Vice-chairman Chris Harbey said the business started in 1908 as a co-operative growers' marketplace for the Vale of Evesham.
He added that the firm nearly went out of business twice but survived and is now a successful limited company.
The company has been known as BHGS since July 2001 following the amalgation of two horticultural companies in Worcestershire, Littleton & Badsey Growers and GMS Requisites.
The company now has a £7m turnover and 1,000 customers. Every shareholder received an engraved steel trowel to celebrate the centenary.
BHGS is a supplier to ornamental, vegetable, salad and fruit growers. The firm is an agent and distributor for all major horticultural manufacturers including Sinclair, Scotts, Sankey and BPI Visqueen.