Cacti

Acanthocalycium Guide: How to Grow & Care for the “Barbed Wire Cactus”

Read our guide to Acanthocalycium for everything you will ever need to know! Tips for planting & caring for “Barbed Wire Cactus”
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If you are looking for a low maintenance decorative cactus with abundant blooms, you can’t go wrong with the Barbed Wire Cactus. This succulent belongs to the Acanthocalycium genus which includes several cactus species, all of which originate from Argentina, mostly from the Cordoba region.

Acanthocalycium is also known as the Sword pear or the Triangle cactus. This type of cactus is very robust, and it can survive harsh environments, being particularly resistant to draughts.

Read on if you want to learn more about growing and caring for the Barbed Wire Cactus.

About the Barbed Wire Cactus

  • The name of this cactus genus comes from the jointure of two green words, ‘akantha’ and ‘kalyx’ which roughly translate into prickly buds or a chalice with thorns.
  • These types of cacti are not susceptible to diseases, but certain pests like mealy bugs, aphids, and whitefly can often cause damage. Inspect the plant regularly to catch infestations in the early stages so that they are more likely to respond to non-toxic treatments.
  • The Acanthocalycium cacti have no known medicinal properties and there are no records of them ever being used in alternative medicine.
  • Originally, this genus was described in 1935 by Curt Backenberg. Initially, Backenberg classified 12 species under this genus, many of which were later reclassified under other genus categories.
  • The toxicity of these plants is unknown, but due to their prickly buds, it is unlikely that pets will want to meddle with these plants. Nonetheless, it is best to keep them out of the reach of pets and children, to prevent accidental stings.
  • These cacti mature quite rapidly, but they maintain a small and manageable size even when fully grown.
  • They can be grown outdoors in proper environmental conditions, but it is best to allow them to mature indoors where you can control their environment, and only move them outdoors when they are strong enough to handle the harsher conditions.
  • If you live in a warm region where you can grow cacti outdoors, the Barbed Wire Cactus will produce beautiful flowers that will attract pollynators.
acanthocalycium thionanthum cactus
Acanthocalycium thionanthum cactus

Barbed Wire Cactus Features: An Overview

  • Among the most popular species in the Acanthocalycium genus we have: Ferrarii, Aurantiacum, Peitscherianum, Violaceum, Glaucum, Klimpelianum, Spiniflorum, and Thionantum. These species have slight differences of size and shape, but they differ mostly in blooms which can be yellow, milky white with yellow centers, dusty pink, purple, or various shades of orange.
  • The most spectacular blooms are the orange ones that have a burning look, with a bright yellow center and orange petals infused with shades of red. Each species has its varieties, and with small differences in the shade of the flours and the spines.
  • Most of these cactus species have a round shape when they are young, but they elongate as they mature, gaining an elliptical shape.
  • The Barbed Wire cacti are mainly green with a hint of gray or yellow in some cases. They have about 20 ribs with spiky areolas. The spikes are silver on top and they grow darker towards the base of the plant.
  • An Acanthocalycium cactus will reach maturity in 3 years and it can reach an average height of 15 cm with about 8-15 cm in diameter. Some species can grow taller.
  • These cactus species start blooming in spring, but their blooms persist throughout summer. The blooms grow on top of the cactus, featuring floral tubes with a scale-like appearance. The flowers have a funnel shape and a considerable size with a diameter of 3-4 cm and a length of 5 cm. The flowers turn into 2 cm fruit, with a round shape and a green scaly exterior.
  • Their spines are gathered in areoles. There are about 10-20 spines per areole, each measuring about 2 cm. The spines have a gold color when the plant is young and they turn gray as the plant matures.
White flowers of acanthocalycium klimpelianum
White flowers of acanthocalycium klimpelianum

Growing Barbed Wire Cactus

The Barbed Wire Cactus loves the sun, so try to place it near a window that gets at least 6 hours of sunlight per day. During the warmer months, you can provide your cactus with a delicate partial shade like a thin curtain.

This cactus can also be grown outdoors, provided that the outdoor environment is suitable for it. It thrives in USDA zones 8 to 11. However, keep in mind that this little cactus genus is not frost-tolerant, so if the temperatures drop below 7 degrees, we advise you to move it indoors in a warm and airy environment.

This hardy cactus can survive even lower temperatures, but it will pause its development, and it will take some damage depending on the surrounding temperature and humidity. In higher humidity, the plant will be more damaged if the temperature drops. Temperatures above 24 degrees Celsius will be tolerated by the plant, but it is best not to test it and shelter it from direct sunlight during heat waves.

Acanthocalycium spiniflirum
Acanthocalycium spiniflirum

Acanthocalycium cacti require regular feeding to develop to their full potential, so you should feed them once a month during their growing period, which is from early May to October. If the plants outgrow their containers and you need to repot them, try to do this in early spring.

The repotting process will cause less shock during the growing season and the mild spring weather is also more suitable for an environmental change. It is best to allow the soil to dry out completely before attempting to repot a plant. Dry soil will also make it easier for you to remove the plant from its current pot without damaging its roots. Moreover, allow the plant to recover in dry soil after the repotting procedure and only water it after a couple of days when it has accommodated in the new pot.

Watering Barbed Wire Cactus

Since this is a drought-tolerant plant, it will not mind if you forget to water it from time to time. In suitable outdoor conditions, this plant is one of the most popular choices for xeriscaping, which is the practice of landscaping with minimal or no water except for the water provided by the natural climate. Nonetheless, try to provide shelter from wind and direct sunlight for the cactuses planted outdoors.

Indoors, you can water this plant every 4 days, and as winter approaches and the weather gets colder, you can decrease the watering frequency, to once every 7-10 days. While this plant is resistant to droughts, it does not fare well with overwatering. Excess water can severely damage the roots, so allow the soil to dry out completely between watering sessions. Moreover, use a container with a good drainage hole and make sure to throw away the water that gathers in the drip tray after watering the plant.

Propagating Barbed Wire Cactus

Propagation from seed is difficult, time-consuming and it has fewer chances of success than other propagation methods. Nonetheless, it can be done, with patience and proper care, and watching the seeds grow can be an educational experience. Moreover, it is the only available solution when it comes to barbed wire cactuses which rarely produce offsets.

To propagate from seed, you will need the seeds, a shallow container, and a special cactus soil mix, something predominantly porous with good drainage. You can also make your mixture using clay, lava grit or pumice, and some peat.

Acanthocalycium violaceum
Acanthocalycium violaceum

Cover the drainage holes and fill in your container with the cactus mix. Gently tap your container on a hard surface so that the soil can settle properly. Don’t press on the soil as this will hinder air circulation. Moreover, don’t fill in the container completely, but allow it two cm to the top, so that you can later cover the container with a lid. There is no need to dig holes. Simply press the seeds into the soil using your fingers and then gently sift the soil over the seeds.

Once the seeds are planted, cover the container with a sheet of glass or plastic, and place it in a warm and bright spot, but not in direct sunlight. Water the seeds every 3 days and you should see them sprout in a couple of weeks, at which point you will have to remove the lid. Young plants need proper air circulation, and a lower level of humidity to develop properly.

This plant is usually solitary, but it can sometimes develop offsets at its base. Propagation from offsets is relatively simple. Use a sharp blade to remove the offsets, allow them a couple of days to dry, and then plant them in a special cactus mix. You can use a growth hormone to give the new plants a boost of nutrients so that they can easily adapt to the separation.

We recommend Hoffman Organic Cactus and Succulent Soil Mix

In Conclusion

Like most cacti, the Barbed Wire Cactus is very low maintenance and due to its rich blooms, it is very popular among cacti lovers. Since it is a fast grower and it blooms with ease, it is great for beginner gardeners with little patience and discipline. The tropical look of this plant will add an eclectic vibe to any interior, and its showy blooms will always put your little cactus in the spotlight.

What type of Barbed Wire Cactus do you have? Let us know in the comments below!

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Miruna Secuianu

Miruna is an experienced content writer with a passion for gardening. She is the proud owner of an outdoor rose garden and an indoor collection of tiny succulents. She bought her first succulent 10 years ago - an adorable Echeveria Setosa. Now she owns more than 100 succulents and cacti of different colors, shapes, and sizes. Miruna is a versatile writer and, as you might have guessed, her favorite topic is gardening. Contact miruna@gardenbeast.com

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