The 600sq m facility will enable the nursery to delay flowering of its rhododendrons and make its full range available throughout the spring. The store will be completed by October/November this year and be up and running for next spring.
It will also allow plants to be stored for export and will hold eight lorry loads of stock. Viking Nurseries is one of the biggest exporters in the UK and is particularly strong in the Scandinavian market.
The nursery grows rhododendrons and conifers and a range of evergreen shrubs including pieris.
Sales manager Fabio Guizzo said: "We are trying to have a plant for each season so we can have constant sales around the year - rhododendrons for the spring, shrubs for the summer and conifers for the autumn. This is the first year we've had this strategy and it's going well."
The nursery has seen sales of 10-litre conifers grow quickly and has had a lot of interest in pieris, which sold out after the HTA National Plant Show.
It is now planning to introduce several new varieties as well as coloured labels for all its plants, which include a "grown in the UK" flag.