The authority has announced the figures during National Tree Week, which was held from November 22 to 30.
A spokesperson for the town council said: "We look after approximately 6,500 trees, which provide a habitat for wildlife and provide pleasant green settings for us to live and work in.
"Our own seedlings are grown in our nursery in Weymouth, and so far this year our team of arborists have planted 33 standard trees and 300 saplings in our parks and green spaces."
Most recently the council's arborists have worked with students at Wey Valley Academy to plant willow, alder, hawthorn and blackthorn saplings at Radipole Park and Gardens.
The authority also manages old and dying trees for the benefit of nature - leaving deadwood in place where it's safe to do so, leaving logs and prunings behind to provide habitat and leaving stumps to decay naturally, are some of the nature friendly measures used in the area's parks and gardens.
It has made a commitment to replacing every tree which has to be removed because of decay or damage by planting two in its place, the authority spokesman said.