The conferring of the Golden Rose, blessed with great solemnity on Lætare Sunday, is an ancient tradition of the Roman Pontiffs, dating back, probably, to the time of Charlemagne in the eighth century when it replaced the older custom of bestowing golden keys. The rose has been bestowed upon Catholic kings and queens, princes and princesses, and other distinguished persons, sanctuaries and churches of great import, governments, and cities. The bestowal of the rose signifies the esteem and affection of the Roman Pontiff.
The Golden Rose bestowed upon Queen Mary Adelaide of Piedmont-Sardinia by Blessed Pope Pius IX in 1847
From the Catholic Encyclopedia:
The golden flower and its shining splendour show forth Christ and His Kingly Majesty, Who is heralded by the prophet as "the flower of the field and the lily of the valleys"; its fragrance shows the sweet odour of Christ which should be widely diffused by His faithful followers (Pope Leo XIII, Acta, vol. VI, 104); and the thorns and red tint tell of His Passion according to Isaiah 63:2: "Why then is thy apparel red, and thy garments like theirs that tread in the winepress?"
The Golden Rose Bestowed Upon the National Shrine of the Immaculate Conception in Washington, D.C. by Pope Benedict XVI in 2008
The blessing of the Golden Rose (modern version):
O God! by Whose word and power all things have been created, by Whose will all things are directed, we humbly beseech Thy Majesty, Who art the joy and gladness of all the faithful, that Thou wouldst deign in Thy fatherly love to bless and sanctify this rose, most delightful in odour and appearance, which we this day carry in sign of spiritual joy, in order that the people consecrated by Thee and delivered from the yoke of Babylonian slavery through the favour of Thine only-begotten Son, Who is the glory and exultation of the people of Israel and of that Jerusalem which is our Heavenly mother, may with sincere hearts show forth their joy. Wherefore, O Lord, on this day, when the Church exults in Thy name and manifests her joy by this sign, confer upon us through her true and perfect joy and accepting her devotion of today; do Thou remit sin, strengthen faith, increase piety, protect her in Thy mercy, drive away all things adverse to her and make her ways safe and prosperous, so that Thy Church, as the fruit of good works, may unite in giving forth the perfume of the ointment of that flower sprung from the root of Jesse and which is the mystical flower of the field and lily of the valleys, and remain happy without end in eternal glory together with all the saints.