Cold-Hardy Pachycaul Trees

[ahosey01]

Looking for some suggestions for cold-hardy pachycaul trees that won't be killed by dips into the teens.  I'm in zone 9a.

Already can think of:

Brachychiton populneus

Brachychiton rupestris

Fouquieria formosa

Fourquieria columnaris

And MAYBE Ceiba speciosa but I have almost no experience with that plant and can't be certain.

Any more?  Any thoughts on Ceiba speciosa?

[Keys6505]

Maybe Moringa Drouhardii?  I've been searching for one but so far no luck.

[Matthew92]

Apparently Brachychiton rupestris can take dips into the teens.

Brachychiton rupestris at San Marcos Growers (smgrowers.com)

[Xerarch]

Ceiba speciosa might be a stretch for Wickenburg, I've seen some around town in greater Phoenix that look decent but they do get nipped back with cold.  The ones down here in Corpus were HEAVILY damaged by 18 degrees here, large mature specimens were killed nearly to the ground and have resprouted from the lower trunk, others faired a little better than that, some died outright.  Of course 18 degrees for you would not be as bad as 18 degrees here, especially this particular event we had in February so maybe they would do better.  Even so, the ones I've seen in Phoenix only looked ok, maybe the soil, maybe the heat, not sure.

Brachychiton populneus are actually pretty tough, I've seen them look perfect while things like Sissoo have taken moderate damage.

Brachychiton rupestris, there is a Brachychiton at the Glendale public library that isn't populneus, it might be rupestris, has a nice fat trunk. So that might be doable although when I saw it, the leaves looked a little beat up, might not be thrilled with the environment.

There are several Fouquieria columnaris at Boyce Thompson Arboretum which I assume would be a fairly good parallel to your climate, they look like they have been damaged by frost at times and aren't as big or nice as the ones at the Desert Botanical Gardens, granted it's probably been 10 years since I've seen them.  If you haven't been to Boyce Thompson I highly recommend it, would be a great place to get some ideas. 

[Silas_Sancona]

1 hour ago, ahosey01 said:

Looking for some suggestions for cold-hardy pachycaul trees that won't be killed by dips into the teens.  I'm in zone 9a.

Already can think of:

Brachychiton populneus

Brachychiton rupestris

Fouquieria formosa

Fourquieria columnaris

And MAYBE Ceiba speciosa but I have almost no experience with that plant and can't be certain.

Any more?  Any thoughts on Ceiba speciosa?

Question F. formosa tolerating anything below ..roughly 22F.  If it can, doubt it would attain the proportions it can where it won't get knocked back more than occasionally.  F.  macdougalii  ...might..  take slightly lower cold, ..dry cold.. once bigger. 
 

As far as trees, C. speciosa has survived lower 20s, maybe slightly colder outside Tucson, with damage.. Pretty sure both C. insignis and aesculifolia v. parvifolia run about the same level of cold tolerance -once bigger.  Bursera microphylla might be the only member of the Genus that could take the low low 20s, but again, likely won't attain tree size proportions if subjected to frost / freeze damage more than once every 10-20 years.

Highly doubt any of the Boswellia, or Commiphora will tolerate low 20s or below regularly either. Pachycormus discolor might be worth testing ...though you may really be pushing your luck up there.

[Silas_Sancona]

6 minutes ago, Xerarch said:

Ceiba speciosa might be a stretch for Wickenburg, I've seen some around town in greater Phoenix that look decent but they do get nipped back with cold.  The ones down here in Corpus were HEAVILY damaged by 18 degrees here, large mature specimens were killed nearly to the ground and have resprouted from the lower trunk, others faired a little better than that, some died outright.  Of course 18 degrees for you would not be as bad as 18 degrees here, especially this particular event we had in February so maybe they would do better.  Even so, the ones I've seen in Phoenix only looked ok, maybe the soil, maybe the heat, not sure.

Brachychiton populneus are actually pretty tough, I've seen them look perfect while things like Sissoo have taken moderate damage.

Brachychiton rupestris, there is a Brachychiton at the Glendale public library that isn't populneus, it might be rupestris, has a nice fat trunk. So that might be doable although when I saw it, the leaves looked a little beat up, might not be thrilled with the environment.

There are several Fouquieria columnaris at Boyce Thompson Arboretum which I assume would be a fairly good parallel to your climate, they look like they have been damaged by frost at times and aren't as big or nice as the ones at the Desert Botanical Gardens, granted it's probably been 10 years since I've seen them.  If you haven't been to Boyce Thompson I highly recommend it, would be a great place to get some ideas. 

Not sure i'd consider the F. columnaris up at Boyce " small " anymore. 

F. columnaris in the main Cactus Garden.. Some others in the Wallace / Baja Gardens also. From October's trip, visit # 3 for the year:





 

[ahosey01]

21 minutes ago, Silas_Sancona said:

Not sure i'd consider the F. columnaris up at Boyce " small " anymore. 

F. columnaris in the main Cactus Garden.. Some others in the Wallace / Baja Gardens also. From October's trip, visit # 3 for the year:





 

My buddy Bob, who is now like 90 something, sold these to BT back in the 60s I believe.  He said he was working at the Arizona-Sonora museum in the 70s and temps in a bad freeze dropped to like 15F.  Said it defoliated all the ocotillo and none of the boojums were affected.  Those things are TOUGH.

[msporty]

Have you looked at University of AZ? They have a comprehensive list of plantings there. Tempe looks like an hour away, so hopefully you can extrapolate.

https://arboretum.arizona.edu/heritage-trees

 

Also, have you seen the articles about Jason Eslamieh from Minatree? He has Boswellia growing outdoors in the same region.

 

[ahosey01]

15 hours ago, msporty said:

Have you looked at University of AZ? They have a comprehensive list of plantings there. Tempe looks like an hour away, so hopefully you can extrapolate.

https://arboretum.arizona.edu/heritage-trees

 

Also, have you seen the articles about Jason Eslamieh from Minatree? He has Boswellia growing outdoors in the same region.

 

Unfortunately I’m in a weird spot weather-wise in Wickenburg.  Daytime highs are generally within a few degrees of Tempe or Mesa, but night time lows get pretty low.  27F multiple times per year is common in my yard. Royals will grow to maturity in Tempe and don’t last a month in a Wickenburg winter, despite the similarities of our climates.

This is the primary problem here - I’m just outside the realm of where most pachycauls will grow.

[ahosey01]

On 11/30/2021 at 8:11 PM, Xerarch said:

Ceiba speciosa might be a stretch for Wickenburg, I've seen some around town in greater Phoenix that look decent but they do get nipped back with cold.  The ones down here in Corpus were HEAVILY damaged by 18 degrees here, large mature specimens were killed nearly to the ground and have resprouted from the lower trunk, others faired a little better than that, some died outright.  Of course 18 degrees for you would not be as bad as 18 degrees here, especially this particular event we had in February so maybe they would do better.  Even so, the ones I've seen in Phoenix only looked ok, maybe the soil, maybe the heat, not sure.

Brachychiton populneus are actually pretty tough, I've seen them look perfect while things like Sissoo have taken moderate damage.

Brachychiton rupestris, there is a Brachychiton at the Glendale public library that isn't populneus, it might be rupestris, has a nice fat trunk. So that might be doable although when I saw it, the leaves looked a little beat up, might not be thrilled with the environment.

There are several Fouquieria columnaris at Boyce Thompson Arboretum which I assume would be a fairly good parallel to your climate, they look like they have been damaged by frost at times and aren't as big or nice as the ones at the Desert Botanical Gardens, granted it's probably been 10 years since I've seen them.  If you haven't been to Boyce Thompson I highly recommend it, would be a great place to get some ideas. 

There is a Ceiba species growing at U of A which is large and mature.  I Google street viewed it and there was a shot from Jan 08, so a year or so after the big 07 freeze when Wickenburg got to 17F.  It looked pretty good in the street view, from what I can see, and is still there and still healthy.  They say it’s Ceiba insignis but I’m uncertain myself.

[Silas_Sancona]

24 minutes ago, ahosey01 said:

There is a Ceiba species growing at U of A which is large and mature.  I Google street viewed it and there was a shot from Jan 08, so a year or so after the big 07 freeze when Wickenburg got to 17F.  It looked pretty good in the street view, from what I can see, and is still there and still healthy.  They say it’s Ceiba insignis but I’m uncertain myself.

It's insignis..  Not positive, but they might have C. speciosa also.  Bach's Cactus has a few C. speciosa that have survived about as cold ..or colder lows w/ damage.