Abstract: A method of determining the viability of a rhizome comprises the sequential steps of: (a) sampling material from the rhizome; (b) contacting material sampled in step (a) with an effective amount of a formulation comprising a first viability indicator; and (c) observing the action of the first viability indicator on the sampled rhizome material, to determine the viability of the rhizome. The method may further comprise one or more additional sequences involving the additional steps of: (d) contacting material sampled in step (a) with an effective amount of a formulation comprising a further viability indicator different to that used in step (b); and (e) observing the action of the further viability indicator on the sampled rhizome material, to determine the viability of the rhizome. In this way, an overall assessment of the viability of the rhizome can be made based on the action of a plurality of viability indicators, each relying on an interaction with different reagents in the plant cells.