Plant of the month: Sequoiadendron giganteum

Sequoiadendron giganteum are remarkable trees that are native to a small region in central California, where they can grow to over 80m tall with a girth of over 8m. Although not the tallest trees on earth, they are the largest by mass and are among the oldest, as they can live for over 3,000 years. They typically grow at altitudes between 1,000m and 2,000m, where summers are warm and dry, and winters have reliable snowfall.

The giant redwood is now a familiar tree in cultivation. However, back in the 19th century, when news of the giant redwood groves in California was spreading, the race was on to become the first to grow them outside of the US and introduce them into cultivation. An estate in Perthshire, owned by the father of a gold prospector, was in fact where the first seeds of a giant redwood were sent in August 1853 to be successfully propagated. In December of the same year, a nursery in England was wrongly credited with this achievement; it has since been recognised that the Scottish introduction occurred four months earlier.

Despite the difference in growing conditions from their native range, the giant redwoods seem to be enjoying the Scottish climate. Many of the biggest specimens in the UK are found in Scotland, with fine examples growing in other National Trust for Scotland gardens, such as Geilston and Craigievar, as well as Holmwood. Because giant redwoods have grown in the UK for less than 200 years, it’s not yet known what size they will ultimately reach here.

Common names for these trees include giant tree, giant sequoia, Sierra redwood, mammoth tree and Wellingtonia, although giant redwood is perhaps the best known. It can sometimes cause confusion when the same common name is given to different plants, and this is the case with ‘redwood’. The name is shared with two closely related tree species: the coastal redwood (Sequoia sempervirens) and the dawn redwood (Metasequoia glyptostroboides). All three sit within the cypress family (Cupressaceae) and each is a monotypic genus (the only living species within the genus). They may look similar initially but they are quite different on closer inspection.

One of the most recognisable features of the giant redwood is its thick, fibrous, reddish-brown bark, which is spongy to the touch. The insulating properties of the bark have evolved to protect giant redwoods from forest fires in their native habitat.