”, which is kept completely transparent with every possible means, the crab claws should curiously nibble on the chemical mix offered in the water and not even in summer rise to the surface, but break out in the depths in explosive growth. Then the individual rosettes and long roots grow all the way down to the bottom of the pond and prevent each other from rising to the surface of the water. They remain submerged, also bloom under water, so they thrive invisibly at first, but magnificently. What happens afterwards with the crab claws in such a chemical pond has not been handed down. The more natural and unpolluted the pond, the better the water aloe should thrive.

If everything is in order, the crab claw will rise before flowering and begin to bloom. Depending on the climate, the flowering period falls between June and September. After flowering, the crab claws will slowly retreat to the bottom of the pond to overwinter.

Buy crab claws

What some oh so nature-loving recreational anglers do constantly and without hesitation, eradicate crab claws, illegally and against the Federal Species Protection Act.

If an outdoor crab claw sanctuary nearby is almost irresistibly tempting, here’s a little “buy for fun” suggestion. Crab claws are grown in aquatic nurseries that cannot only be contacted over the internet. A visit can be worthwhile. In this way, buying crab claws can become an interesting excursion. When you create a pond for the first time, you can ask the experienced water gardener a lot of questions.

It is best to take a waterproof container with you for transport. The leaves of the crab claw dry up quite quickly in the air and are transported in the usual wet environment.


“Planting” the water aloe is fairly simple. It is not planted with a shovel, etc., but simply placed in the pond.

This can happen anytime in the spring. When creating a new pond, it is the turn of the crab claws after the rooting pond plants (and only when they are well established). Three crab claws should be used for every 10 square meters of open water.

care tips

The water aloe does not need care in the actual sense, the best care for it is an environment that is as natural as possible. The water aloe is also said to react very sensitively to all garden chemicals, especially total herbicides (round-up) are said to finish off them if they get the smallest concentrations.

Pond plants are not pruned in the gardening sense either. “Too many crab claws” is simply fished off and released into the next natural pond (if you have created a biotope, please always speak to the supervisor first).

It is more the case that the crab claws care for their environment. It has already protected some nutrient-rich small bodies of water from excessive nutrient accumulation. With a bit of luck, she could bring you an enchanting garden guest: the green mermaid “Aeshna viridis”. This is a beautiful dragonfly, up to 10 cm long, with a green body and a very decorative abdomen, blue-brown or green-brown pattern, really distinctive. The green mermaid is dependent on the water aloe. It is the only plant on which this almost extinct dragonfly lays its eggs. The Green Mosaic Maiden seems to smell salvation. It can often be found in garden ponds, which is why crab claws should be found in every larger garden pond.

The leaves of the crab claws are not spurned either, numerous small invertebrates settle on them, and aquatic snails use them as grazing land.

Crab claws overwinter

With the hibernation of crab claws you also have no work, as a native plant it is uncritically hardy with us.

It is no longer to be seen in winter anyway, after flowering the crab claws gradually retreat to the bottom of the pond. The leaves die off at the beginning of winter, and the water aloe begin to develop their overwintering organs called turions, also known as “winter buds”.

Next spring, the crab claws develop new leaves from the overwintering organs all by themselves and slowly come back to the surface.


Small daughter plants develop from the turions of the crab scissors in the spring. They continue to grow throughout the summer months. The daughter plants finally hang on stolons up to 0.5 m long. Together with the mother plant, they sink towards the bottom of the pond in autumn and overwinter. When they are “mature” enough (the following spring) they will ascend and root themselves.However, it takes a little time until the crab claws start this vegetative reproduction, depending on the size and, above all, depth of the body of water. Only when the propagation is well advanced does the water aloe develop so-called emersed (overhanging the water surface) leaves and flowers. That can take a few years.

These flowers then also develop seeds. Nevertheless, sexual reproduction plays only a very minor role in crab claws. There’s a reason for that. The crab claw is unisex, so the flowers on a plant are either male or female.

This means that generative propagation in a garden pond with only one plant will remain an eternal dream, even if you use a second crab claw. It will most likely be a male crab claw again. In all of Central Europe, only male plants actually occur.

With this reproductive strategy in the generative area, the crab claw has, so to speak, catapulted itself out of evolution. If you want to breed crab claws you will definitely have difficulties, female crab claws may not be that easy to acquire either. An idea would be import from the next holiday in Finland, where there are only female crab claws.

Crab claws belong in our garden ponds, for the sake of ecology and the environment. In addition, by planting a water aloe, you are helping to save an important aquatic plant species. The only surviving member of its genus (Stratiotes), which evolved about 65 million years ago. And you also save a strikingly beautiful large dragonfly.

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