Trichocereus pachanoi

[Las Palmas Norte]

I'm looking for some solid info regarding hardiness for Trichocereus pachanoi (San Pedro cactus). My research has resulted in widely varying and conflicting information. Dry winters are the only thing that seems to be conclusively evident. Thanks in advance.

[Tom in Tucson]

4 hours ago, Las Palmas Norte said:

I'm looking for some solid info regarding hardiness for Trichocereus pachanoi (San Pedro cactus). My research has resulted in widely varying and conflicting information. Dry winters are the only thing that seems to be conclusively evident. Thanks in advance.

Frost tolerance is not as dependent on dry conditions like many of the smaller Mexican species, but almost any cactus will rot if kept too wet. The various species of Trichocereus do have a somewhat large cold hardiness range (15˚ to  25˚)F. T. pachanoi is usually damaged at 23˚.

Hi 108˚, Lo 83˚

[Las Palmas Norte]

2 hours ago, Tom in Tucson said:

... The various species of Trichocereus do have a somewhat large cold hardiness range (15˚ to  25˚)F. T. pachanoi is usually damaged at 23˚.

Maybe that's where some of the confusion originates. The plant tag with this one states minimum zone 9b which I think is about the 23°F limit you mention. Thanks for the info.

Regards, Barrie.

[Axel Amsterdam]

7 hours ago, Tom in Tucson said:

Frost tolerance is not as dependent on dry conditions like many of the smaller Mexican species, but almost any cactus will rot if kept too wet. The various species of Trichocereus do have a somewhat large cold hardiness range (15˚ to  25˚)F. T. pachanoi is usually damaged at 23˚.

Hi 108˚, Lo 83˚

Tom, would you say trichocereus is the more wet tolerant of the cacti? And do you know if golden barrel is affected by humidity/rain? I read some reports they surprisingly seem to be able to handle water better than other cacti.

Edited August 27, 2023 by Axel Amsterdam

[Rivera]

For what it's worth, this is one of the better growing cacti in San Francisco's fog belt. Minimum temps aren't an issue here, but it's cool and humid. Winter is rainy, though highly variable. 

[Tom in Tucson]

7 hours ago, Axel Amsterdam said:

Tom, would you say trichocereus is the more wet tolerant of the cacti? And do you know if golden barrel is affected by humidity/rain? I read some reports they surprisingly seem to be able to handle water better than other cacti.

Yes, even though many of them are native to some of the most arid regions of South America.

Golden barrel (Kroenleinia grusonii) will not only tolerate very cold winter temps., but they tolerate (but don't prefer) winter rainfall. As evidence of this fact, The Huntington Botanical Garden (near Pasadena, CA) has undoubtedly the largest number of these planted (on Earth) in some huge colony like settings. Like most of CA, almost all of the rain falls there during the Winter season.

Incidentally the native range of this species is in a fairly high altitude region. This may explain it's cold tolerance, but doesn't explain it's resistance to Winter rainfall. That area is nearly 100% visited by Summer showers.

Hi 108˚, Lo 83˚ Aug 26

Edited August 27, 2023 by Tom in Tucson

[Axel Amsterdam]

I don’t want to derail this topic but couldn’t resist this habitat picture, near Zacatecas

Edited August 27, 2023 by Axel Amsterdam