Stenocereus pruinosus-Gray Ghost, Organ Pipe

Stenocereus pruinosus on 7-19-16, #274-66.

Gray Ghost, Organ Pipe, Pitayo de Octubre (of October), Pitaya

Stenocereus pruinosus

sten-oh-KER-ee-us  proo-in-NO-sus

Synonyms of Stenocereus pruinosus (19 as of 12-25-20): Cactus pruinosus Monv. ex Steud., Cereus laevigatus Salm-Dyck, Cereus pruinosus (Otto ex Pfeiff.) C.F.Först., Cereus roridus Pfeiff., Echinocactus pruinosus Otto ex Pfeiff., Griseocactus pruinosus (Otto ex Pfeiff.) Guiggi, Griseocereus pruinosus (Otto ex Pfeiff.) Guiggi, Lemaireocereus laevigatus (Salm-Dyck) Borg, Lemaireocereus pruinosus (Otto ex Pfeiff.) Britton & Rose, Lemaireocereus schumannii (Mathsson ex K.Schum.) Britton & Rose, Neogriseocereus pruinosus (Otto ex Pfeiff.) Guiggi, Pachycereus schumannii (Mathsson ex K.Schum.) C.Nelson, Rathbunia laevigata (Salm-Dyck) P.V.Heath, Rathbunia laevigata var. schumannii (Mathsson ex K.Schum.) P.V.Heath, Rathbunia pruinosa (Otto ex Pfeiff.) P.V.Heath, Ritterocereus laevigatus (Salm-Dyck) Backeb., Ritterocereus pruinosus (Otto ex Pfeiff.) Backeb., Stenocereus laevigatus (Salm-Dyck) Buxb., Stenocereus laevigatus var. schumannii (Mathsson ex K.Schum.) P.V.Heath

Stenocereus pruinosus (Otto ex Pfeiff.) Buxb. is the correct and accepted scientific name for this cactus. It was described by this name by Franz Buxbaum in Botanische Studien in 1961. It was first named and described as Echinocactus pruinosus by Christoph Friedrich Otto and Louis (Ludwig) Karl George Pfeiffer in Enumeratio Diagnostica Cactearum in 1837.

The genus, Stenocereus (A.Berger) Riccob., was named by Vincenzo Riccobono and first mentioned in Bollettino delle Reale Orto Botanico di Palermo in 1909. It replaces Cereus subsp. Stenocereus which was named by Alwin Berger and first mentioned in the Annual Report of the Missouri Botanical Garden in 1905. Plants of the World Online by Kew lists 21 accepted species in the Stenocereus genus (as of 12-25-20 when I am updating this page). It is a member of the plant family Cactaceae with 144 genera. Those numbers could change as updates are made.

THERE ARE SEVERAL LINKS AND GROWING RECOMMENDATIONS AT THE BOTTOM OF THE PAGE FOR FURTHER READING.

Stenocereus pruinosus on 5-31-17, #339-41.

I brought my Stenocereus pruinosus home from Wal-Mart on 2-1-16. It was growing in a 2 1/2” (4 oz.) pot and it measured approximately 2 7/8” tall x 2 3/4” wide at the time. The label states:

Lemaireocereus pruinosus is a powdery, gray columnar cactus that grows to 20’ in height in time. White nocturnal flower. Native habitat is Puebla, Mexico. Protect from frost. Provide bright light/sun; hardy to 32 degrees F.; to 6’ tall. Water thoroughly when soil is dry.”

Of course, Lemaireocereus pruinosus is not the correct name now…

Stenocereus pruinosus on 9-5-17, #371-22.

Stenocereus pruinosus can e found in its native habitat in Chiapas, Guerrero, Oaxaca, Puebla, and Veracruz in Mexico at 2,600 to 6,200 feet (800 to 1,900 meters) above sea level where they grow in tropical deciduous forests. They are known for their edible fruit.

Stenocereus pruinosus on 10-17-17, #384-24.

When I brought my plants in for the winter on October 17, 2017, the Stenocereus pruinosus measured 3 3/4″ tall x 2 3/4″ wide. Ummm… That measurement may have included the spines which I later ignored when taking measurements.

Stenocereus pruinosus, from the top, on 10-17-17, #384-25.

Stenocereus pruinosus grows to become a large shrubby or tree-like cactus. Stems usually have one or more trunks that can grow to 13-16 feet (4-5 meters) tall and a little over 3” to about 4” ( 8-10 cm) in diameter. They normally have 5-6 ribs but can have as many as 8-10, that are widely set and have wavy margins. The areoles are normally around 1 1/2” (3-4 cm) apart and produce 1-4  small grayish to brownish central spines and 5-8 smaller radial spines that are the same color. When it flowers, they come from new growth on the tips of the stems.

<<<<2018>>>>

Stenocereus pruinosus on 1-18-18, #401-13.

Doing very well inside for the winter, the Stenocereus pruinosus was snuggled with many other cactus and succulents on a table in my bedroom when the above photo was taken. They are getting lots of good sun from a south-facing window.

Stenocereus pruinosus on 5-17-18, #443-98.

Back outside again for the summer…

Stenocereus pruinosus on 7-29-18, #487-96.

After the Japanese Beetle invasion, I moved the potted plants, cactus, and succulents to the front and back porch of the house. The Stenocereus pruinosus is enjoying its summer in the sun on the back porch.

I had to move the potted plants inside for the winter on October 10 because the forecast was calling for an “F” in a few days and the nighttime temperatures were getting cooler. The Stenocereus pruinosus measured 3 7/8″ tall x 3″ wide but I forgot to take its photo… GEEZ!

Stenocereus pruinosus on 11-29-18, #534-33.

November 29 was a nice spring-like day, so I took the cactus to the back porch for a photoshoot. I was working on a post to show the difference between the cactus in my collection.

Stenocereus pruinosus close-up on 12-1-18, #535-24.

Stenocereus pruinosus is a very interesting plant for sure. Its areoles produce 1-4 short and stout central spines. Llifle also says they have 5-8 radial spines… My cactus has 2-4 spines on its areoles, usually 3, but it is hard to say if they are radial spines or central spines… The dusty-white appearance is from the “bloom” which is a characteristic of this species.

<<<<2019>>>>

Stenocereus pruinosus on 6-22-19, #593-43.

All the plants made it through the winter and were glad to be outside for the summer. I put the Stenocereus pruinosus and most of the other cactus on the back porch.

I was fairly busy over the summer so I didn’t take a lot of photos of the potted plants. They all did very well despite a little neglect.

Stenocereus pruinosus at 4 3/4″ tall x 2 3/4″ wide on 10-11-19, #639-89.

The next thing I knew, I had to move the potted plants inside for the winter on October 11 because an “F” was in the forecast. I always take photos of the plants when I move them inside and measure the cactus and some of the succulents. The Stenocereus pruinosus measured 4 3/4″ tall x 2 3/4″ wide. That’s pretty good considering it was only 2 7/8″ tall when I brought it home on February 1, 2016. At least I didn’t forget it’s photo this time…

<<<<2020>>>>

Stenocereus pruinosus (Gray Ghost) at 5 1/4″ tall x 2 3/4″ wide on 10-15-20, #747-100.

I had to move the potted plants inside for the winter on October 15 because an “F” was in the forecast. As always, I take photographs and measurements of the cactus when I bring them in. The Stenocereus pruinosus did very well over the summer and measured 5 1/4″ tall x 2 3/4″ wide on October 15.

Stenocereus pruinosus (Grey Ghost) from the top on 10-15-20, #747-101.

The above photo is a top view of the Stenocereus pruinosus sporting a purplish glow from being in the sun.

USEFUL INFORMATION:
Family: Cactaceae
Origin: Oaxaca, Puebla, and Veracruz in Mexico
Zones: USDA Zones 9b-11(25 to 40° F)
Size: 10-20’… UMMM… 
*Light: Sun to light shade
**Soil: Very well-draining. Good quality potting soil amended with pumice (50/50) or additional perlite and chicken grit (2-1-1).
***Water: Average during the summer months, barely during the winter.

*During the summer, I keep most of my cactus on the back deck where they receive full sun. During the winter most cactus aren’t picky about the light because they are basically dormant. For several winters, mine were in front of the east-facing sliding door in the dining room so they didn’t get much light but they did great. I built a new shelf for the bedroom so now they are in front of a west-facing window. Most of the succulents are on a shelf in a south-facing window in a cool bedroom but a few are in my bedroom.

**When it comes to potting soil, finding the “sweet spot” is not exactly that easy when materials are limited. Cactus and succulent enthusiasts (and experts) do not recommend using peat-based commercial mixes but what choice is there for most of us. They say to use a loam-based mix… Hmmm… Our soil is loam, so do I just use dirt? Well, no because “dirt” is heavy and you need a “light” material. There is A LOT of cactus and succulent recipes online and some get pretty elaborate. Many say to use sand as an ingredient, but if you do that, it needs to be very coarse, like builders sand, because “ordinary” sand, like for sandboxes, is too fine and it clogs up the air space between the coarser ingredients. For MANY years I used 2 parts Miracle Grow or Schultz Potting amended with an additional 1 part of perlite and 1 part chicken grit. Schultz doesn’t seem to have as many large pieces of bark. Cactus and succulent enthusiasts recommended using pumice instead of perlite and grit so I checked it out… The “guy” at General Pumice (online) recommended using a 50/50 mix of potting soil and pumice. General Pumice has 3 different sizes to choose from depending on the size of the pot. SO, in 2018 I bought a bag of 1/8″ and mixed it 50/50 with Miracle Grow Potting Soil. I liked it pretty well. Then in 2020, since most of the cactus were in larger pots, I ordered the 1/4″ size. Pumice has a lot of benefits over perlite and has nutrients that are added to the soil when watering. Pumice is also heavier so it stays mixed in the soil instead of “floating” to the top. Still, there is the issue of the mix getting very hard once you stop watering the plants during the winter when you stop watering. I think this is because of the peat in the potting soil… SO, instead of re-potting the cactus and succulents in the spring, I started doing it during the fall and winter so their soil would be loose. Since you don’t water as frequently during the winter if at all, the timed-release fertilizer does not activate. I have not tried coir, but I am looking into it… 

I think a lot of growing tips online are written by people who never grew succulents and cactus. They just copy from one website and paste it to theirs. You have to sort of mimic the soil where species grow in their native habitat. For that, you almost have to go see for yourself… Typically, they grow in fairly rocky soil.

***I water my cactus and succulents on a regular basis during the summer but barely ever in the winter (maybe a little in January) until close to time to take them back outside. 

You can read my Cactus Talk & Update and Cactus & Succulent Tips to get my opinion about growing cactus and succulents.

When you bring your new plants home from the store, you need to check their roots and the soil to see if they are wet. If so, you may want to re-pot it right away. It is advisable to re-pot them in a better potting soil more suitable for cactus and succulents.

I have really enjoyed the Stenocereus pruinosus as a companion and I think it is a great looking specimen. It is much different than the other cactus in my collection. I like the silver color of the bloom and the way it gets darker with more light. There is also a variegated variety of this cactus which would also be very interesting.

I hope you enjoyed this page and maybe found it useful. If you have any comments, questions or suggestions, I would like to hear from you. Please click on “like” if you visited this page. It helps us bloggers stay motivated. 🙂 You can check out the links below for further reading. The links take you directly to the genus and species of this plant.

FOR FURTHER READING:
PLANTS OF THE WORLD ONLINE (GENUS/SPECIES)
WIKIPEDIA (GENUS/SPECIES)
LLIFLE (ENCYCLOPEDIA OF LIVING FORMS)
DAVE’S GARDEN
CACTUGUIDE
LEARN 2 GROW
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