Unfortunately, there is no common translated name for the Gymnocalycium cacti. The direct translation from the botanical name means “naked calyx”. As a rule, these are low-growing plants, usually solitary or in small clusters, with a spherical to short-cylindrical stem. Characteristic are the 4 to 15 ribs, which are usually broadly rounded and rarely warty. Most of these cacti have thorns. These can be very variable. Gymnocalycium cacti stay small, so you can cultivate several of them together in one container.
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These cacti can be distinguished from others by their flower buds. They are scaly in Gymnocalycium cacti, as are the flowers. The special thing about these cacti are the flowers. For the small plants, these are usually of impressive size. They open during the day and are funnel or bell shaped. The flower colors range from white, through yellow and pink to bright red.
Gymnocalycium cacti are native to Bolivia, southern Brazil, Paraguay, Uruguay and Argentina. There are many subgenera and species.
Types of Gymnocalycium cacti
The best-known of the Gymnocalycium cacti are the chlorophyll-free mutations, which are commercially available as “red ball cactus”. They are not green, but rather red and sometimes yellow to purple. These cacti are also called strawberry cactus or spider cactus. They are not capable of photosynthesis themselves. Therefore, they are grafted onto a green cactus (usually a Myrtillocactus). It is similar to grafting trees. The substrate serves as a nutrient supplier.
- G. ambatoense – comes from Argentina, grows solitary, spherical, reaches a diameter of 15 cm and a height of 5 to 10 cm. It has 9 to 17 ribs, a single, mostly straight central spine and nine to eleven slightly curved, protruding radial spines. The bell-shaped, silky white flowers have a light pink central stripe.
- G. amerhauseri – also native to Argentina, grows solitary and has dark green to bluish green shoots. Its shape is flattened spherical to spherical. The cactus is only about 2.5 cm high with a diameter of about 5 cm, usually has eight ribs, a central spine and five to seven radial spines: It impresses with funnel-shaped creamy white to light pink flowers.
- G. andreae – also comes from Argentina. This species has numerous subspecies, is spherical to depressed spherical in appearance, and is up to 15 cm in diameter. The cactus is about 5 cm high, has blue-green to blue-grey shoots, eight to twelve ribs that are clearly cross-grooved, a central spine and six to ten radial spines. The flowers are pale to bright sulfur yellow or white to light pink.
- G. baldianum – its homeland is Argentina. It grows singly and later in groups, depressed spherical and has grey-green to blue-green shoots. Its diameter is about 6 cm, its growth height is up to 10 cm. This cactus has nine to eleven ribs and five to seven radial spines. Its pink to deep red or purple flowers are particularly beautiful.
- G. bruchii – native to Argentina, is a very small but multi-headed cactus with a spherical body. It reaches a diameter of up to 6 cm and a growth height of up to 3.5 cm, has eight to 12, sometimes up to 17 ribs, one to three strong central spines and up to 24 smaller, delicate, brush-like radial spines. The delicate violet-pink to white flowers are not quite as large, but there are several. It is a floriferous species.
- G. denudatum – Native to Brazil, Uruguay, Argentina and Paraguay, it has a depressed spherical habit and a glossy dark green color. Its diameter reaches 6-8 cm, its height up to 3 cm. It has 5 to 8 very wide ribs and thick, strongly curved yellow spines. He also convinces with his shiny, pure white and large flowers.
- G. quehlianum – mostly solitary, occasionally growing in groups. It has grey-green shoots with a reddish tinge, a depressed spherical appearance and a diameter of 10 to 15 cm and is only 4 cm high. There are also 11 to 14 low ribs and five to seven thorns and white flowers with a reddish throat.
- G. saglione – native to Argentina and one of the largest species. It reaches up to 30 cm in diameter and 90 cm high (rarely). Its 13 to 32 ribs are sharply furrowed across. The cactus grows spherically and has a blue-green color. The spines are slightly curved towards the body, there are 8 to 10 radial spines, up to 4 cm long. The flowers are white or reddish, often many appear at the same time. It flowers only from a size of about 20 cm.
The Care of Gymnocalycium Cacti
Gymnocalycium cacti are easy to care for if they are in the right location and watered accurately. Otherwise, only the plant substrate is important. These cacti are among the less demanding. They are not divas, get by with little care. They do not like too much moisture and lime in the soil. For this, the substrate must be slightly acidic, otherwise there will be no growth and hardly any flowers. Gymnocalycium cacti enjoy a spot outside in the summer. But it shouldn’t get too hot. In summer, the plants also need a lot of water, in winter, on the other hand, they do better when dry. Otherwise there is not much to consider.
Gymnocalycium cacti like to be outside in the summer. They like the sun, but don’t want it to get too hot in the middle of the day. In winter, the cacti like to be cool. In any case, the plants like a lot of light.
- Bright with direct sunlight
- If there is too little light, the characteristic spherical shape is lost
- Also, the flower is only sparse or disappears completely.
- Normal room temperature
- In summer, an outdoor location is recommended, in the sun.
- 3 hours of sun a day is enough, but it can be more
- The place should be protected from rain. Every now and then water from above is not bad, but too much of it is.
- Species from mountain regions cannot cope with extreme heat. It is better not to stand too sunny, i.e. not in the midday sun or not in front of a radiating wall. G. mostii are particularly sensitive.
- Keep cooler in winter.
The plant substrate is one of the decisive factors for the plants to thrive. It should be quite mineral. Many growers use a purely mineral substrate, but it doesn’t have to be. However, a slightly acidic soil is important for growth and thriving and for flowering.
- Humus-rich substrate + a third sharp sand
- Mixture must be loose and permeable.
- A slightly acidic soil and a high mineral content are very important.
- When the soil is alkaline, plant growth stops.
- Also take care of the roots.
- Absolutely lime-free!
- Good results have also been obtained when cultivating in a purely mineral substrate, eg red brick dust.
Of course, when planting and potting, you have to be careful with the small plants. Above all, the sensitive roots must not be injured. When repotting, some experts recommend an annual deadline, while others rely on the fact that the soil should first be completely rooted. It is best to try out what suits the cacti better.
- It is best to plant and repot in spring
- A pot with a diameter of 8 cm is usually sufficient
- Repot only when the entire substrate is well rooted.
- Then you use a slightly larger pot.
- Otherwise just shake off the loose soil and put it back in the same pot.
watering and fertilizing
When pouring, it depends on a little finesse. In summer, the Gymnocalycium cacti need plenty of water, but not too much. The floor must not be constantly wet, but also not too dry. In winter, on the other hand, you can save water. The plants are better left almost completely dry. Gymnocalycium cacti are best watered from below.
- Keep evenly moist during the growing season
- Don’t water too much. The top layer of soil must always dry first.
- At the beginning of the growing season, spray the cacti with water when the weather is nice.
- It is ideal to only water the cacti from below, this way you can avoid rot caused by adhering water.
- Place cacti in a bowl filled with a little water and wait until the top layer of soil feels damp. Remove the plant and let it drain briefly.
- In winter, only water so much that the soil does not dry out completely, so only very little. Watering too little is much less dangerous than too much.
- Only fertilize every 14 days during the main growth period with a potassium-rich complete fertilizer
- Some lovers of this plant genus recommend a purely mineral fertilizer, eg pure granite grit or, as an alternative, red brick grit.
Hibernation is not difficult if you can provide a cool room and adequate light. Overwintering doesn’t do so well in a warm living room. The cacti often do not bloom and pest infestation and diseases often occur.
- A cool location is recommended in winter.
- It must be very bright, preferably in the sun.
- 5 to 8° C are ideal for hibernation.
- Water little or not at all.
- The cooler the location, the less water is needed.
- Too much water leads to rot quite quickly.
- The cacti, on the other hand, rarely dry out.
- Be sure to ventilate regularly!
Propagation succeeds by separating off kindel and by sowing. The Kindel version is much easier and is also fast. It works quite reliably. Sowing is not necessarily difficult, but often fails. The seed is often not of good quality or simply too old.
- Cut off runners with a sharp knife
- Let the cut surface of the Kindel dry for two to three days.
- Then place the child with the dried cut surface in a pot with fresh cactus soil.
- Seeds – must be fresh if possible, then the germination rate will be higher
- Temperatures not above 20° C
diseases and pests
With good care, the cacti are not susceptible to diseases and pests. Nevertheless, these can occur naturally.
- Mealybugs – Mealybugs are easily identified by their white, cotton-like webs. It is best to collect them carefully with a toothpick or something similar.
- Root pests (e.g. nematodes, nematodes) – often you only notice that you are harboring root pests when the plant is already too badly damaged. Then there isn’t much you can do. Flushing the roots helps, but usually only temporarily.
There are many different species and subspecies of Gymnocalycium cacti, so there is bound to be an interesting species for everyone. Of course, the cacti are particularly attractive when they are in bloom. You have the choice between cacti with large individual flowers or those with several smaller ones. That’s a matter of taste. I find it beneficial that these cacti really don’t require much maintenance. Those who cannot spare much time for plant care are well served with these specimens.