No person, firm, partnership, corporation, limited liability company, or other entity shall do or cause to be done any grading, stripping, cutting, or filling upon any real property situated within the corporate limits of the city unless and until a grading permit has been obtained which has been issued by the Building Inspector and approved by the City Engineer and the Director of Public Works. No grading permit shall be required for the tilling or cultivation of any real property within the city for the purpose of growing flowers, vegetables, or other plants or for any minor alteration or changes in the landscaping and gardening of said real property.