The Royal Horticultural Society Colour Chart is the standard reference used by horticulturists worldwide for recording plant colors. Resembling a paint chart, it has 920 colors which can be matched precisely to flowers, leaves, fruits and other plant parts in order to record and communicate colors accurately across the world. Each color has a unique number and letter code as well as a name.

The American Hosta Society encourages the use of this chart, if possible, for the identification of leaf, flower, petiole and other plant parts during the registration process.

This 6th edition (2015) of the chart replaces the 5th edition (2007). It has 24 new colors and every color now has an English name. The colors are arranged in four fans, housed in a sturdy plastic box with an instruction booklet in English, Dutch, French, German, Japanese and Spanish.