Cephalocereus Senilis

Cephalocereus senilis is an endangered cactus from Mexico. It is columnar in size that rarely can branch out, with prolonged growth. The cactus grows only about 4 inches per year. It reaches 3 feet in height raised in the home, and up to 40 feet if wild. They have spines in the form of gray hair that serves to protect them from the cold. Because of their curious appearance, they are called “Old Man’s Head.”. They produce large white flowers. These flowers only bloom at night, in mid-spring or early summer when the cactus is about ten years old. To properly develop their spines in the form of hair, the cactus should be exposed to sunlight. When they are young, Cephalocereus senilis does not withstand temperatures below 50ºF. When they are adults, they can stand even 40ºF.

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A picture of Cephalocereus Senilis @floratopia

This species of cactus can live for more than a century. Although this cactus presents its characteristic white hair from the first moment, it is still a prickly cactus. Its spines are yellow and are born just before its coat of fur. It is not recommended to touch them without caution.

Irrigation

The cactus can be grown both, indoors and outdoors. However, it is more common to see it out thanks to its need for abundant sunlight to grow and develop its hair optimally. When produced in a pot, it is advisable to fill it with a light substrate with good drainage; the pumice is an ideal option. But if you are one of those who like to prepare your substrate with a little fine gravel and black peat you can make an excellent substrate for your Cephalocereus senilis. If we want to plant it in our garden, the soil must be equally light. It must not accumulate waterlogging since the Old Man’s Head cactus will not be able to withstand a flood. To take the appropriate precautionary measures, you can dig the hole to plant it and fill it with a little substrate to ensure better soil drainage.

Regardless of the type of crop that we want to give our Cephalocereus senilis, we must consider that water drainage is the most crucial factor. No water must remain. We can use some other materials so that our substrate is safe. And it has adequate drainage which is coarse sand or washed river sand. Which are quite mineral and are not compact since they can rot at the root quickly.

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Image: IG@liliacacti_hossein_h

Weather Conditions

The solar explosion is essential for the “Old Man’s Head,” so it should ideally be outside. It would be best if you gave it sunlight, preferably direct sunlight, for long periods. If you are not used to directing exposure, it is best to acclimatize it little by little to avoid damage from burns. The importance of this intense and prolonged exposure is its characteristic hair. These hairs protect our cactus against harmful rays. Besides, the direct Sun helps them grow faster and more robust. The cultivation in totally shaded places can result in partial or even total paralysis in the growth of our Cephalocereus senilis.    

Despite being a cactus and needing direct and prolonged sunlight, the ideal temperature of the “Old Man’s Head” is not very high; it is around 59ºF, being able to withstand interior temperatures of up to 68ºF without significant problem. When the cold and winter seasons arrive, it would be convenient to keep it in a fresh and dry part inside the house. There are adult specimens in the wild capable of facing 32ºF during these freezing times, depending on their age and size. The cactus should not be exposed to such low temperatures or frost, during the first years.

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Image: IG@cheyennebotanic

Watering

Cephalocereus senilis is a too delicate specimen when it comes to irrigation. Its base is susceptible and prone to rotting if it is watered directly or remains wet for a long time. It does not withstand even high humidity for long periods. Its waterings must be highly moderate and sporadic. It is vital for our cactus that we hope that the earth is parched before thinking about watering it again. The frequency of irrigation will not be the same during the winter, being that in summer we watered little; in winter, it should receive almost no water. This plant should be moistened when the soil is arid, and even then, it is advisable to allow about two days to pass. The curious thing about these cacti is that they are also somewhat susceptible to drought when they are young. If we have them in a pot, we must be cautious in the summertime. To prevent it from dehydrating we must water the soil as soon as it is scorched.

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IG@grancactus

Fertilizing

The spring and early summer seasons are ideal for fertilizing our Cephalocereus senilis. We should provide him with a mineral fertilizer rich in lime or a standard cactus fertilizer to grow his characteristic “white hairs.” Still, it is essential to be careful not to overdose. Flowering occurs in older cacti with more than 15 years of age and usually occurs only outdoors; it is almost impossible to flow in indoor specimens successfully. Its flowers arise from a very hairy body developed on the stem’s sides; they are tubular flowers with red, white, and pinkish pigmentation. These flowers usually fully bloom at night.

Cephalocereus senilis can be easily propagated from seed. It is preferable to do this during spring or summer. We must place these in trays with a cactus substrate. Keep them in a bright area with enough indirect light and water so that the soil remains moist. If everything goes well, we should have germinated seeds between ten and fifteen days after planting them. The “Old Man’s Head” cactus needs to be transplanted every two to three years. During the spring, into a larger container to provide it with a renewed space to grow.

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Image: IG@martynurquijo

Risks

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Image: Cephalocereus senilis Risk of Rot

The most significant risks of Cephalocereus senilis are excess water, which can rot the plant efficiently and quickly, and pests of both woolly mealybugs or fungi. Some of these pests are often difficult to detect, thanks to the fact that the “white hairs” cover its stem completely, making it almost impossible to see it with the naked eye; even the thorns are difficult to notice. This feature means we must be vigilant, especially in the summer when these pests usually invade our cactus.

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