Growing Albizia Julibrissin (Persian Silk Tree) in cooler climates

[UK_Palms]

I have noticed there are a lot more Albizia's growing in London than I had first realised. A lot more. I have heard that they are only hardy down to about -5C or -6C (22-20F) at most, however that assertion can probably be called into question now, given that I have seen them growing in other cool locations. I don't know whether these are the hardier variant, or even how you would tell that? Some of these are in the colder parts of London and have been there a while, so they probably would have seen roughly -7C (18F) back in 2010. I have heard of Albizia surviving in places like Amsterdam, Paris, NYC, D.C. etc..?

All of these ones are in London...

\

 

There is a fantastic Albizia specimen much further north in Sheffield, which is in South Yorkshire at 53N. Anyone know what the furthest north specimen is in the world?

 

Although unrelated, I also spotted an Australian Bottle Brush tree (Callistemon) growing on a London street as well...

 

Edited January 10, 2022 by UK_Palms

[Silas_Sancona]

6 minutes ago, UK_Palms said:

I have noticed there are a lot more Albizia's growing in London than I had first realised. A lot more. I have heard that they are only hardy down to about -5C or -6C (22-20F) at most, however that assertion can probably be called into question now, given that I have seen them growing in other cool locations. I don't know whether these are the hardier variant, or even how you would tell that? Some of these are in the colder parts of London and have been there a while, so they probably would have seen roughly -7C (18F) back in 2010. I have heard of Albizia surviving in places like Amsterdam, Paris, NYC, D.C. etc..?

All of these ones are in London.

Wayyy hardier than the low 20s.. 

https://davesgarden.com/guides/pf/go/1764

Hardy to zone 6..  ( have seen them growing happily, though a bit shorter in 5b ) if the above link to Dave's Garden doesn't work.. 

No idea how they behave there but drop tons of pods.  Seedlings pop up any / everywhere in warmer places here in the States. Considered an aggressive seeder/ weedy, un- welcomed colonizer / invasive PITA  in numerous areas.. Thankful they easily fry here..

https://plants.ifas.ufl.edu/plant-directory/albizia-julibrissin/

https://www.invasiveplantatlas.org/subject.html?sub=3004

[ColdBonsai]

Very hardy. I see them here in US zone 7 that can get down to -18 C. 

[Chester B]

I can confirm zone 6 maybe even zone 5. They’re grown in Southern Ontario, Canada along with the chocolate form. Just not very common there. 
 

My house here had one when I moved in. I find the flowers are the messiest part. The pods and leaves just disintegrate. All seedlings die off in our dry summers so nonissue for me. Plus them being billed as a drought tolerant plant in my experience is totally false. I have to water in summer or it will turn yellow and lose its leaves by September. 

Edited January 11, 2022 by Chester B

[UK_Palms]

Thanks for the replies guys. Pretty much the whole continental US has warm-hot summers though too, even in areas that get freezing cold winters, so no wonder they do okay there. I think Albizia depends on a decent growing season and some summer heat too for them to actually grow well and flower properly. I wonder what the furthest north is that they range in North America and Europe? Like is there any in Scandinavia for instance, and if so, do they even flower there?

I can see why people may dislike Albizia or find them annoying, due to the messy flowers and invasive nature. I still think they are quite an attractive and ornamental tree to plant, especially in cooler, more northern regions. I suspect more and more Albizia's will keep appearing in the UK in the coming years.. I have no idea whether these grow up in Scotland or not? The growing season is probably too short up there and I doubt Scotland gets enough summer heat for it to flower properly.

[Chester B]

I think it's safe to say in North America, the most northern place these can grow, and most likely are growing in areas of British Columbia along the coast.

Yes they are attractive trees, I think they're best away from your standard garden beds where you don't have to keep picking the spent flower off all your plants.  

[ShadyDan]

Pretty sure I've seen them growing way up the coast in Haida Gwaii before. Not sure if they flower there, but I don't see why not. They are commonly grown all over Vancouver Island and do just fine here, even on the cooler west coast of the Island.

I would like them better if they were evergreen.