A universal scale (to be known as the BBCH scale) using a decimal code for the description of the growth stages of most agricultural crops and weeds is proposed. The scale and codes are based on the well-known Zadoks code for cereals.Developmentally similar growth stages of different crops are given the same codes. The general scale provides a framework within which more specific scales for individual crops may be constructed. The uniformity of the scale makes it easy to remember and use in agricultural practice and simplifies storage and retrieval in a computer system.A description of the general scale is given followed by specific scales for cereals, rice, maize, oilseed rape, field beans, peas and sunflower. Comparisons with scales currently in use are given where appropriate.

Following the introduction of the general BBCH scale, the specific BBCH scale for the upland cotton plant is presented which provides crop‐specific descriptions and detailed assessment instructions. The development process of the plant is described by periods (principal growth stages) and steps (secondary growth stages). A 2‐digit decimal code suitable for data processing in crop production experiments is assigned to each step of development.

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