Anthony ”Tony” Shammarello started breeding rhododendrons in Ohio after the exceptionally cold winter 1938-39, when temperatures fell to -32°C with no protective snow cover, destroying almost his whole nursery stock of about 1500 rhododendrons. Only 300 frost-damaged shrubs survived. As a result, he set out to develop super-hardy compact rhododendrons for gardens in north-eastern USA, using as parents plants which had survived the extreme cold. Shammarello’s hardiest achievement was ‘King Tut’, which has flowered after a winter reaching -37°C. It has genes from Smirnow’s rhododendron (R. smirnowii) and from the Catawba rhododendron (R. catawbiense), among others, improving its hardiness.
Using ’King Tut’, Shammarello continued his crossings, using pollen from the yak rhododendron R. degronianum subsp. yakshimanum), among others. From these crossings he named a total of seven magnificent low-growing varieties, the best-known of them being ‘Yaku Queen’.
The red buds of 'Yaku Queen' open to pink flowers in early June, the colour gradually changing to white. In July the shrub is covered in creamy, furry new shoots. The leaf undersides are covered with a red-brown indumentum, which helps them survive dry spells and repel leaf-eating insects. ‘Yaku Queen’ has a dense habit and reaches less than a metre in ten years.