The first of the trees have already been planted in the raised beds in front of the Town Hall and more will be placed at others sites and in planters around the town centre, including several in large metallic planters being installed this week in the town's Market Square.
Trees selected include maple, birch (including purple birch), Japanese cedar, hawthorn, Koelreuteria paniculata 'Fastigiata', Persian ironwood (Parrotia persica), upright pine, hybrid cherry, golden Irish yew and golden-leaved elm.
Council leader Cllr Heather Scott said: "This is the latest phase in our ongoing bid to make the town centre a more attractive and pleasant environment for our residents and visitors.
"The trees will add year-round colour and interest to the town centre providing a more attractive environment for shoppers and visitors as well as a pleasant backdrop for the many events which are held throughout the year."
The move is in line with the Co Durham authority's Town Centre Strategy, approved in July, which set priorities for area for the decade ahead, including "introducing more trees, shrubs and plants".
It states: "Given changes in both the high street environment and in people's shopping habits, there is a need for all towns to develop plans that have business investment at their heart and are focused on transforming town centres into a community hub offering health, housing, arts, education, entertainment, leisure, business/office space, as well as retail."