Whenever such a strip of land shall have been set aside by the county commission, and the said road, including said strip of land graded to the established grade, the said county commission shall have the power to have footpaths constructed and cause shade trees of uniform variety and size to be planted thereon, under the supervision of the county highway engineer; after which it shall be the duty of the road overseer of the district containing such road or roads to care for and protect the same out of the road funds of such district; provided, the said county commission may in its discretion, before appropriating any money for the construction of such footpaths, or the purchase and planting of the trees aforesaid, require the property owners owning the property adjoining said road to deposit such part of the total cost of the same with the county treasurer as the commission may deem just and proper.