I used to work in a psych hospital. When visitors brought flowers we displayed them behind a glass window in the nursing station so patients could at least see them. The flowers were not allowed in rooms because the glass vases could be used as weapons. The flower water might be ingested to try to kill oneself. The flowers and leaves might be ingested to try to kill oneself. If the flowers had thorns or stiff stems these might be used to cut oneself or other patients. We did have big windows in each room that looked out on natural areas. Each day, patients got 2-3 times outside supervised in the fenced natural areas. They could go barefoot in the grass if they wanted. It wasn't much, but I think the fresh air helped mood. If visitors wanted to bring gifts, we would encourage books, cards, letters, or stuffed animals (without ribbons around their necks).