The present invention provides methods for improving competency of plant cells for bacterial-mediated transformation comprising contacting the plant cells with an effective amount of polyethylene glycol (PEG) for a period of time prior to transformation. The ability to store and maintain competent plant cells for transformation and tissue culture allows more efficient planning and execution of large-scale experiments by providing flexibility of peak production hours, or during unplanned disruptions in the production process. These methods are useful in preserving the viability of plant cells in various storage conditions, thus improving their competency for transformation and tissue culture.