"The EPS (expanded polystyrene) postal bedding plant pack exploits the key benefits of EPS - insulation and protection - providing Roundstone Nurseries with a cost effective packaging solution that has been designed to work within the Nursery's existing automated growing system".
Chris Webb, Roundstone Nurseries

For the first time plants are being grown, and posted, in the same pack straight to a customer's home. The postal pack enables Roundstone Nurseries to offer 200 different lines of bedding and patio plug plants online; more than is stocked by most garden centres.
Why EPS?
Testing
Roundstone Nurseries tested the packs by leaving plants in the postal packs for one week without opening them to provide light or water. When the packs were opened after seven days all the plants were found to be in good health - this would not be possible in any other material.
You can order plants online at www.plantconnection.co.uk