Lackner‘s Letter

Dear Chamaerops,

We have recently moved into our new house and we’re just conjuring up a tropical paradise in the garden. As far as my palms are concerned, everything is fine. The Washingtonia robusta looks splendid, as does my „large“ Jubaea (5 foot).
I purchased more than 30 bamboo plants in an Italian bamboo centre and planted two quite long hedges with these. I also bought the following species:

Phyllostachys viridiglaucescens
P. vivax aureocaulis
P. nuda localis
P. bisettii
P. aureosulcata aureocaulis
P. aureosulcata spectabilis.
A friend of mine will also give me some of his black bamboos (P.nigra).

All these types are exceedingly hardy and should not require any protection even during the most serious of winters.

Additionally I have planted some palms and other exotic plants already:

3 Trachycarpus takil (60 - 80 cm)
1 Trachycarpus wagnerianus (130 cm trunk, 200 - 220 cm total height)
1 Chamaerops humilis var. cerifera (50 - 60 cm)
2 Butia capitata (150-160 cm, very stiff and tough leaves and a thick base)
2 Camellia japonica
2 Viburnum tinus.

In the next few weeks they will be followed by Albizzia julibrissin „rosea“ (170 cm), Musa basjoo, and various Yuccas (Y.baccata, Y.gloriosa, Y.gloriosa >Variegata<). Can Albizzia be planted close to a house, or do they have strong roots which could cause havoc at the cellar?

I’m still thinking of planting out my large Sabal minor (150 cm) and Nannorrhops ritchiana (green form, 100 cm height, with one side-shoot already). Although the green Nanny should be hardy enough, it is the only one of this size I have and that’s why I still hesitate.

Nannorrhops „arabica“:

My Nannorrhops „arabica“ are still exceedingly blue-white and my largest plant is already 30-40 cm in height with 3 divided fans. I think it will become much larger this year. They are growing really fast with heat. By means of email I got in contact with someone from southern Austria who has visited this area where Nannorrhops arabica grows (he said it is called East-Hormozgan-Highland). His wife is from Iran and he made some scientific tests in this area and therefore he needed exact weather data, which he passed to me. Allegedly the AVERAGE LOW where these Nannies grow is -22°C (!!!!!!!), whereas the average high is +43°C. If you’re interested in more detailed data, this is what he wrote to me (translated from German):

Town: Zahedan
elev: 1373 m
average day temp: 26,5°C (year)
average night temp: 9,6°C (year)
average absolute min: -22,0°C
average absolute max: 43,0°C
mean annual temp: 18,1°C
prec:: 83 mm
days with frost frost: 56.

He wrote that in this area a wind from Afghanistan -Pamir occurs, which they call the „cow-killing-wind“. It occurs nearly every year in winter and with it the temperatures fall rapidly from 0°C below -20°C. And with strong wind this can last up to 3 days. The cooling is so enormous that a large lake (Hamoun) receives an ice-cover up to 10 cm thick. He also said that in this area Nannies (called Daz-palm by locals) with blue colour grow which have a height up to 2 meters. I have no idea where this area is. I do not have a map from Iran where I can see these details. But I’m sure you can tell me whether these statistics are true. Are they ?

Robert Lackner


Dear Robert,

Zahedan is in the south-east of Iran close to the border with Pakistan. Nannorrhops does indeed grow in this area but the information you got on the temperatures there sounds just a little too good to be true. I have precise climatic data from a town called Seistan just north of Zahedan at 610m a.s.l.:

average annual maximum: 28,3°C
average annual minimum: 13,3°C
absolute minimum: -11,1°C
absolute maximum: 48,3°C
mean annual temp: 20,8°C
precipitation: 80 mm

As you can see the data are very similar, the slightly higher temperatures at Seistan resulting from its lower elevation, but the absolute minima differ vastly (it must be the absolute minimum, not average absolute minimum as you say, as that would be even more unbelievable). This leads me to believe that the absolute minimum at Zahedan (the lowest temperature ever recorded there) is no lower than about -16°C. Not bad either, really. However, please also take into account that the cold spells there only last for a few days, that the climate is VERY dry and that the average maximum in January there is about 10°C in the shade, at least twice that in the sun where Nannorrhops grow, so on a regular day plants can warm up considerably during the day. This is a very different climate from ours in Europe and plants will have to be tried outside here before one can say how much of our winter weather they are able to survive. TS


Dear Chamaerops,

Thanks for your answer. These data sound quite reasonable if you take the latitude of this place into account. And the average low was certainly a misinterprtation of mine, because the -22°C were marked as T min and not as „Æ T min“. The reason why I interpreted it wrong was because Bernhard wrote „It occurs almost yearly in winter, that the temperatures drop quickly from around 0°C to below -20°C“ and „These temperatures occur regularily“. Because of the word ”yearly” I considered the T min to be the average absolute minimum and not the absolute minimum. So this is EXACTLY how I received the climatic data:

Town: Zahedan
elev.: 1373
Æ day T: 26,5
Æ night T: 9,6
T min: -22,0
T max: 43,0
Æ year T: 18,1
prec.: 83
frost x: 56

But what sounds a bit strange is that Bernhard wrote: „The cooling is so enormous that a large lake (Hamoun) receives an ice-covers up to 10 cm thick.“ That doesn’t sound like it’s warming up during the day too much, but I don’t know where he has the data from. The dangerous thing about weather statistics is that they can easily be misinterpreted if not studied carefully. Just take the „average annual maximum“ you wrote. I know that it means the average day temp, but it could also be interpreted as the average maximum over a number of years. But that wouldn’t correspond with the other data, especially the mean annual temp. Anyway, Nannorrhops ritchiana and the „Iran“-form are interesting palms. And even if the Iran-Nanny is not fully hardy it is certainly the palm with the most beautiful colouring I have, because its blue-white is even more intese than that of Brahea armata.

Best wishes, Robert Lackner


  28-01-23 - 22:49GMT
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