Plant in full sun in a well-drained soil and give infrequent to occasional irrigation. Our experience with other grevillea is avoid fertilizers that contain phosphorus and to keep an eye on foliage color for signs of chlorosis that can be treated with acidifying agents or chelated iron. This plant should prove hardy to 20-25° F. 'Kings Rainbow' does great in containers or in the landscape and is a favorite of hummingbirds.

We began trialing this cultivar with Grevillea 'Kings Fire' and Grevillea 'Kings Celebration' in 2015 and noted through the trial period that these plants are strong performers with very attractive foliage and flowers. 'Kings Rainbow' has a unique bicolored flower but is the less vigorous plant in the series. In 2019 another very attractive cultivar, Grevillea 'Spirit of ANZAC', with larger bicolored flowers and grey-green foliage was added to the collection and in 2023 the beautiful orange flowering Grevillea 'Kings Sunrise' came onboard.

These cultivars are the result of a breeding program conducted by Digby Growns at Plant Development at Kings Park and Botanic Garden in Perth, Western Australia. The objective of the breeding program was the development of Grevillea cultivars that have large inflorescences with attractive colors. This series made its debut in North America through Ball Horticulture & Star Roses & Plants in 2016 and described as having "exotic looking blooms that flower year-round in Southern California.

Grevillea 'King's Rainbow' is the result of crossing a selection of Grevillea armigera with an unnamed Grevillea hybrid (G. 20101122) in 2011. The Grevillea armigera seed parent was a moderately vigorous semi-upright plant with yellow-green and dark burgundy to black colored inflorescences and the pollen parent, G. 20101122, was noted as a vigorous upright growing plant with medium red-colored inflorescences. 'Kings Rainbow was the only selected plant from this cross which received US Plant Patent PP27,931 in April 2017 and we have been growing it since 2017. 

This information about Grevillea 'Kings Rainbow' PP27,931 displayed is based on research conducted in our horticultural library and from reliable online resources. We also will relate observations made about it as it grows in our nursery gardens and other gardens we have visited, as well how the crops have performed in containers in our nursery field. We will also incorporate comments that we receive from others and we welcome hearing from anyone with additional information, particularly if they can share any cultural information that would aid others in growing it.