Back to top

Cut Flower Physiology

Chris Wien

Note: Chris Wien, who pioneered this cut flower physiology and high tunnel research, retired in September 2015. If you have questions about on-going research along these lines, contact Neil Mattson.

In recent years, I have become interested in ornamental plants used as cut flower species.  The main focus is on production techniques, but the physiological bases that govern plant performance is also a strong interest.   

The technique that has a lot of advantages for cut flower production is the use of high tunnels, simple unheated greenhouses in which plants are grown in the ground.  These structures protect from frost, and thus allow plants to be grown earlier in spring and later in fall.  They protect against wind, and reduce the loss of flower quality by shielding from rain.  See Cornell high tunnel website for more information.

When plants are grown out of season, they are exposed to daylengths that are not usual, and certain crops show abnormal flowering because of that shift.  Two of these crops are sunflowers, and Rudbeckia hirta  (Blackeyed Susan).


  • Sensitive to daylength in the first 3 weeks after emergence.
  • Many varieties are short-day plants.
  • Relatively fewer are day-neutral.
  • Short-day types flower 3 weeks earlier when grown in 12-hour days than if grown in our summer (15 hrs).
  • Early flowering lines have small flowers, short stalks.

Table summary:  Daylength response of sunflowers

Blackeyed Susan:

  • Sensitive to daylength throughout its life.
  • All varieties tested are long-day plants.
  • In mid-summer, when days are long, plants have tall stalks and showy flowers.
  • In fall, flower stalks are short, and plants stop flowering as days get shorter. We are testing solar-operated landscape lights to trick the plants into flowering in fall.

Other fun projects ask the questions:

  • Can we increase flower stem length with shading treatments?
  • Will removing the growing point in the seedling stage increase the number of flower stems in several flower species?
  • What happens when flower seedlings are left in a seedbox too long?
  • Which new varieties of the many cut flower species are most productive and attractive, and last long in the vase?

Cut flower research summaries

Here are summaries of my recent cut flower research: