The cactus, a succulent plant par excellence
The shaded part of the cactus often tends to turn yellow and weaken: in practice, it is more sensitive to attacks by fungi and burns. This explains why the cactus must be turned periodically, so that each side receives the same amount of light. In the same way, a uniform growth is favored. Care must also be taken, on the other hand, to over-insolation, which could lead to a growth block and the appearance of a reddish color. Another danger in sight is the etiolation, typical of the location in an unsuitable environment. Before spring, high temperatures can favor the vegetative growth of some species, which begin to have a pale vegetative apex due to the lack of light, due for example to winter days or closed windows for too long. Therefore, it happens that the plant begins to spin or etiolate, that is to say to take a tapered shape and a yellowish color: if the growth is not immediately stopped, the cactus will be irreparably damaged, even from an aesthetic point of view , since, at the moment in which it will resume growing normally if it is brought back to the outside, a bottleneck will remain in correspondence with the etiolation. Not only: the clear part will be sensitive to burns. To avoid this problem, you need a low-temperature room, like the stairwell of a building.
What are burns and how they are treated
As for the burns, they are nothing but encrustations on the surface of the plant of light color, result of the drying of the external integument, due to the excess of light: light with respect to which it has not yet been able to get used to. These dead tissues in young plants or that show vigorous growth come off easily, as if it were a film, due to the increase in the size of the underlying stem; in the presence of slow growth, on the other hand, or of an adult plant, sunburn will most likely remain forever. It is also worth focusing on drainage, an essential characteristic of cactus survival. To be avoided are the compact soils, which are too asphyxiated: they prevent the very delicate roots from breathing, and they also retain excess water. The consequence is that the plant rots and dies, often affected by internal molds which also give rise to a stinky and soft mass. In order to improve the drainage of the substrate, an important action is the removal of the dust: all you need is a fine mesh filter and sieve the soil, minced and dry. The basic substrate can be composed in equal parts of river sand and peat, or universal soil, which is purchased without problems in any gardening store. However, the use of red and pumice lava, rich in minerals, can be equally effective: they are, however, materials available only in a few nurseries. An aspect to be taken into particular consideration is watering: during the summer, the cactus can be wet when the soil is dry. If it is sufficiently porous, it is enough to let twenty-four hours pass to be sure that, when on the surface it is dry, also on the bottom the humidity is contained.
The amount of water needed for the cactus
Experience, of course, plays a fundamental role in determining the amount of water needed, also because it is difficult to provide universal rules due to the many variables involved, from season to climate. It can however be specified that a cactus situated in a vessel no more than ten centimeters deep and small in size needs watering a day, paying attention, however, to avoiding fungal attacks. The administration of water must be uniform throughout the soil: the roots, in this way, will grow without too many differences, and evenly. In the event that only the surface of the succulent plant is wetted, the root system will develop upwards. The air exchange is favored by the flow of water up to the drainage holes through the substrate: the water that comes out in the saucer has the useful function of disposing of the excess minerals present in the soil. Also the age represents a factor that affects the water needs of the cactus: the young seedlings born from a seed, the so-called seedlings, need in fact a wet substrate for at least the eight weeks following the birth.
When they become stronger, the substrate can be allowed to dry out between waterings, especially after the appearance of the first leaves or the first thorns. As winter approaches, the plant enters a period of quiescence or rest, and stops growing: during this period it must almost never be watered, until the vegetative restart that occurs in spring. In the case of a species that can withstand frost, it can be left outdoors in the dry.