One look at this plant is enough to understand the choice of name. Euphorbia trigona, the western cactus, has become an integral part of classic western films. The prickly fellow is also becoming increasingly popular in our part of the world. The cactus-like appearance of the plant is deceptive, as they belong to the species-rich family of succulents. The triangular milkweed feels at home in winter gardens and living rooms. The plants forgive many a care mistake and are therefore equally suitable for beginners and passionate hobby gardeners with experience. In terms of care and location, the plant has some requirements.


  • Often referred to as the Texas cactus.
  • The triangular milkweed belongs to the succulent species.
  • Can reach a maximum height of 2 m.
  • The ornamental leaf plant is a milkweed plant.
  • The poisonous sap can cause burns and rashes on the skin.

Location and substrate

The triangular milkweed is widespread in the warm regions of Africa and Asia. The western cactus is a cultivated form and has been deliberately selected for centuries. This measure contributed to the fact that today’s milkweed plants are unable to flower. Rather, it is the bizarre appearance that makes the succulent species fascinating. Contrary to what its trivial name suggests, the exotic plant does not belong to the “real cacti” group. However, its requirements in terms of location and maintenance are similar.

  • The western cactus likes it warm.
  • A full sun location is preferred.
  • The plant is satisfied with a light spot in partial shade.
  • Avoid drafts and direct heat sources.

The exotic animals can cope with dry room air. You can do without water-filled containers to increase the humidity with the triangular milkweed. It is not always possible to give the plant with its height of almost 2 m a south window seat. If a few hours of sunshine fall daily, the succulent will also thrive in darker places. There are still a few things to consider when choosing a location. With increasing age, the milkweed family can reach immense weight. This is in the shoots, not in the roots. The entire plant becomes top-heavy. To counteract this problem, a stable vessel must be selected. If necessary, larger stones on the bottom of the tub or in the planter provide the necessary counterweight. The western cactus reacts sensitively to drafts and constant contact with the branches. A passage area, such as the stairwell, is unsuitable for the succulent plant. In summer, the plant has no objection to moving to the garden. Slowly get used to the UV radiation. Otherwise, even sun-loving milkweed plants can suffer damage to the shoots. For the first few days, shield the succulents with a parasol, for example.

The slowly growing Euphorbia triogona needs a loose and well-drained substrate with a pH value between 6 and 7. The soil should be rich in humus and loamy, with a high addition of sand and pearls. The substrate can be mixed together with little effort. For this you need:

  • Torfsubstrat
  • Loamy earth
  • Quartz sand
  • Lavalite or pumice gravel

If you want to save yourself the trouble: Special succulent soil from specialist shops contains all the mineral components that the exotic plants need. Even when completely dry, the substrate remains crumbly and permeable. This promotes the growth and resilience of the exotic plants. Due to the strong root mass, the plant can “shift” itself in the container. An occasional check of the substrate is therefore advisable.

Tip : In winter, you can upgrade locations that are too dark and poor in light with plant lamps.

Watering and fertilizing

It is a myth that cacti and succulents can do without maintenance at all. Plants can cope with prolonged drought. However, if you want to avoid consequential damage, you shouldn’t burden this frugality too much. A water shortage is only slowly noticeable in the western cactus. The shoots become thinner and increasingly pale. Prevent this by watering properly.

  • Avoid water containing lime.
  • The substrate should dry on the surface.
  • The western cactus is watered all year round.

Excess water must not accumulate in the container, but must be able to drain off immediately. If necessary, porous material such as pottery shards or fine pebbles can help. Do not treat the succulent plant like an ordinary houseplant. The distance between the individual casting units is much longer here. A constantly moist soil leads to rot in the western cactus.

Like almost all plants, succulents cannot do without minerals. Despite their slow growth, the nutritional values ​​in the substrate are quickly exhausted. The upright striving Euphoria trigona have to be fertilized with a special cactus fertilizer every 8 to 12 weeks from March to August. This contains all the important minerals that succulents need. In liquid form, the nutrients can be administered directly via the irrigation water. This has the advantage that the agent is evenly distributed in the ground. In the resting phase, which extends approximately from September to February, the plant is not fertilized and only watered moderately.

Tip : “Less is more” – is the motto when fertilizing. Too high a concentration of fertilizers affects the plants and can cause lasting damage.


Its demands and the sensitivity to temperatures below 12 ° C make Euphorbia trigona unsuitable for permanent cultivation in the garden. Even temporary planting in the bed is not recommended. Planting the exotic milkweed family is easy.

  • The planter must be stable and around 5 cm larger than the roots of the succulent plant.
  • Put a drainage on the bottom of the bucket.
  • A 3 cm thick layer of substrate is applied over this.
  • Clean the roots of the succulent plant from the old substrate.
  • The root network should be able to soak in a bucket of lime-free water for 30 minutes.
  • Insert western cactus.
  • Fill the cavities with soil and press the plant into place.
  • Water the plant carefully.

Tip : Succulents from specialist shops are often offered for sale in normal potting soil. For the good of the plants, you should change this substrate quickly.


When the best time for a larger planter comes, depends on the growth of the western cactus. If the triangular milkweed feels at home in the selected location, it can completely root through the bucket within months. Other specimens, however, need 2 to 4 years for this. For a small western cactus, you can check the status of the roots by carefully lifting the plant out of the container. It is also repotted when the side shoots of the Euphorbia trigona reach the edge of the planter.

Proceed as you did when planting when moving the succulents. The new bucket should only be slightly larger than the one previously used. With the western cactus it is advisable to choose a wide container. This offers more floor space and you can better compensate for the weight of the shoots. Cutting back the roots is not recommended. You cannot use it to regulate the height of the exotic plant. It is more likely that the entire plant will be damaged by such a measure.


The triangular milkweed does not bloom. For this reason, propagation by sowing is impossible. The western cactus is successfully propagated using head cuttings.

  • Carefully break or cut off one of the top parts of the plant.
  • Let dry for 2 to 3 days.
  • Put in lean succulent soil.
  • Keep it evenly moist, but avoid waterlogging.

Cuttings and planter should be in a bright, warm place. Avoid direct sunlight. It can take a few weeks for the first roots to form. When the cuttings begin to develop their own shoots, the time has come to transplant. Enrich the substrate with humus and move Euphorbia trigona to its final location.

During the propagation you come into direct contact with the milk-like plant juices of the western cactus. Like all milkweed plants, care should be taken when handling the exotic plant. All parts of the succulent are highly poisonous. The sap of the plants can cause eczema and irritation on the skin. Chemical burns can occur in or on the mucous membranes. When working on the triangular milkweed, wear thick gloves and clean the tools. Small children and pets should be kept away from the plant.


Temperatures below 12 ° C pose a problem for the western cactus. In its original home in Africa and Asia, the plant can cope with tropical heat and direct sunlight. Even a cool night in summer can affect the plant enormously. Before the cold season comes, prepare for the milkweed family. The succulents take a dormant phase from October to the end of February. During these months, the consumption of water and nutrients is reduced enormously. In winter, water is only moderately and just enough that the root ball does not dry off completely. During this time, the fertilizer may remain on the shelf without being noticed. The location for the winter should be bright and have a temperature between 12 and 15 ° C. Dry room air is tolerated,

Diseases and pests

Only a few fungal pathogens and germs can endanger the plant with the fascinating leaf decoration. The situation is different with pests. Western cacti are susceptible to spider mites and mealybugs. In large and strong plants, the cell sap sucking insects rarely cause any significant damage. But as the population increases, so does the danger to other houseplants. Take action against the pests as soon as you discover them.

In the case of spider mite infestation , in many cases it is not the insects, but their sticky excretion that attracts attention first. If you take a closer look, you can see the fine, cobweb-like webs. Spider mites love a dry and warm environment.

  • Shower the entire plant.
  • Carefully wipe off parts of the plant with soapy water.
  • Spray the plant with a diluted stock of nettles.

high level of humidity makes life difficult for the unwanted crawlers. Often the method suggested is to water the entire plant firmly and to wrap it completely with foil for 1 to 2 days. This measure does not always work reliably and should be used with caution, especially with succulents. This method should not be used on severely weakened plants.

Mealybugs are easy to spot because of their cotton ball-like shape. Like spider mites, they feed on the cell sap of the plants. The biological control with home remedies is tedious. If implemented consistently, you can get rid of the pests again.

  • Give succulents a vigorous shower.
  • Dab affected areas with high percentage alcohol.
  • Collect animals.

There is a great temptation to use insecticides right at the start of control measures. Only use this if all other methods have been ineffective. With indoor plants, you can also hope for the help of a natural predator. Parasitic wasps are harmless to humans, but they help to decimate the harmful insects. If the food source runs dry, the parasitic wasps die.


The western cactus with its bizarre growth is an interesting plant. The warmth-loving milkweed plant is an asset to the conservatory at home, but is also satisfied with a bright location in living rooms. The plant is robust, but it has special requirements in terms of care and substrate.

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