West Sussex Growers Association chairman Graham Bryant will open the premises, which are at Poling.
The horticultural distributor completed its relocation to new headquarters near Arundel, West Sussex.
This new 5ha site is now home to purpose-built warehouse and office complex close to its former premises in Littlehampton.
Fargro is owned by its 315 shareholders, most of whom are growers. In the past six years, turnover has increased from £15million to £20 million.