Ranunculus flowers look almost too perfect to be real. Their rose-like blossoms have tissue-thin petals and they come in colors that range from cream and pale yellow to apricot, pink, orange, red and burgundy. Ranunculus are cool season flowers that grow best in spring-like temperatures of about 55°F. As cut flowers, ranunculus have a wonderfully long vase life. They open in the day and close at night. Harvest the flowers after they have opened and closed a few times. Three days of opening and closing is ideal. If the center bud feels hard, wait and check it the next day. It should feel squishy like a marshmallow. Flowers that are harvested at this stage should have a vase life of 10 days.