Simply stated, senescence is what happens to all living things as they age and progress towards death. An uncut flower undergoes senescence as it matures. The hormone ethylene, naturally produced by plants, kick starts the process of senescence. Petals and leaves begin to lose their color, wilt, wither and eventually drop. Therefore, staving off senescence in a cut flower for as long as possible lengthens the flower's life span and the charm of the bloom. Project director, M. Jones, of Ohio State University's Horticulture and Crop Science not only studied flower senescence, but also the use of genetic engineering to "create petunias with extended flower longevity."
Typical Life Span
The Gardener's Paradise website lists cut flowers with life spans of about one week that include dahlias, Gerber daisies, irises and delphiniums. Cut flowers that last for about 10 days include gladioli, statice, lisianthus, sunflowers and liatris. Astilbe, baby's breath, carnations, strawflowers, chrysanthemums and properly treated roses and lilies are all long-lasting cut-flower varieties that have life spans of more than 10 days.
Proper Water Temperature
A critical step in assuring that cut flowers attain the longest life span possible is to provide them with the proper water temperature. Angle-cut flower stems need immersing in clean containers of fresh, clear, room-temperature water for several hours. Adequately hydrated cut flowers also benefit from refrigeration -- slightly above freezing -- for about six hours before display in a vase or bouquet, according to Suzy Bales' "New York Times" 2003 review of the book, ''Specialty Cut Flowers," published by Timber Press in the same year.
Development and Harvesting Time
The temptation to harvest flowers that are in full, vibrant bloom may be overwhelming, but most cut flower have longer life spans if they are snipped while buds are just beginning to open or are only partially open. The Perishable News website states that the leaves, stems and blooms should be free from moisture if packed for shipping.
Steps to Reduce Ethylene
Certain anti-ethylene compounds in the form of sprays or sachets prevent cut flowers from hastening into senescence. Adding products that contain silver-thiosulfate to cut flower stems immersed in water greatly add to a flower's longevity and suppress the hormone ethylene's destructive effects.