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From Far East to Alps
Some preliminary remarks
on acclimation of tropical camellias
in northern Italy
Gianmario Motta
(Pavia University, Italy)
Professor, Vice President of ICS (Europe),
[email protected]
1 The acclimation issue
From two centuries Camellia japonica acclimatized
throughout Italy, from Alps down to Sicily. It
is so happy that it freely self­-seeds. A similar
naturalization was also successful with some
mountain species from China and nearby areas,
such as Osmanthus heterophyllus, Trachycarpus
fortunei (that is becoming a silvicultural pest), and
camellias such as C. reticulata, C. saluenensis, C.
yunnanensis, and some rarer species such as C.
yuhsienensis, that you can see here in full blossom
in Villa Motta [4]. Densely camellia­ populated
areas include the surroundings of Geneva, the
countryside of Tuscany, and various areas in
southern Italy, such as Naples. Among these,
the areas most densely ­populated by camellias
are the sub­alpine lakes, 59 kilometres north of
Milan. They include, west to east, the lakes Orta,
Maggiore, Lugano, Varese, Como, Iseo and Garda.
Here, especially on Lago Maggiore, that is both
in Italy and Switzerland, camellias enjoy the light,
acid soil and the generous rainfall that together,
balance the winter. Actually, in this region, orange
trees cannot survive outdoors and the temperature
frequently drops several degrees below zero. In this
lucky region, almost every house has a garden and
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the regular plants are camellias, rhododendrons
and azaleas (magnolia and osmanthus as well).
Therefore it is of high interest to introduce new
species and varieties that can widen the range of
cultivated camellias.
We here consider the experience derived from two
groups of camellia coming from tropical areas
of China and Vietnam: the first group we call
‘maritime’ because they come from sea regions
and include C.granthamiana and C. crapnelliana,
and the second group called ‘tropical lowland’ that
includes camellias that, in my opinion, promise
the most astonishing flowers, namely C. changii,
C. amplexicaulis, and C. nitidissima, that we
consider as a champion of all yellow camellias.
For a general description of these species we refer
to the book by Gao, Parks and Du [14].
A preliminary look at the climatic data of Milan,
Naples, Hanoi, Hong Kong and Nanning, as
recorded on Wikipedia, suggests some overall
remarks. Surprisingly, humidity and rainfall
are not very different, especially if we consider
that rainfall in lake areas are generally 20 to
40% higher than in Milan. By contrast, two key
elements diverge. First, the gap in the average low
temperature in January makes outdoor wintering
really harmful even in Naples. Second, the gap in
the average high temperature might prevent shoots
from becoming woody. Based on these data, one
could assume that a conservatory or greenhouse
could allow cultivation anyway. However,
experience shows different results.
For instance, in the 1984 winter, the coldest of the
century [8, 9, 10, 11], temperatures were as low as ­20°C
in Germany and Italy; most C. reticulata plants
and their hybrids were severely damaged or lost
and while most C. japonica plants suffered little
damage, C. oleifera plants were also unharmed.
According to Ackermann, who published his
extensive research on camellia hardiness, C.
oleifera is a “source of hardiness” [16]. Thus, the
equation ‘the milder the original climate the less
hardy the plant’ was contradicted by the evidence.
The winter of 2011, although not as severe as that
one, produced in northern Italy temperatures as
low as ­15°C, and was really deadly because the
cold peak came half way through February, when
some plants were preparing to shoot.
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Camellia granthamiana
C. granthamiana was imported many decades
ago [17]. Small groups of them grow in collections
at Lago Maggiore, in Villa Anelli[2], Parco delle
Camelie[4], Villa Motta [3] and in selected nurseries
such as Eisenhut in Switzerland. Generally, C.
granthamiana, though originating from Hong
Kong, winters outdoors, and survives even the
coldest winters, if sheltered. The picture shows the
wonderful November flowers in Villa Anelli [2].
Collection
Location
Villa Anelli
Lago
Maggiore
Lago
Maggiore
Lago
d’Orta
[2]
Parco
Camelie [4]
Villa Motta
[3]
Camellia
crapnelliana
Some seeds of C.
crapnelliana
(that
comes
from
the
same region of C.
granthamiana) were
imported in 2003 from
Hong Kong. Almost
all germinated and
grew vigorously in a
greenhouse (see picture taken in 2004). In 2006
one tree of that batch was planted outdoors in
Villa Pallavicini (Geneva) [6]. It continued to grow
and flowered freely every year in autumn, rapidly
reaching the height of 1.5 meters. In 2010 the plant
was moved because of water seepage in the soil;
replanted, it is recovering. Another plant of the
same batch was planted outdoors at Villa Motta [3];
Plant
Winter 2011-12
Other winters
Adult
Unharmed
Unharmed
Adult
Young
Damaged
(exposed position)
Unharmed
(sheltered position)
Some damage
Unharmed
Remarks
Free flowering
in winter
Free flowering
in winter
Not yet
flowered
Table 1 Climate elements (adapted from Wikipedia)
Element
Average high °C
HONGKONG
25,6
HANOI
27,0
NANNING
26,3
MILAN
17,2
NAPLES
20,4
14,5
13,7
10,0
­1,9
3,8
Rainfall mm
2.398,9
1.676,2
1.309,8
943,2
1.066,6
% humidity
78,0
78,8
79,1
76,8
NA
-8,4
-9,8
-9,1
-16,4
-15,6
-11,9
­-1,455,7
-733,0­
-366,6
­-1,2
­-2.0
-2,3
Average high °C
­-5,2
-6,6­
-5,9
Average low °C January
­-10,7
-9,9­
-6,2
-1,332.3
NA
­-609,6
NA
­-243,2
NA
Average low °C January
Gap of Milan
Average high °C
Average low °C in
January
Rainfall mm
% humidity
Gap of Naples
Rainfall mm
% humidity
135
Collection
Location
Villa Pallavicini [6]
Geneva
Villa Motta [3]
Lago
d’Orta
Plant
2003
seedling
2003
seedling
Winter 2011-12
Other winters
Remarks
(indoor)
Perfectly
hardy
Free flowering
Badly damaged
(all leaves lost)
Minor damage
Not yet
flowered
it grew quite well but never flowered and it was
severely damaged by the winter 2011/­12. Now
it is recovering in a greenhouse. C. crapnelliana
marginally survives outdoors in Villa Anelli. So, it
looks to be less hardy than C. granthamiana and is
better suited to southern Italy.
Camellia changii
C. changii. The cuttings were grafted onto C.
japonica and survived, but produced only a few
flowers one or twice in one year. Most shoots were
probably affected by dwarfism. A few shoots were
able to make a flower bud and actually flowered
between June and August, after the shoot had
become woody. Most plants were lost because of
the low temperatures. In 2008 a grafted tree was
planted outdoors at Villa Motta [3] in a sheltered and
shaded lawn. The plant flowered in late October
2008 and 2009 but it was lost in the winter 2011­12 (see picture).
In 2012 Andrea Corneo [15] imported various plants.
Two plants, grafted on C. japonica and raised in red
clay, were transplanted into a blend of peat (50%)
and organic soil (50%) and stored till May indoors
in a greenhouse with a high humidity rate and a
constant temperature around 20℃. Afterwards the
plants were taken outdoors into light shadow with
drip watering. They produced vegetative growth
twice, in April and September, and produced 1­2
flowers respectively in June and November (see
the picture of the flower bud). By contrast, seeds
actually germinated but they were not able to grow
and seed plants died after three to f­ our months.
C. changii has been extensively studied by
Professor Gao, who considered also the climatic
conditions of the original environment [18]. In
2005 professor Gao Jiyin visited Italy, guest of
Paolo Zacchera (owner of the Compagnia del
Lago nursery [7]), and brought some cuttings of
Collection
Location
“Compagnia del
Lago” [7]
Lago
Maggiore
Lago
Maggiore
Lago
d’Orta
Villa Anelli [2]
Villa Motta [3]
The late Peter Fischer reported a similar experience.
According to him “plants grafted in China look
really good at the moment, with 5 cm growth after
one year. One flower developed from this growth
and now has a seed capsule”. By contrast “seeds
germinated really quickly, but after the last winter
only 20 survived and show [in August] only a
modest growth” [13].
Plant
Winter 2011-12
Other winters
Remarks
2005 graft
NA
Gradually lost
Dwarfism
2012 graft
NA
(in conservatory)
Few flowers
2012 graft
Lost
Minor damage
Few flowers
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We can therefore assume:
The annual vegetative growth does not require a
winter cycle but is continuous.
The flowers are produced after the plant has
vegetated and the new growth has become woody;
vegetation requires warm temperature; hence,
the higher the temperature the more frequent the
flowers.
The plant does not stand low temperatures even
above zero, but it does not require a lot of humidity
thus, if grafted, it could be a decorative plant for
indoors.
Grafted plants look to be far more resilient than
seed plants.
Camellia amplexicaulis
C. amplexicaulis, thanks to its wonderful leaves
and flowers, can be considered the queen of the
whole Camellia genus. The area of wild species
is very limited, only to Tam Dao Park in Vietnam
and to the Hekou County in Yunnan Province
(China) [14]. A first batch of seeds was imported
from Vietnam in 2003. A subset was distributed by
Professor Motta to FLM, a large nursery on Lago
Maggiore, which then germinated well and grew
healthily (see picture). In 2005 one of them was
planted outdoors in Villa Pallavicini, Geneva [6],
but did not survive the winter. Currently, no plant
of that stock is surviving. A second batch of seeds
was imported from Vietnam in 2007. One subset
was cared by Andrea Corneo at Villa Anelli [2]
and his house in Milan. They germinated with
a success rate over 90%. In the first year, the
seedlings grew vigorously and were able to keep
their two underground cotyledons; the growth was
about 200­-250 mm. In the subsequent years, they
grew very little and began to die. From the initial
1,500 seeds imported in 2007, only 200 plants are
surviving in 2013, with a height of only 400­-450
mm and chlorotic leaves. In winter, the plants are
in a cold greenhouse and in summer are outdoors
with aerial watering. Deaths occur throughout
the year, regardless of temperature. Every kind
of soil has been tested (heather soil, blond peat
variously drained by lapillus) and also various pot
sizes. However, the growth is unaffected even by
fertilizers and acidifying materials (as iron chelate
and iron sulfate). A similar result was obtained in
Veneto (zone 8­9) by Mr Buosi, member of ICS: of
160 plants only three survived, which grew up to
700­-800 mm.
While seedlings failed, a grafted plant of C.
amplexicaulis, that was imported by Andrea
Corneo from Japan in 2010, flowered in May
2012. So far, it is surviving well indoors in Villa
Anelli [2].
Apparently, also soil plays a role. In Vietnam plants
grow in red clay, probably with a high rate of iron.
In Italy we use acid peat for pots, while outdoor
soil is acid and derives from the decomposition of
volcanic rocks such as granite, basalt, gneiss and
alike, with a high rate of silicates. As evidence
shows, the only flowering plant is a grafted one,
while the six years old seedlings look neither
healthy nor ready for flowering.
137
Collection
Location
Plant
Villa Anelli
Lago
Maggiore
Graft
2010
Seedling
2003
Seedling
2007
Seedling
2007
Villa Pallavicini [6]
Villa Anelli
Buosi
Geneva
Lago
Maggiore
Veneto
Camellia nitidissima
Winter
2011-12
Other
winters
Remarks
Indoor
Indoor
Few flowers
NA
Lost
outdoor
No survivors
NA
NA
NA
NA
Raised in greenhouse;
marginal survival rate
Raised in greenhouse;
marginal survival rate
2 Conclusions
We have illustrated experiences of acclimation
of some tropical camellias. Though the sample is
limited and the area studied includes only the lake
region of northern Italy, some elements emerge.
First, species behave regardless of their climatic
origin, as we summarize here below. Second
grafted plants promise a better performance, but
flowering is still shy. Further analysis on soil,
moisture and other elements is needed to enable
the use of such wonderful camellias as an indoor
plant for apartments.
Acknowledgements
C. nitidissima has been widely hybridized and
cultivated. Though second and third generation
hybrids are reasonably easy, they lack the charming
yellow that is typical to the true species. So, several
attempts have been made with the true species.
Among them, a plant grafted on C. japonica, was
raised in Orto Botanico (Botanic Garden) at Lucca
[3]
from 2006, by Mr Lippi, an ICS member. The
plant is now over 1.6 meters tall, and flowers every
year, alternating years of free flowering (over 10
flowers) and poor flowering (less than 5 flowers).
The plant is in a pot. In the current winter 2012­13 it is outdoors, with no apparent damage. This
is not surprising. Plants in the Botanical garden
of Kunming withstood snowfalls in 2004, as I
personally observed. Also, Gao states that this
species comes from relatively high elevation, up
to 950 meters [14].
However, it does not withstand direct sun. By
contrast most cuttings, though germinated, failed
to survive (see the picture of a one­year seedling).
A similar successful experience with a grafted
plant is reported in the U.K.[19]
These notes had not been possible without the
material provided by Andrea Corneo (President
of the Italian Camellia Society), Daniele Marcacci
(President of the Swiss Camellia Society), Angelo
Lippi (former director of Lucca Botanic Garden),
Davide Picchi, Osvaldo Buosi and Paolo Zacchera.
Literature cited
[1] http://www.eisenhut.ch/
[2] http://www.villa-anelli.it/
[3] http://www.ortobotanicodilucca.it/
[4] http://www.villamotta.it/
[5] http://www.myswitzerland.com/it/parcodelle-camelie-locarno.html
[6] http://www.pegli.com/villapallavicini/
[7] http://www.compagniadellago.com/
[8] Archibald, Bruce “That winter”, International
Camellia Journal, n.18, 1986, p. 79-80 (1985)
[9] Kranen G. The effects of cold winters on a
138
Netherlands Camellia Garden. International
Camellia Journal, n.18, 1986, p 80-81 (1985)
[10] Fischer P., Camellia that survived the hard
winter. International Camellia Journal, n.18,
p. 81-83(1985)
[11] Ackerman W.L., Cold hardiness studies with
camellias in North-eastern United States.
International Camellia Journal, n.18, p. 8489 (1985)
[12] Thoby C., Observations on the behavior of
Camellias in the frost. International Camellia
Journal,n.19, p. 18-24 (1987)
[13] Fischer P., German experiences with
Camellia changii / azalea. International
Camellia Journal, p.50 (2009)
[14] Gao J., Parks C.L. , Du Y., Collected species
of the genus : an illustrated outline (2005)
[15] Corneo A., Nuove specie di acclimatazione.
(New species of acclimatization), Notiziario
della Società Italiana della Camelia, Year
47th, p. 22 (English abstract p. 74)
[16] Ackermann W.L., Beyond the Camellia Belt:
breeding, propagating and growing cold
hardy camellias, Ball Publishing, Batavia,
Illinois (2007)
[17] Schoentag H., Roeder C., Discovery and
Worldwide Distribution of C.granthamiana.
International Camellia Journal, p. 83-88
(2008)
[18] GaoJ., Huang W., Liu X., Camellia changii,
the Everblooming Camellia. International
Camellia Journal, p. 89-97 (2008)
[19] Bleaney P. My experience with the golden
Camellia chrysantha (HU) Tuyama.
International Camellia Journal, p. 99 (1990)