From Far East to Alps:
Some preliminary remarks on acclimation of tropical camellias in Northern Italy

Gianmario Motta*
Pavia University, Italy

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 sows. A similar naturalization was successful also with some mountain species from China and near areas, as Osmanthus heterophyllus, Trachycarpus fortunei (that is becoming a silvicultural pest), and camellias as C. reticulata, C. saluenensis, C. yunnanensis, and some rarer species as C. yuhsienensis, that you can see here below in full blossom in Villa Motta ^[4]. Densely camellia­ populated areas include the surroundings of Genova, the countryside Tuscany, and various areas in Southern Italy, as Naples. Among these areas, the most densely camellia ­populated one are the sub­alpine lakes, 50­90 kilometers north of Milan; they include, west to east, the lakes Orta, Maggiore, Lugano, Varese, Como, Iseo, Garda. Here, especially on Lago Maggiore, that is both in Italy and Switzerland, camellias enjoy the light and acid soil and the generous rainfall, that, together, balance the winter. Actually, in this region, orange trees cannot survive out door and temperature frequently drops several degrees below zero. In this lucky region, almost every house has a garden, and the regular plants are camellias, rhododendrons and azaleas (and 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 experiences made on two groups of camellia coming from tropical areas of China and Vietnam, namely a first group the we call “maritime”, because they come from sea regions, that include C.granthamiana and C. crapnelliana, and a second group called “tropical lowland”, that include 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 to climatic data of Milan, Naples, Hanoi, Hong Kong and Nanning, as recorded on Wikipedia, suggests some overall remarks. Surprisingly, humidity and rainfall are not too far, especially if we consider that rainfalls in lake area 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 wooding. Based on these data, one could assume that a conservatory or greenhouse could allow cultivation anyway. However, experiences show different results.

For instance, in 1984 winter, the coldest of the century ^{[8, 9, 10, 11]} temperature was as low as ­20°C in Germany and Italy, and most C.reticulata and its hybrids were severely damaged or lost, while most C.japonica suffered little damage and C. oleifera was unharmed (according to Ackermann, who published an 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 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 around half February, when some plants were preparing to vegetate.

Table 1  Climate elements (adapted from Wikipedia)

Camellia granthamiana

C. granthamiana was imported many decades ago ^[17]. A small flock of them grows in collections of Lago Maggiore, in Villa Anelli^[2], Parco delle Camelie^[4], Villa Motta ^[3] and in selected nurseries as Eisenhut. Generally, C. granthamiana, though originating from Hong Kong, winters outdoor, and survives even the coldest winters, if sheltered. The picture shows the wonderful in November flowers in Villa Anelli ^[2].

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 vigorous in greenhouse (see picture taken in 2004). In 2006 one tree of that batch was planted outdoor in Villa Pallavicini (Genova) ^[6]. It continued to grow and flowered freely every year in Fall, rapidly reaching the height of 1,5 meters. In 2010 the plant was moved because of a water seepage in the soil; replanted, it is recovering. Another plant of the same batch was planted outdoor in Villa Motta ^[3]; it grew quite well but never flowered, and it was severely damaged by the winter 2011­12; now it is recovering in a greenhouse. C.crapnelliana marginally survives outdoor also in Villa Anelli. So, it looks less hardy than C. granthamiana, and better suited for Southern Italy.

Camellia changii

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 “Compagnia del Lago” nursery ^[7]), and brought some cuttings of C. changii. The cuttings were grafted on C.japonica and survived, but produced only few flowers one or twice in one year. Most shoots were probably affected by dwarfism. Few shots only re able to make a flower bud, and actually flowered between June and August, after the shot had become woody. Most plants were lost because of the low temperatures. In 2008 a grafted tree was planted in Villa Motta ^[3], in a sheltered and shadowed lawn outdoor. The plant flowered in late October 2008 and 2009 but it was lost in the winter 2011­-12 (see picture).

In 2012 Andrea Corneo ^[15] imported various plants. 2 plants, grafted on C. japonica and raised in red clay, were transplanted in to a blend of peat (50%) and organic soil (50%) and stored till May in a greenhouse (with a high humidity rate) and indoor (constant temperature around 20℃). Afterwards the plants were carried outdoor in light shadow with drop watering. They vegetated 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, while seed plants died after three-­four months.

A similar experience was reported by the late Peter Fischer. 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 see capsule”. By contrast “seeds germinated really quickly, but after the last winter only 20 survived and show [in August] only a shy growth” ^[13].

We can therefore assume:

• The annual vegetation 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 dos not stand low temperatures even above zero, but it does not require a lot of humidity; thus, it could be, if grafted, a decorative plant for indoor.
• Grafted plants look are by far more resilient than seeds 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 looks very limited, if any, to Tamdao 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, and germinated well and grew healthy (see picture). In 2005 one of them was planted outdoor in Villa Pallavicini, Genova ^[6], but did not survive the winter. Currently, no plant of that stock is surviving. A second batch of seeds was imported from Vietnam 2007. One subset was cared by Andrea Corneo in Villa Anelli ^[2] and his house in Milan. They germinated with a success rate over 90%. In the first year, seedlings grew vigorously, and were able to keep their two underground cotyledons; the growth was about 200­-250 mm. In the subsequent years, they marginally grew 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 while in summer are outdoor with aerial watering. Deaths happen throughout the year, regardless temperature. Every kind of soil has been tested (heather soil, blond peat variously drained by lapillus) and also various pot sizes. However, the growth resulted 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 3 only 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 indoor 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 it is coming from the decomposition of volcanic rocks as granite, basalt, gneiss and alike, with a high rate of silicates. As a partial evidence, the only flowering plant is a grafted one, while the 6 years old seedlings look neither healthy nor ready for flowering.

Camellia nitidissima

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 tries have been made with the true species. Among them, a plant, grafted on C.japonica, is raised in Orto Botanico (Botanic Garden) of 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 potted. In the current winter 2012­-13 is outdoor, with no apparent damage. This is not surprising. Plants in Botanical garden of Kunming stood snow falls 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 stand direct sun. By contrast most cuttings, though germinated, failed to survive (see the picture of a one­-year seedling). A similar successful experience with a grafted plant is reported in U.K.^[19]

2 Conclusions

We have illustrated experiences of acclimatization of some tropical camellias. Though the sample is limited and the domain includes only the lake region of Northern Italy, some elements emerge. First, species behave regardless their climatic origin, as we summarize here below. Second grafted plant promises 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 apartment.

Acknowledgements

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/parco-delle-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 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. 84-89 (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)

* Corresponding author: Professor, Vice President of ICS (Europe), motta05@unipv.it