The Melocactus, as we said, are quite difficult to grow, as they need high temperatures throughout the year, low humidity and high luminosity. In summer, they do not like full sun, especially if placed outdoors, so we will find a place in mid-shade, very bright but characterized by a few hours of direct sunlight, and possibly it will be the coolest hours of the day.
In winter, they need temperatures over the 10-12°C, therefore they are cultivated in temperate greenhouse or in house, but always in a very luminous place, even in full sun, which, being low on the horizon, will not risk to burn the epidermis of the stems.
During the winter months we will water only sporadically, with small quantities of water, while in the summer we can water about one fly a week, avoiding to supply water if it has rained, or if the soil is still moist. Let’s always avoid wetting the cephalium, which otherwise is affected by mold and fungus.
The melocactus have a fairly wide and deep root system (compared to that of other cacti), for this reason they are generally not grown in common pots for cacti, very small, but are placed instead in large bowls, so that the roots can find all the space they need.
The substratum must be very porous, formed by universal mould, mixed with pumice, lapillus or pozzolana stone, or with any material useful for simulating a rocky and very permeable soil; if cultivated in unsuitable mould, the melocactus tend to get sick easily, in a short time.
The fertilizations are furnished only during the vegetative period, from April to September, about once a month; we always use a fertilizer for succulent plants, avoiding other types of fertilizers, which contain excessive quantities of nitrogen, dangerous for the cacti.
Melocactus: Propagating melocactus
These plants, unlike other cacti, do not grow and do not produce the so-called “children” at the base, even after several years of cultivation, but the fruits always contain a number of small fertile seeds. Before using them, let’s get rid of the pulp and let them dry in the sun for some days, then let’s dust them with some fungicide, so that they do not produce moulds or fungi once placed in the sowing pot.
Let’s prepare a good sowing soil, consisting of washed river sand and peat in equal parts; let’s place it in a sowing tray and water it well. It is important to wet this type of soil beforehand, because it tends to take some time before it rehydrates, especially if we use dry peat; moreover, if we wet it before, we won’t risk moving the seeds, once planted.
When the mould is well humid, let’s place it in a sub pot, and let’s spread the seeds, paying attention to distance them well; let’s cover it with a thin layer of vermiculite: it is an inert material, light and clear, which allows us to keep the seeds in place and to keep always a little of humidity on the surface of the soil, without removing the sun light from the seeds, which helps the germination.
We place the tray in a plastic bag, which we will close hermetically, so that it functions as a greenhouse, keeping the heat and humidity close to the seeds. The sowing tray should be placed in a warm and bright place, but without direct sunlight. Over the next few days we should be vigilant, making sure that the soil is always moist: if it seems dry to us, we should open the bag and put a little water in the saucer.
Once the seedlings are twinned, we take off the plastic bag, taking care, however, to keep the tray in an area not subject to strong winds. The young plants will have to be watered only when the ground is dry, and they prefer luminous and warm positions, just like the adult specimens.