Whenever the public necessity, convenience, general welfare or good zoning practice require, Council may by ordinance, after recommendation thereon by the Planning Commission and subject to the procedure provided in this section, amend, supplement or change the regulations, district boundaries or classifications of property, now or hereafter established by this Zoning Ordinance or amendments thereto. It shall be the duty of the Planning Commission to submit its supplements. An amendment, supplement, reclassification or change may be initiated by the Commission on its own motion or by a verified application of one or more of the owners or leasees of property within the area proposed to be changed or affected by this Zoning Ordinance.