Generalities: globose or slightly columnar cactus from Mexico. The number of species belonging to this genus is controversial, due to the variability of the forms and the similarity of some species to other cactaceae, usually the number is around ten. In nautra the stenocactus live in the rocky deserts or in the plains, they have numerous thin and waxy ribs, often even more than eighty, very particular as they are undulating. The areolas are usually small and bear many spines, straight or curved, never hooked; usually the central spine is very long, up to 6-8 cm. In spring they produce in the highest part some small funnel-shaped flowers, white, pink or red, whose petals have a darker line that divides them in half.
Exposure: these cactaceae love very bright positions, even in full sun; they fear the cold and do not bear temperatures below 5-6 degrees, for this reason it is advisable to shelter them at home during the winter or in a sheltered place.
Watering: during the growing season water at least once a week, waiting for the soil to be dry between one watering and another; in winter, watering more rarely, once a month or less if the plant is kept indoors, but if stenocactus is placed in a colder place, it is advisable to suspend the watering completely to allow the plant to rest for the winter. From March to October add a fertilizer for succulent plants to the irrigating water every 15-20 days.
Stenocactus pentacanthus: Soil and pests
Soil: as with many other cacti, even for stenocactus the soil must be very well drained, so it is advisable to use a substrate for succulent plants, rich in sand, appropriately added with coarse material, such as perlite or pumice stone.
Multiplication: stenocactus are generally single plants with no branches, so the only way to propagate them is by sowing: they are sown in spring in a compound made of sand and peat in equal parts, the seedlings will germinate quickly, but the growth of the stenocactus is slow , therefore they can remain in the seed container for a long time. The seeds of the stenocactus are not always fertile, so if you want to take them directly from the plant you should choose the seeds of several plants, to increase the chances of success; remember that the daughter plants are not always identical to the mother plant. Pests and diseases: Excesses of water cause root rot with great ease. Stenocactus are often attacked by mites and cochineal.