On or before March 1 of each year, the Superintendent of Streets shall make an assessment of the cost and expenses incurred in the planting, care and maintenance of the grass, shrubbery and trees in any street ordered under the authority of this chapter, during the year ending on the preceding December 31. The assessment shall refer to the street upon which such planting, care and maintenance has been assumed, the work done and shall show the entire amount of the costs and expenses incurred by the City pertaining to each lot for the cost and expense of planting, caring and maintaining the grass, shrubbery and trees in front of each lot and upon the same side of the street, during such period. Such assessment shall also show the name of the owner of each such lot if known and when the name of the owner is unknown, the assessment may be made to unknown owners and to the number of each lot, which shall correspond with the number of the same on the diagram. The diagram referred to in section 34-6 shall be attached to the assessment. (Code 1962, § 35-30)