Scientific name: Gymnocalycium mihanovichii
Genus: Gymnocalycium. It derives from the Greek and means “naked calyx” in reference to the way in which the flowers are born from the plant, without protection on the calyx of the bud.
Species: mihanovichii. It takes its name from the botanist M. Mihanovich
Origin: The G. mihanovichii species is widespread especially in the cold and cloudy areas of southern Argentina and Paraguay (Chaco Boreal)
Habitat: it grows under the bushes where it receives direct sunlight only a few months a year.
It is a small cactus with a globular shape depressed at the apex, it can reach 5-6 cm in diameter and 4 cm in height. It is a plant that branches (suckers) from the base, usually has 8 well-marked ribs with transverse grooves. The main characteristic of this species is the coloring of the epidermis. Regardless of the exposure, the color is variable and ranges from green to reddish or completely red (chlorophyll-free) in the rubra form (“HIBOTAN”). In nature, it can also be dark green, sometimes almost dark brown. white with short thorns. It blooms in spring and the flowers have a silky appearance and can be white with green shades, or pink or yellow/green.
Among the most common varieties, we find: Gymnocalycium mihanovichii var. friedrichii which produces purple-pink flowers, the flowers wide open and has high ribs and threads with horizontal variegations near the areolas.
The red HIBOTAN hybrid form completely free of chlorophyll is marketed grafted on Hylocereus to ensure rapid growth but on the other hand, it is not durable and should be re-grafted every 2 years as it rarely takes root and grows on its own roots. The variegated forms, on the other hand, can be cultivated frankly.
Cultivation: it is an easy plant to cultivate, it likes a bright position but not direct sun, especially for the varied forms. Give water regularly in summer when dry not in winter. It is quite frost-resistant (down to -5 ° C) if kept in a well-ventilated and bright position.
The forms without chlorophyll grafted on Hylocereus instead must be grown as if they were Hylocereus therefore watered regularly in summer, they like more humidity than the other cacti and in winter they do not survive and rot easily if the temperature drops below 10 ° C.
Flowering cactus is something wonderfully spectacular. We have already talked about very particular species of cactus with a beautiful flowering (see Christmas Cactus or the beautiful Easter Cactus) and this has allowed us to understand that the combination of cactus/flower is real and not an impossible goal to achieve.
The flowering of Gymnocalycium gives showy flowers, with the typical funnel shape and the most varied colors that embrace the darker shades of red or the more delicate shades of pink or white. Very decorative flowers that develop when temperatures begin to rise: spring and summer are the seasons during which to admire these beautiful stylish accessories, elegantly worn by these thorny plants.
Usually, the flowers develop on specimens of 2 or 3 years and to obtain a beautiful flowering it is necessary to rest the plant in a fresh environment, fertilize and ensure a lot of light for all species. In this way, the flowers will not be long in coming and will last longer.
Tips for growing Gymnocalycium
Like all succulents, they do not have particular requests, but in silence, they occupy one of the many free places in the audience of plants that are easy to grow. This does not mean that once planted they can be forgotten and left without any care: exposure, correct irrigation, and soil are factors to be kept under control at all times.
Let’s see how to take care of the colorful Gymnocalycium.
Cultivation in pots
The perfect pot for these plants is small in size and with a drainage hole on the bottom. They can be safely planted near other components of the Cactaceae family in larger bowls.
The soil to be used for pot cultivation of Gymnocalycium is specific for Cactaceae, but also a universal quality potting soil, combined with parts of coarse sand, can be fine. Never use soil that has already been exploited for other crops. The repotting must be carried out (in autumn) when the stem of the plant has by now exhausted the available space, reaching to touch the edges of the pot.
Gymnocalycium pot cultivation
Gymnocalycium do not need large pots at the beginning (Stuart CC BY-NC 2.0)
Cultivation in open ground
Growing Gymnocalyciums in the garden is always a risk. They are quite resistant plants and that do not require particular care, but they are very small and if not placed in precise, clearly visible points, you risk crushing them. The best thing to do is to plant cacti in small flower beds, perhaps surrounded by artificially raised curbs.
The cultivation in open ground can take place provided that: the light is able to reach the plants without obstacles, the soil is porous and draining, the irrigations take place regularly and that the temperatures do not drop below 8 ° C.
Cultivation on the terrace (or windowsill)
On the terrace, the Gymnocalycium grows well and can embellish raised parts with exposure in bright light. On the windowsill these plants will have no problem, the important thing is that the window is not facing north.
The perfect temperature to watch strong Gymnocalyciums grow is between 15 and 25 ° C. They also tolerate lower temperatures, but only during the resting phase and in sheltered places. At home, never place pots near heat sources.
The brightness level required by the species belonging to the genus we are describing is very high. Lots of light, but never direct contact with the sun’s rays, especially during the central hours of the hottest summer days. The intense light is used to preserve the lively coloring.
How should the perfect soil for Gymnocalyciums be? Loose and well-drained, these are the main characteristics that must never be missing. An excellent substrate is formed by specific soil for Cactaceae, coarse sand, and a part of river sand. Even a high-quality universal potting soil can be fine, as long as it is combined with draining elements.
The soil for Gymnocalyciums must be particularly draining (LynnK827 CC BY-NC-ND 2.0)
Water only when the substrate is completely dry. Gymnocalycium waterings must never be too frequent, let alone abundant. Once every 5-7 days in the summer and once every 3 weeks during the winter. Too much humidity and constantly impregnated soil can cause root rot.
Gymnocalycium multiplication can take place by:
seed (spring): the seeds must be planted in a soil and sand substrate at a distance of about 1cm from each other. Only in this case, the soil must be kept constantly humid until germination. The container must be placed in a place with little light and a constant temperature of 21 °
By sucker: to complete this operation perfectly, it is necessary to extract the plant from the ground. The suckers, which develop at the base, must be picked up gently and placed in a container with only damp sand.
By grafting: in this case the suckers are grafted onto the stems of other plants. In the case of Gymnocalycum, it is often possible to graft on some Hylocereus species.
Intervene only during the spring and summer period (no fertilization during autumn and winter). Fertilization of Gymnocalycium must be done every 20 days using a specific fertilizer for Cactaceae to be administered to the plant after moistening the soil. A good fertilizer is rich in nitrogen, phosphorus, potassium, and microelements such as molybdenum, boron, and zinc.
For the species of the genus Gymnocalycium, there is no mention of real pruning, but of a specific cleaning operation. With a brush you can literally dust the plant, to prevent dust from blocking the breathing pores and to wipe out any mealybugs. A simple operation to be repeated regularly every month.
No pruning, for the Gymnocalycium just a simple “dusting”
Pests, diseases and other adversities
Although Gymnocalyciums are labeled as cacti resistant to multiple pest attacks (attacks of aphids and mealybugs are rare), they can be severely tested by fungal diseases. The dark-colored spots on the surface of the plant are the alarm bell. In this case, the fungi that cause root rot have begun their damage work. The cause is too moist and poorly draining soil. The consequence is the emptying of the stems and the death of the plant. To avoid this, just follow the instructions in the paragraph on irrigation (summarizing: little water, no water in the saucer, proceed with irrigation only when the substrate is completely dry).
Grafting Gymnocalycium onto the stems of the Hylocereus cactus is a widely used practice. We must thank the Japanese botanists, who have developed an infallible grafting technique, now used by experts from all over the world.
The genus Gymnocalycium is not part of the list of toxic and potentially dangerous plants.
Language of flowers
Like other cacti, Gymnocalycium also has a precise meaning in the language of flowers. Strength, tenacity, and great ability to resist adversity. Among the plants to give away, they are highly appreciated.