Re: Rhodos in N.Z.

Einionygarddwr@aol.com wrote:
> 
> Dear Tony & Moira,
> 
> Hello again. I seem to recall that our last correspondence was on ericas, but
> I now move on, although in the same family, to rhododendrons. You will have
> seen Michael Barclay's message a couple of days ago about vireyas; I've since
> been in correspondence with him, and I happened to mention the display of
> them in the greenhouses at the Royal Botanic Gaden, Edinburgh. In his reply
> he says that, impressive though the Edinburgh collection is, the best
> collection of vireyas he's ever seen is the Pukeiti Rhododendron Trust garden
> in New Zealand. He says that there they are grown outside, so I assume that
> this is North Island, being warmer? (I'm assuming that you know, or at least
> know of, this garden). Here, of course, they can only be grown under glass,
> although the couple of specimens which I have so far do get put out over the
> warmest months of summer. On the other hand, the maddenii series are a
> realistic possibility outside, at least for those of us on the west coast of
> Britain. Interesting that, as far as the winter survival of plants outside is
> concerned, there is a far greater difference between east and west than
> between north and south. Is there anything like that in NZ, or is the
> difference between the two islands the crucial factor? (As an aside, I find
> it very annoying, as do other gardeners here who are interested in the NZ
> flora, that the most glamorous plants seem to be those from the North Island,
> and therefore the least hardy!)
> 
Dear Einion 

Yes, I know Pukeiti well. It is a world class Rhododendron collection.
In fact I understand it is classed among the two or three finest on the
globe. 
It is situated in the west of North Island on the inland side of
Mt. Taranaki (Mt. Egmont on older maps) a dormant volcano very like
Fujiyama in appearence.

The climate it enjoys is both mild and rather uniformly moist with mist
off the mountain as well, so that both Rhododendrons and associated
vegetation
grow superbly.

I haven't visited for some years, but when I was last there a good part
of the Vireya collection was in fact housed under glass, though without
any heating. However, I think they were largely at the exploratory stage
at that time and I have no doubt that most are now outside. Even though
our local climate just here is borderline for them, there are some areas
in the main Lower Hutt valley where they grow outside if sheltered under
trees. Wainuiomata is a unique suburb of this city, situated in its own
valley up in the hills and is just that much colder in winter that I
wouldn't risk my collection in the open garden, but they are grown in
pots and permanently housed on a terrace which is simply roofed over
wire clear plastic sheets for the benefit of a large grapevine. In
summer the vine gives the Rhodes some welcome shade and in winter the
roof prevents the temperature dropping much below freezing, which seems
to suit them nicely. 

I love the way they flower at all sorts of seasons. It is mid autumn
here and we are enjoying a succession of flowers from several of them.
As I write I glanced out the french doors and saw a new one out, so went
to have a look. Though still very small it has one truss open and two
more nearly out. The name is Haloed Gold and it is fairly deep primrose
yellow.

As to the NZ climate there is no simple way to describe it, but although
the country has much the same area as Britain the situation is so
different that the sort of weather we get bears little resemblence to
yours.

The main differences are certainly due to the fact that while Britain is
so close to continental Europe NZ is composed of true sea islands, nor
do we have any sea current as climate-influencing as your Gulf Stream.
We are also at a lower latitude than you, Wellington on southern tip of
North island is
almost exactly in the centre of our very long land and its antipodes is 
Madrid. We are just at the latitudes to be in the path of the Roaring
Forties -those  winds which sweep almost unchecked around the southern
ocean.

This situation gives the North Island  generally a more evenly temperate
climate than yours, with a tendency to warmer minimum temperatures but
slightly cooler summer maximums and with also a marked tendency for the
rainfall to diminish from  west to east. As one would expect the far
north of this island (nearer the equator) is a good deal warmer than the
far south. Most areas south of Auckland experience mild to moderate
occasional winter frosts with snow on the higher hills and occasional
transient falls even down to sea level. The long peninsular which runs
north from Auckland though is known as the Winterless North and
certainly the very occasional frost in some of its districts seems to
catch every gardener and his hibiscus tree by surprise.

Although as I have indicated this island does get westerly rain the
drier eastern districts actually  get their main precipitation from
winter southerlies sweeping up from the South Pole. This gives a climate
with close to the mediterranean pattern of cool wet winters and warm dry
summers and indeed many parts of the east coast do very well with
mediterranean plants.

The South Island has a much more extreme climate due partly to its more
southerly situation but far more to the effect of the quite considerable
mountains (the Southern Alps) which run close to its western coast and
noticeably interrupt the rain bearing westerlies as they sweep by. This
divides the island into a narrow west coast plain with a mild oceanic
climate coupled with a very high and well-distributed rainfall, and a
much wider plain east of the mountains  (and in their rain shadow) which
can be fiercely hot in summer with dry foehn-type winds coming off the
mountains and very cold in winter with heavy frosts and considerable
falls of snow. 

The westerlies strike the North Island as well, but with less strongly
marked features than the southern mountains to intercept them, the
rainfall they shed is generally much less even in western districts.
However, with the help of Mt Taranaki, Pukeiti and the surrounding
countryside does manage to collect a good share with a fairly regular
distribution throughout the year, which I guess is what makes it so
perfect for growing Rhodos!

As to the geographical relationship of the two islands, though known as
North and South they are well on the way to becoming East and West
instead due to the fact they are both poised on the boundary between two
of the world's tectonic plates which apart for engendering occasional
large earthquakes is also causing the South Island to travel steadily
north so it is already overlapping the North Island by quite a bit. This
causes Cook strait which separates the two to actually run almost north
and South. 

This deep narrow strait is a notoriouis wind funnel and adjoining
districts on both coasts really know what winds are, especially through
spring. Gale and even storm force winds are well known to us who live
around Wellington and our houses are designed and our gardens planned to
cope with tehm, so there is only the really exceptional blow every
twenty years of so that can cause serious disruption. At least they are
farly steady winds and we are lucky to escape the much more destructive
tropical cyclones, which have never yet come come quite so far south.

An interesting and bracing climate to live with!!

Moira

Tony & Moira Ryan <theryans@xtra.co.nz>
Wainuiomata, New Zealand. (on the "Ring of Fire" in the SW Pacific).
Lat. 41:16S Long. 174:58E. Climate: Mediterranean/Temperate
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