Norwich — With a special permit and site development plan approvals now in hand, advocates of the Chelsea Gardens botanical garden plan to launch a major capital campaign to raise the $20 million needed for the first phase of the project on 80 acres at the edge of Mohegan Park.

The Commission on the City Plan Tuesday approved the special permit and the site development plan, temporarily waiving any performance bond until the nonprofit foundation can raise enough money to actually start the project.

The first phase would include the main entrance on Wilderness Road, ticket booth, bathrooms, a year-round butterfly pavilion, dining emporium that could host catered events, an English gardening school and a maintenance building, along with gardens, a waterfall and paths that would use decades-old trails through the property.

Chelsea Gardens President Hugh Schnip said the group next will write a business plan for the project and then will approach major grant foundations as well as lending institutions and the general public for donations.

Chelsea Gardens leases the 80-acre site off Judd and Wilderness roads from the city at no cost.

— Claire Bessette