Yes, please. My Church has flowers on the altar during all major holiday seasons
From the General Instruction of the Roman Missal No. 305 “-Floral decorations should always be done with moderation and placed around the altar rather than on its mensa.” http://www.vatican.va/roman_curia/congregations/ccdds/documents/rc_con_ccdds_doc_20030317_ordinamento-messale_en.html#II._ARRANGEMENT_OF_THE_SANCTUARY__FOR_THE_SACRED_SYNAXIS__(EUCHARISTIC_ASSEMBLY)