Thuja occidentalis 'Rheingold' / Rheingold Arborvitae

Thuja occidentalis 'Rheingold' is one of the most popular selections of Arborvitae in the nursery trade. It is distinctive when young through its dense globose form with coppery-yellow juvenile foliage. In summer, the color is more golden-yellow, while winter brings out the strong coppery overtones. It's best color develops when planted in full sun.

With age, plants will develop more adult-type, scaly foliage and assume more of a broadly upright structure. After 10 years, a mature specimen will measure 6 feet (2 m) tall and 4.5 feet (1.5 m) wide, an annual growth rate of 6 to 8 inches (15 - 20 cm). It's size and structure is easily controlled though annual shearing. If an older plant gets to the point where the adult-type foliage becomes overly dominant, it should no longer be considered an example of 'Rheingold;' rather it should be considered to have reverted into its parent form, 'Ellwangeriana Aurea.'

This cultivar originated as an exceptionally stable, juvenile-foliage branch mutation, found around 1900 on a specimen of Thuja occidentalis 'Ellwangeriana Aurea' by Rud Vollert, a nurseryman from Lübeck, Germany. Apparently such mutations are quite common on "Ellwangeriana-type" arborvitae with differences mainly in stability. It is reported that propagating adult-type foliage from 'Rheingold' will still result in juvenile-foliage, suggesting its unique DNA.

Also noteworthy is that nearly every reference in print states that 'Rheingold' was a seedling selection. Given that it was introduced over 100 years ago, this claim is impossible to confirm or refute. This reference claiming that it originated as a result of branch mutation is based on common sense and observation.

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Attribution from: provenance based on a Facebook (Planet Conifer) discussion on July 8th, 1016 between the ConiferBase Editor; nurseryman, James Wick of Tennessee, USA; and nurseryman, Edwin Smits of Volkel, The Netherlands .

Thuja occidentalis 'Rheingold' — a mature specimen in an arboretum setting.
Photo by Ken Church
Thuja occidentalis 'Rheingold' — a closeup of foliage detail.
Photo by Sandra McLean Cutler
Thuja occidentalis 'Rheingold' — photo copyright of The Wildlife and Conifer Garden, donated by Don and Nonda Surratt, Ohio, USA.
Photo by Nonda Surratt
Thuja occidentalis 'Rheingold'
Thuja occidentalis 'Rheingold' growing in central Maine since 2010.
Photo by Wynne Keller

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