182 There are, besides, other exercises of piety which, although not strictly belonging to the sacred liturgy, are, nevertheless, of special import and dignity, and may be considered in a certain way to be an addition to the liturgical cult; they have been approved and praised over and over again by the Apostolic See and by the bishops. Among these are the prayers usually said during the month of May in honor of the Blessed Virgin Mother of God, or during the month of June to the most Sacred Heart of Jesus: also novenas and triduums, stations of the cross and other similar practices.
Source: Mediator Dei (Vatican.va)