The Surrey-based firm will formally launch the new facility on its Plantation nursery and machinery repair workshop site in Addlestone on 26 March.
Business development director Yvette Etcell said it was an obvious progression: "We have worked with these products for a long time and a lot of our professional landscape and domestic gardening clients come to us for machinery repairs, so it seemed a natural evolution to start selling the equipment as well.
"It's a great opportunity here because our repair workshop is next to the shop, so staff can provide technical support."
Dealership accreditation will enable Gavin Jones to carry out contract services without paying a premium on the Stihl products it uses. Etcell said the firm hoped to boost business by passing that saving on to clients: "Hopefully this will make us more competitive on price and maybe attract more clients. It will certainly help us support our public sector clients who are facing Government cuts."
The firm anticipates that the shop will achieve a turnover of around £100,000 in the first year of trading, rising to around £500,000 after the third year. But Etcell said there were no plans to open any more outlets.