Nikau Palm Blues
Everything you need to know about the Shaving Brush,
or Nikau palm by transplanted Kiwi, Charles Jackson.
Charles S. Jackson, Westcliff on sea, Essex, UK
Chamaerops No.34 Spring 1999
Picutre: The bulging crownshafts of Rhopalostylis
sapida, Jim Wright's garden, California.
Rhopalostylis sapida is often considered a challenge
to grow in Europe and so, as a New Zealander, I thought it would
be useful to examine its natural habitat, climate and cultivation
requirements to assist my fellow palm enthusiasts to grow one of
the world's most beautiful temperate palms. Rhopalostylis Sapida
grows in New Zealand, its off shore islands i.e. Great Barrier Island
and also is found on the Kermadec Island group, Norfolk Island and
the rather southerly Chatham Islands.
This palm species is found nowhere else in the world
and, like most New Zealand plants, has very strange growth habits
and rather contrary requirements. Even on mainland New Zealand they
will grow in some places but will not grow in others even if the
climates are similar. This palm is predominantly a coastal lowland
tree but in favourable climates can be found growing further inland
but not far! Its southern limit on the mainland is Westport on the
very wet, mild west coast of the South Island. Why this palm will
not naturally grow further south than Westport is unclear as the
climate is very similar in Westland all the way down to Haast (Jackson's
Bay) but there must be some slight climatic or physical change south
of Westport which precludes this palm from spreading. It is planted
as a garden shrub in Hokitika and Greymouth and grows marvellously
so it can only be assumed that it must be the physical barrier of
the hills between Westport and Greymouth that prevent this palm
from naturalizing areas further south. Alternatively, it could be
a slight climatic difference as already mentioned but this difference
must be minuscule.
As for the colony of Nikau palms at Palm Gully, south
of Akaroa on Banks Peninsula on the east coast of the South Island
near Christchurch, it is not at all certain that this is a natural
population. It could very well be a remnant population from when
the Banks Peninsula and all the Canterbury plains (and virtually
all of New Zealand) were covered entirely by native evergreen, hardwood
forest. Long before the arrival of the white settlers the Maori
tribes of New Zealand had cleared by fire large areas of forest
and the Banks Peninsula tribe had, of course, done the same.
If it is a natural palm colony then this would be
the southernmost limit of a mainland population of this species
and also the most cold adapted and dryness adapted variety of Nikau
available anywhere. Although the nikau of the Chatham Islands lie
further south than the Banks Peninsula population, there are significant
differences between the climates of the two locations. The Chathams
have a temperate ocean climate that is neither too hot nor too cold.
In fact the Chatham Islands do not suffer any frosts whatsoever
but then have a great deal of cool weather to put up with. Constant
sea breeze blows at all times and frequent violent southerly storm
fronts blow through all year round.
On Banks Peninsula some of the climatic conditions
affecting the Chatham Islands are experienced by the Nikau population
in Palm Gully but the problem of frost, dry summers and strong sunshine
are added to make life for these palms considerably more difficult.
Nevertheless, they are probably the best and most robust type of
Nikau to be found in mainland New Zealand. Seconded only by the
West coast South Island type, closely followed by the type found
near Gisborne (East coast, North Island) and the superior type found
on the Great Barrier Islands (Northeast of Auckland).
Regarding whether the Banks Peninsula Nikau palms
are naturally occurring, it may never be known. It has been suggested
that the Maoris, when they migrated south from the North Island,
brought seed of palms with them to grow for their own use. It has
also been suggested that these palms were planted in the massive
reforestation programme undertaken by Christchurch Botanical Gardens
and Christchurch University at the beginning of this century. It
is interesting to note that the New Zealand people were vigorously
encouraged from the 1880's onwards, in various campaigns, to go
out and replant as much native vegetation as they could to help
restore New Zealand's beauty after the terrible ravages of the Maori
bush fires. Anyway, the Nikau population at Palm Gully, exists and
survives brilliantly, and does not seem to be bothered too much
by the colder conditions or even the occasional snow cover on the
high volcanic peaks of Banks Peninsula and Port Hills which overlook
Christchurch and Lyttleton Harbour.
Regarding Nikau's adaptability to different temperatures,
it is very evident by examining trees in different locations and
at different latitudes that these palms do not like hot climates
or strong ultra violet light. As you move further north in New Zealand
the quality of the trees deteriorates somewhat, from the good specimens
found around cool Wellington, the capital, to Auckland and North
Auckland where they are the poorest type specimens seen anywhere
in New Zealand. Auckland and further north have a warm temperate
climate with very strong sunshine leading to rather a harsh environment
which sustains mangrove swamp and coarse, woody vegetation and sustains
tree ferns and Nikau palms only where it is shaded, sheltered, cool
As you examine the Nikau palm population going south
to the cooler climates, you make a rather interesting discovery.
The Nikau's fronds open out more and more the further south you
go starting with the Auckland /Northland type which have the most
upright fronds (possibly to protect themselves from too strong sunlight).
Further south are the noticeably more beautiful southern type from
the southern North Island and the South Island whose fronds open
out to a full 45° angle. There are exceptions to this rule as
the Gisborne and Great Barrier palms have fronds that open wider
than other near populations. It is also worth noting that even the
Norfolk Island and Kermadec Island Nikau's have more open fronds
even though these islands are in the sub tropics but due to their
oceanic cool, cloudy climates they sustain Nikau growth better than
the majority of northern New Zealand.
It would be interesting to find out whether the Nikau
was indigenous to New Zealand before the Maoris arrived or did they
in fact bring this palm with them from Norfolk and Kermadec Islands?
I believe that the Nikau was already there and had been for many
hundreds of thousands of years. Perhaps there is ancient fossil
evidence in New Zealand showing Nikau frond impressions from thousands
of years ago. The differences between the island Nikau and the New
Zealand mainland type are significant enough for me to think that
they have always been different populations.
The Maoris found this tree very useful for all sorts
of purposes. It must have been a godsend to them that their new
land was endowed with such a beneficent tree or that the tree they
had brought with them from the Pacific Islands could indeed grow
in this rather cold, wet southern land. Anyway, this is besides
the point - the Nikau is there, and in a myriad of shapes and sizes.
It is truly the most temperate of all palms and this means that
it dislikes heat and equally dislikes cold and will only succeed
naturally in the most temperate range of latitudes (3O°S to
44°S). It is planted as a garden tree elsewhere in New Zealand
outside these latitudes but it can be risky as heavy frosts precludes
any cultivation. The only exceptions I know of are at the mild Glen
Falloch Gardens on Otago Peninsula at Dunedin and , of course, at
Greymouth and Hokitika in west coast, South Island where heavy frost
is not normally a problem.
Dryness of climate is also a great limiting factor
that makes it impossible to grow Nikau palms in my home town of
Timaru, Canterbury province or indeed in Christchurch the provincial
capital. Added to the dryness of the Canterbury climate is the relentless
heavy frost experienced every winter that would decimate a Nikau
population but tends to have no effect whatsoever on the local Phoenix
canariensis population. Dryness and frost are also what precludes
Nikau from spreading to inland New Zealand and in north Auckland
the very salt laden sea breezes put pay to any chance of Nikau surviving
in any decent looking state at all.
As for the Nikau palms requirements for cultivation,
it is advisable to examine its various habitats. Firstly, they are
deep shade forest trees which spend most of their lives under the
high evergreen canopy of the native forest where they will experience
no sunshine (Nikau palms burn even in dappled sunlight when immature),
little wind and no frost at all. They grow in very moist rich leaf
litter on the forest floor and don't mind even if the soil conditions
are boggy. Some Nikaus live and survive quite happily in low scrubby
na tive bush between 6 - 12 ff in height and, when young, are cushioned
from the elements in the same way as the deep shade forest trees
but in this short scrub they seem to have to grow, harden and mature
much more quickly. Environment-wise, Nikau are awkward but reasonably
adaptable even though it seems begrudgingly. True, the immature
deep shade forest palms are impressive - deep green foliage, huge
juvenile fronds both tall and wide but their scrub grown counterparts,
which have to maintain much smaller immature dimensions so as not
to overdo their exposure to the elements and damage themselves,
are just as impressive.
Nikau palms are slow growing and this can sometimes
be an understatement as generally the mainland type in cultivation
will manage just one frond a year - two if you are lucky. The Island
species, be it Norfolk, Chatham, Kermadec or Great Barrier are indeed
faster growing - the Chatham Islands type probably winning this
race outright. It is said that they start growing a trunk around
15 years of age shortly after having started to produce the first
of the adult fronds. Nikau do have two frond growth stages - juvenile
fronds which are not hardy to frost, sunlight, wind, and the fully
fledged adult fronds which are produced prior to reaching an exposed
level in the forest or breaking through the overhead bush.
These palms are literally tortoises of the palm world
and I would think it lucky to get a trunk on a tree at 15 years
of age. It is more likely that you will have a proper Nikau looking
palm tree at the age of 30 years at which time it will also flower.
I have a friend who collected seed of an Auckland Nikau type and
germinated it here in the UK in 1985 and his Nikaus are even now,
in 1999, still only half the size required for trunk formation.
It does depend, of course, on the environment you give your plants
but even so the rate of growth is painfully slow. The large trees
that are seen growing in New Zealand are perhaps 30 - 40 ft tall
and must be in the region of 80 - 120 years old. By the time they
reach this maturity there is nothing adverse that the New Zealand
climate can throw at them that will do any harm at all.
Once a trunk is formed then growth does speed up and
these trees seem to be able to adapt their growth rate accordingly
to the height of forest canopy or scrub above them. Growing in short
scrub they mature earlier - in deep forest they mature slower. However,
don't make the mistake of thinking you could get your own Nikau
to mature earlier if you move it out to a much brighter position.
As juveniles they must at all times be in the shade with no sunlight
at all. They must have a good level of light and dislike total shade
but will withstand deep shade as long as the period of light is
lengthy. My own experience has shown that they must be grown just
like a maidenhair and have the exact same requirements of cool conditions,
moisture, free air movement and no sunlight.
It is not a good idea, generally, to grow Nikau in
hot houses as they can not cope with hot, humid tropical conditions
and will simply cease growing. They can however be grown in a cold
greenhouse with much ventilation in summer and considerable shading
of the glass overhead. Not only, as mentioned earlier, will juvenile
Nikau burn badly in sunlight but they will also be badly affected
if there is too much bright light generally. When this happens they
will go yellow and stay yellow in growth unless further shading
is provided. Good air movement is essential for both juvenile Nikau
and mature ones alike. It has been shown that the Island type of
Nikau is superior to the normal type and this makes me believe that
the flow of moist fresh air around the island plants is essential
to their well being. So this must be provided when growing them
indoors or in a greenhouse. Stagnant air will kill Nikau palms as
it leads to mould, rot and general deterioration of growth and health.
Nikau palms are also prodigious feeders, and I have found that they
respond well to "Tomorite" tomato food and top dressing
of fish, blood and bone. This greens up the fronds to a good deep
colour and also works well for all other species of palm.
Finally, although this article may portray the Nikau
as a challenging palm to grow, please be assured that even though
they may be peculiar, they are certainly not difficult trees to
cultivate, and when larger are one of the most beautiful palms you
can grow. They are absolutely perfect for indoor cultivation away
from central heating and sunlight. Remember treat them like a fern
and you will have no problems, and please also remember that it
is unlikely that you will be able to grow this tree outdoors in
your garden in the UK until fully mature or unless you live in a
very warm, sheltered part of the British Isles where frost is almost
never a problem.
18-03-19 - 14:03GMT
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