The council and Ventnor Botanic Garden CIC, headed by local residents John and Mylene Curtis, are "still in negotiations" but the sale is due to complete in May.
The bid is supported by Royal Botanic Gardens, Kew honorary research associate Susyn Andrews.
The CIC - in partnership with garden staff, the friends society and the local community - plans to "preserve and reinvigorate Ventnor Botanic Garden".
The CIC will initially invest between £100,000 and £150,000 in the garden. The planned improvements include better signage, more relevant information for visitors, trails and an improved education programme.
Existing Ventnor Botanic Garden staff will transfer to the CIC, which will manage the gardens under a 125-year lease agreement.
CICs are limited companies created for the use of people who want to conduct a business or other activity for community benefit.