Giant sequoias outside their natural rangeShortly after its discovery during the gold rush in the middle of the 19th century, the giant sequoia (Sequoiadendron giganteum) was planted extensively outside its natural range, especially in Europe.
The success of its introduction depends very much of the resemblance of the region's climate to that up in the Californian mountains. The tree grows very well in the wetter parts of Europe like the U.K., and certain parts of Canada, Australia, and New Zealand, while it does not grow very well in the eastern part of the US or not at all in the tropics or cold areas like the northern parts of Scandinavia or Russia.
Trees can withstand temperatures of -25 °F (-31 °C) or colder, for short periods of time providing the ground around the roots is insulated with either heavy snow or mulch. Outside its natural range, its foliage suffers from damaging windburn. The tree does not appreciate too arid soils or humid, hot summers.
North AmericaGiant sequoias are very successful in the Pacific Northwest from western Oregon north to southwest British Columbia, with fast growth rates. In Washington (Seattle area) and Oregon, it is common to find giant sequoias that have been successfully planted in both urban and rural areas.
In the northeastern USA there has been some limited success in growing the species, but growth is much slower there, and it is prone to fungal diseases due to the hot, humid summer climate there. Specimen examples grow in arboretums in Pennsylvania and Rhode Island.
EuropeThe largest ones can be found on the British Isles, in southern France and northern Italy.
The giant sequoia was first brought into cultivation in 1853 by Scotsman John D. Matthew, who collected a small quantity of seed in the Calaveras Grove, arriving with it in Scotland in August 1853. A much larger shipment of seed collected (also in the Calaveras Grove) by William Lobb, acting for the Veitch Nursery at Budlake near Exeter, arrived in England in December 1853; seed from this batch was widely distributed throughout Europe.
More on the discovery of the giant sequoia...
Growth in Great Britain is very fast, with the tallest tree, at Benmore Botanic Garden in southwest Scotland, reaching 54 m (177 ft) at age 150 years with several others from 50-53 m tall.
The tallest giant redwood of England can be found in the New Forest near Southampton.
Giant sequoia in Benmore Botanic Garden (left) - Cluny House Gardens (right)
Photo by Tim Bekaert - Trish Fosbury
Not only the tallest, but also the stoutest European redwoods are found in Great Britain. One giant sequoia in the Scottish county Perth & Kinross had reached a girth of 11.15 m (37.6 ft) in 2003, another one in Cluny House Gardens (in Aberfeldy, Perth & Kinross) had a girth of 10.93 m in the same year (photo). The third place is taken by a giant sequoia with a girth of 10.6 m (measured myself in 2007) in Llangattock (Crickhowell) in Wales. In 2009 its girth had already reached 10.67 m (35 ft) .
Giant sequoia in Llangattock (Crickhowell), Wales
Photo by Tim Bekaert
In continental Europe, the tree does best in France, northern Italy, Switserland, and Germany where very large specimens can be found. In the mountainous parts of Europe around the Alps mountain range where there's plenty of rain, growing conditions for the giant sequoia are ideal.
The images above show a large specimen in Walenstadt, Switzerland (photos by Roland Beck). This tree is said to be the tallest tree of Switzerland.
This tree has a girth of 11.53 m (37.8 ft) at 1 m height. The current owner bought the parcel of ground especially for the tree because the tree risked being cut down after the sale.
This tree had a height of 48 m end 2008, was planted in 1886 and had already reached a height of 35 m in 1928. By 1961 this tree had a girth of 7.5 m at breast height and a height of 51 m. Later the tree was struck by lightning and lost its top 7 m.
Further to the southeast, to the coastal plains of the Black Sea, the tree does equally well, like in Bulgaria and Romania (probably also south of Ukraine and the Crimea, although I'm not sure about that). I saw many thriving British like giant redwoods in Bulgaria, that were doing better than they are in northwestern Europe like Holland and Denmark.
The image on the left shows a Polish giant redwood that appears to grow in sub-optimal conditions. On the right you can see a typical young giant redwood in Blaguvgrad (Благоевлрад), Bulgaria, although I saw many large specimens too of more than 100 years old.
In drier parts of Europa, like Spain, Albania, and Greece, the tree can do well provided water is foreseen during the dry summer months.
Giant sequoias have also been planted in Belgium, the Netherlands and Luxembourg.
Growth further northeast in Europe is limited by winter cold. In Denmark, where extreme winters can reach −32 °C, the largest tree was 35 m (114.83 ft) tall and 1.7 m (5.58 ft) diameter in 1976. One in Poland has purportedly survived temperatures down to −37 °C with heavy snow cover.
Australia and New Zealand
Giant sequoia in Ballarat Botanical Garden, Australia
Photo by Bill Stine
In European like, cool climates, giant sequoias do well in Australia and New Zealand and brought here by avid British gardeners. The Ballarat Botanical Gardens contain a significant collection, planted from 1863 to 1874. Giant redwoods can also be seen in Jubilee Park in Daylesford and in Cook Park in Orange, New South Wales. The latter one has a single specimen planted in about 1870.
These trees, however, are suffering from the drought which makes them more susceptible for fungal diseases.
Giant sequoia in Picton, New Zealand
Photo by Stephen Paul Hayden
Several impressive specimens of Sequoiadendron giganteum exist throughout the South Island of New Zealand. Notable examples include a set of trees in a public park of Picton, as well as robust specimens in the public and botanical parks of Queenstown.
Giant sequoia in Argentina