The mammillaria genus is one of the most numerous of the cacti, in fact it has about three hundred species of succulent plants, all originating in Mexico and South America; they are very particular and showy plants, and have over time obtained the approval of most succulent lovers; in fact they are among the most widespread in cultivation, and can easily be found in any nursery, village fair, market stall. The name derives from the term breast, as the stem of the mammillarias does not have ribs, but is completely divided into smaller or more elongated, conical or cylindrical breasts; at the apex of every single breast there is an areola, generally equipped with thorns, erect or arched, often white, sometimes yellow; some species have a single further spine that rises from the center of the areola in the sense of breast growth, this spine is usually of a hooked shape. The spines of mammillaria are very showy, organized in small combs or tufts, numerous or single, white or dark, often accompanied by a thick white or pinkish hair. Many mammillaria bloom profusely in spring, with great ease; the flowers are produced in the part of the youngest plant, that is the apical one, and they bloom in the axilla that forms at the base of the udders. Mammillaria flowers are usually pink, but there are species with white, green, yellow, red and striated flowers; the flowers are followed by a small fruit containing the fertile seeds. Some species have a short period of vegetative rest in August, often followed by a second flowering, less abundant than spring.
Most species of mammillaria It is small in size, with a rounded stem, or briefly columnar, which remains below 9-10 cm in height; some can reach 25-30 cm in height, and they can develop into solos, branch out or sometimes even creep.
Grow the mammillaria
Mammillaria are native to areas of the globe characterized by stony and porous soils and a dry climate, so in general they behave like most cacti. They settle in well-lit areas, with at least a few hours of direct sun every day, but it is good to avoid the hottest hours or completely sunny areas, especially in summer, when the direct sun could ruin the skin of the plants by burning them; a semi-sunny exposure is then chosen, with a veiled shadow in the middle of the day. Watering will be sporadic and not very generous, to be carried out only when the weather is warm, therefore from April to September; in the months of the year when the climate is cool and the days are short it is advisable to water the mammillaria very little, or even for nothing if the plant is grown in a cold greenhouse, or in any case in a cold place, without heating. In any case, even in the vegetative season, we water only when the soil is dry, considering that a small earthenware pot left in the June sun may need watering on alternate days, or every three days, approximately; every 15-20 days, mix the water with a fertilizer rich in potassium and poor in nitrogen.
The ideal containers for mammillarias are earthenware pots, of contained dimensions, in which we will place a compound consisting of universal soil, mixed with pozzolana, lapillus or pumice stone, in equal parts, so as to obtain a well permeable substrate, free from stagnation water, harmful to the plant.
These plants, like many cacti, can withstand winter temperatures even close to zero ° C, provided they are kept in a very dry area, free of humidity, especially in the ground; so if in September-October we stop watering the plants, we can try to leave them even on the terrace, on a shelf, or in a cold greenhouse, in a place where they are not in any case reached by the weather; if we do not have any type of shelter it is convenient to keep them indoors, possibly in an unheated room, like a stairwell, where the plants receive a lot of light and a cool climate; in fact, as with most cacti, these plants tend to bloom with greater probability if in winter they can enjoy a period of vegetative rest, which is precluded if they live in the apartment all winter, with about 20 ° C of temperature throughout the day.
Some species of mammillaria go through a period of semi-vegetative rest even in summer, in August, a period in which it is good to avoid watering them; often flourish when the cool climate of late August arrives.
The adversity of mammillaria
Surely the first enemy for succulent plants is always humidity: when it is excessive and stagnant, the plants begin to become soft and dark, and our cures often do not give any result, and the plant dies; it is of various types of rottenness, with roots or stems, favored in their development by certain factors such as, first of all, the excesses of watering, the excesses of nitrogen fertilizers, the lack of direct sunlight. The first plants subject to various types of rottenness are those grown at home throughout the year, without direct light, with excessive humidity, and a fake spring climate that is constant for every month and season.
Proper cultivation often allows us to forget almost completely about the fear of rot; in any case these plants tend to be particularly affected, often even in the case in which watering the whole stem tends to wet, which presents various sinuosities where the water can stop; we avoid therefore to wet the stem and the small udders, rather we moisten the ground.
The other sworn enemy of the mammillaria is surely the cochineal, which finds in this plant various places where to hide, between armpits, white hairs and thorns; therefore it often happens that it is difficult to find insects, when we see them they have now colonized the whole plant and it is difficult to eradicate them.
Fortunately, mealybugs often lurk on those plants that do not have proper ventilation and are kept too dry; so let's remember, especially in the greenhouse, to favor the exchange of air around the plants. If we have so many succulent plants, and above all if we keep them in winter in those little do-it-yourself locks, it is convenient to treat the plants with an anticocciniglia product, in late winter, when the temperatures are rising slightly.