This genus includes a single species, native to the deserts of northern and central America. It is a very slow-growing cactus, and very long-lived, which can reach 18-20 meters in height, employing us for 200 years; the saguaro plants are columnar for many years, when they reach the 150-200 cm of height they tend to branch; they have 15-20 ribs and gray spines, yellow in the upper areolas. The adult plants, of 30-40 years, in spring produce large white flowers, very fragrant, which are followed by large red fruits, oblong, edible, containing innumerable black seeds.
Exposure: these plants are used to the desert climate, therefore they prefer very sunny locations; they fear the cold, and exposure to temperatures below 4-5 degrees causes irreparable damage, so they should be kept indoors for the entire autumn and winter. Watering: does not require abundant watering, usually from April to September is water it well every 15-20 days, waiting for the soil to dry well between one watering and another; with the arrival of autumn the watering should be reduced, until it is completely suspended in winter. This plant certainly tolerates complete drought better than excessive watering. During the growing season it is good to add small amounts of fertilizer for cacti to the water of the watering once a month, without exceeding.
Saguaro - Carnegieia gigantea: Cultivation
Soil: cultivate the saguaro in a good compost for cactaceae, rich in sand and coarse material, to ensure excellent drainage.Multiplication: occurs by seed, even if the seeds are difficult to find; sow in autumn in a mixture of sand and peat in equal parts, the sowing container should be kept in a shady place, away from sunlight, warm and slightly damp, the seedlings will germinate fairly quickly, but the growth is very slow; when they are large enough to be handled they must be planted in individual containers, this can happen even after two or three years from sowing: in this period remember that the saguaro seeds in nature tend to germinate in the shelter of trees and shrubs, so in place warm but shady. Pests and diseases: the excesses of fertilizer and watering quickly cause the plant to rot; may be affected by cochineal, aphids and red spider mites.