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 Ravenea rivularis. 
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Joined: Wed Oct 31, 2007 5:52 pm
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Post Ravenea rivularis.
I know we have newer members looking for palms that can take some frost and cool winters.


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Sat Dec 30, 2017 5:12 am
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Joined: Mon Oct 23, 2017 9:29 pm
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Location: cantabria spain
Post Re: Ravnea rivularis.
Indeed!
Here´s mine at 43º N. It is 3 mts tall. It´s been 5 years in the ground plus 4 in a big pot. It brings forth 4-6 leaves a year. It loves water, that´s why it is very healthy and "kicking" in this weather.
As you can see, it is developing a trunk. So far, it has withstood -1ºC, -1,5ºC for short periods of time.
These pictures have been taken today ( max:22ºC, min: 14ºC)
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Julio


Sat Dec 30, 2017 6:27 pm
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Post Re: Ravenea rivularis.
For years they have a bottle palm like base. They seem to be fatter in climates that are not tropical.

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Sun Dec 31, 2017 3:44 am
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Location: cantabria spain
Post Re: Ravenea rivularis.
As I said in a thread related to trees, for those people who have gardens on the south coast of England, Ireland, Wales and inner London, they should give a try to not so hardy palm trees such as Howea, Archontophoenix, Arenga engleri, Syagrus romanzoffiana,Livistonas, Rhopalostylis and Trithrinax.
Apart from the very hardy ones (Trachycarpus, Raphidophyllum and Nannorrhops) and the hardy ones (Butia, Jubaea, Phoenix, Brahea, etc.)
The trick is to have a 40-60 mts. above sea level south facing slope, with a canopy of evergreen trees to protect those palms.
Canopy makes a difference of more than 4-5 degrees with sorrounding spots.

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Julio


Sun Dec 31, 2017 12:33 pm
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Location: North Thames delta UK
Post Re: Ravenea rivularis.
Julio

Pretty well all those palms you mention have been tried over the years. There are a couple of main issues as to why why they are not widespread. We generally don't get hot enough summers for a lot of them to be able to grow (more accurately heat degree days, but that is complicated!). Nevertheless a lot of people have tried. The main reason is that many experimental plantings were killed off by a run of cold winters a few years ago. Places along the coast that would normally not see a frost from one year to the next saw temps down to -6C or lower.
People are gradually trying again but really we are too few when you look at the country as a whole - there is no widespread established culture here for growing borderline hardy plants.

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Sun Dec 31, 2017 2:29 pm
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Joined: Fri Dec 31, 2010 10:32 pm
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Location: Brighton Sussex uk
Post Re: Ravenea rivularis.
Out of those mentioned, livistona lasted through narnia and the following years dry cold, but a cold wet spring done for it. Syagrus legged it to plant heaven from an unheated greenhouse. I have a small t. campestris which appears to not be bothered by our weather......and I'm still waiting to try rhopalostylis


Sun Dec 31, 2017 3:21 pm
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Location: cantabria spain
Post Re: Ravenea rivularis.
We haven´t got hot summers here. Average temperatures for the hottest month (august) don´t even reach 20ºC in many places. Many of these "not so hardy" palms are growing in shady and cool places, nevertheless, they keep on growing, more slowly, but growing.
There´s a brahea armata (a species that needs more heat than the others I mentioned) growing in such conditions and it´s been there for 10-15 years and only set 1 leaf every 2 years or so, but it is alive ( I´ll post a picture when I pass by).
That´s why I suggest trying these palm species, because they don´t need so much heat and they don´t mind rain in winter. What they don´t like is dry cold as you mention for long periods of time, and here comes "canopy" because it avoids them to get "fried" despite stopping growth for a time.
Those -6ºC you mention turn into "only" -1ºC or -2ºC if under canopy.

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Sun Dec 31, 2017 5:24 pm
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Location: Waimarama NZ
Post Re: Ravenea rivularis.
I have always wondered why Rhopalostylis sapida is not able to be grown sucessfully in UK microclimates shaded from excess frost. In habitat some high altitude dense forest sites would have long periods of below 10C days over the winter months, and probably rare days when the temps are not much above freezing. Growth is slow in these conditions, but at least they grow. Archontophoenix cunnighamiana seems to have identical growth requirements in NZ, and I've seen them in high altitude habitat sites where the temps are very cool all year around. In both these cases the UK frost potential is the biggest problem I suspect, rather than the cool growing season, but the frost shouldbe abletobe protected from by shading. There are lots of R. sapida sites in NZ with less heat in the summer than London, for example. But for sure other factors such as photoperiod, light intensity etc might make all the difference.

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Sun Dec 31, 2017 9:46 pm
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Post Re: Ravnea rivularis.
julrodmes wrote:

These pictures have been taken today ( max:22ºC, min: 14ºC)



that does not sound like bad winter temperatures! More like UK midsummer.

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Sun Dec 31, 2017 9:48 pm
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Joined: Fri Dec 31, 2010 10:32 pm
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Location: Brighton Sussex uk
Post Re: Ravnea rivularis.
Bennz wrote:
julrodmes wrote:

These pictures have been taken today ( max:22ºC, min: 14ºC)



that does not sound like bad winter temperatures! More like UK midsummer.

Yeah, I wish! :lol: Maybe two weeks worth, otherwise it's a sea fret, cooling wind and drizzle. Topping 20c is cause for celebration, where everyone decides it's fun to cremate some burgers or drive to the seaside(sorry, i mean sit in traffic).
I really need a 2003 summer :(


Mon Jan 01, 2018 12:26 am
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Location: cantabria spain
Post Re: Ravenea rivularis.
Yesterday´s temperatures: Min.16º-max.19º. Today´s 10º - 17º(probable max). This happens because of southern winds blowing hard and the Foëhn effect they produce.
Last December we "suffered" over 300 litres of rainfall, and cool temperatures. Averages for December here are: 13º-7º. So, these high temperatures are not usual. In summer, southern winds mean max, between 35º and 40º, and min, between 20º and 24º, but are very uncommon.
We also "enjoy" an average of 1.800 hours of sunshine a year (if lucky) which is not enough for many plants to develop properly.
Going back to "not so hardy palms". There are people on north-western coast of France (48º North) who are growing them quite easily, even Juania australis and more tender ones.

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Mon Jan 01, 2018 9:45 am
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Post Re: Ravenea rivularis.
julrodmes wrote:
As I said in a thread related to trees, for those people who have gardens on the south coast of England, Ireland, Wales and inner London, they should give a try to not so hardy palm trees such as Howea, Archontophoenix, Arenga engleri, Syagrus romanzoffiana,Livistonas, Rhopalostylis and Trithrinax.
Apart from the very hardy ones (Trachycarpus, Raphidophyllum and Nannorrhops) and the hardy ones (Butia, Jubaea, Phoenix, Brahea, etc.)
The trick is to have a 40-60 mts. above sea level south facing slope, with a canopy of evergreen trees to protect those palms.
Canopy makes a difference of more than 4-5 degrees with surrounding spots.


I'll add my specificity and personal experience to Paul's and others' comments, as I live in one of the favourable locations listed.

Archontophoenix cunninghhamia gets defoliated at -3ºC, which is an overnight winter temperature that we get most years. It won't last two successive winters. I have a seed-grown A. alexandrae in a pot, but it comes indoors when the temperature goes below -1ºC.

Arenga engleri just won't grow. It's too slow to cope with our cool summers. It just sits there and eventually expires.

I have grown Syagrus romanzoffianum from seed. It took 9 years to produce pinnate foliage - this past summer. It has a small trunk-ette. Last winter I left it out under evergreen canopy and one night at -3ºC damaged all the fronds, but it's alive and growing. This winter it is indoors. Perhaps when it's bigger I'll try again, but it will probably stay as a potted specimen, as I only have one.

Ten years from seed, several Nannorrhops ritchiana were still seedling-sized. Eventually I just planted two survivors out and they died in the first winter. It's very hardy at a decent size, but it needs intense heat to grow at all and doesn't like winter rain.

I've never grown Trithrinax, but others have kept them going for many years after starting with good-sized plants.

Brahea armata has also been grown successfully by others - not by me, although I tried. I think those who have fine plants have started with larger specimens, rather than from seed.

As Paul said, the main problem is that we have occasional winters that are far more severe than the norm, which kill off plants that have not had a succession of hot summers to develop hardened growth and good reserves.

The one supposedly tender genus that has proven itself reliably hardy in London is Chamaedorea. C. radicalis is long-term hardy here and C. microspadix has coped well with the past few not-very-severe winters. Both are very slow.

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Mon Jan 01, 2018 1:44 pm
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Location: Berkshire, UK
Post Re: Ravenea rivularis.
David Matzdorf wrote:
Arenga engleri just won't grow. It's too slow to cope with our cool summers. It just sits there and eventually expires.


That's interesting as it's often described as quite frost hardy by UK sellers so I was planning to give it a try...


Mon Jan 01, 2018 2:34 pm
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Joined: Fri Dec 31, 2010 10:32 pm
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Location: Brighton Sussex uk
Post Re: Ravenea rivularis.
Romain wrote:
David Matzdorf wrote:
Arenga engleri just won't grow. It's too slow to cope with our cool summers. It just sits there and eventually expires.


That's interesting as it's often described as quite frost hardy by UK sellers...

Either copied from US sites, or they're selling something. You wouldn't say 'buy this, it hasn't a hope in hells chance of growing where you are' would you?


Mon Jan 01, 2018 2:40 pm
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Post Re: Ravenea rivularis.
Romain wrote:
David Matzdorf wrote:
Arenga engleri just won't grow. It's too slow...


That's interesting as it's often described as quite frost hardy by UK sellers so I was planning to give it a try...


As Mark says, there's a motivation to sell plants here.

I expect it is relatively resistant to light frosts, but we've all found that cold winter temperatures are not the sole, nor even the prime determinant for what Palms will thrive in the UK. If the damned thing won't grow in summer, there isn't a great deal of value in having it survive winter.

The received wisdom is highly approximate in both directions. I mentioned that I have grown Syagrus romanzoffianum from seed. It's now about 1.5m high, including pot. I've read in several places that this sp. won't grow until the temperature reaches 22ºC. It's plainly not so: there have been summers here when we've had perhaps 8 scattered days above 22ºC, but the Syagrus motors on slowly throughout. To be sure, when we get a hot fortnight, it speeds up a great deal, but it still creeps along whenever the daytime temperature is around 16ºC or higher.

It depends what you want. If your desire is to prove you can grow a zone-pushing sp., no matter how stunted and miserable it looks, then by all means try Palms that have the headline frost-resistance to tempt the ambitious gardener. But I only want to persevere with plants that will improve the sensory experience of my garden, that make it a more visual, tactile, aromatic environment. I'll experiment with all manner of stuff - that's the whole point of my green roof - but if it struggles, won't thrive and won't reach any semblance of maturity until I'm years in the grave, sod that, I'll grow something else instead.

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Mon Jan 01, 2018 9:06 pm
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