More then 400 species belong to the ranunculus family. Comprised of biennials, perennials and annuals, all varieties produce ideal cut flowers. Blossoms appear in shades of pink, red, yellow and white. The perennial ranunculus varieties range in size from 6 to 18 inches in height. The plants grow from bulbs, rhizomes and tubers depending on the variety. Perennial ranunculus plants grow best in U.S. Department of Agriculture zones 8 to 11.
The flowers of the perennial ranunculus measure up to 5 inches in width. Long stems that measure 16 inches make the flower ideal as a cut flower. One perennial ranunculus bulb can produce up to 25 flower-heads in a season. Flowers appear from May to September. The flowers track the sun as it moves across the sky.
The ranunculus perennials withstands temperatures down to 20 degrees Fahrenheit for short periods. The plant requires temperatures between 45 to 50 degrees F at night for abundant growth. A cool season plant, the ranunculus does not withstand high temperatures well and will easily wilt. The plant prefers a daytime temperature of 60 degrees F. A few perennial varieties, such as Ranunculus cooleyae, withstand cold winters well and blossoms appear as soon as the snow melts, according to the Washington Department of Natural Resources.
All parts of the ranunculus are poisonous. Often called "the blister plant" because blisters arise on the mouth of anyone that consumes the plant. A few individuals often suffer from contact dermatitis when their skin comes into contact with the plant's sap. If large quantities of the plant are consumed, death can result, according to North Carolina University Cooperative Extension Service. The plant is especially toxic to livestock, as they will graze large amounts.
Seed production follows flowering. Tiny seed pods appear that contain numerous 1/8-inch seeds. Seeds are easily dispersed by the wind, so the plant quickly escapes cultivation to grow in numerous locations.
The perennial ranunculus flowers last up to seven days when cut and placed in water. The flowers live longer if cut in the morning, when they still retain moisture. Ranunculus buds planted shortly after they begin to flower will finish flowering in the vase.