Cut sunflowers are desirable and available nearly year-round (Nau, 2011) but are especially popular in the fall and summer months (Wien, 2009b; Yañez et al., 2012). Sunflowers are quite popular as fresh cut flowers year-round, largely due to the array of colors and growth habits now available (Dole and Wilkins, 1999; Nau, 2011). They are also easy to grow from seeds and have a relatively short cropping time, 60 to 70 d, depending on the cultivar (Armitage and Laushman, 2008). These characteristics make sunflowers an ideal niche, locally grown crop for greenhouse crop producers who, particularly in Wyoming, may be a state away from a cut flower wholesaler.
The potential for year-round production of cut sunflowers has been investigated in other states and countries such as Hawaii (Criley, 2007), New York (Wien, 2006, 2007, 2012a, 2012b), Italy (Gimelli et al., 2003), The Netherlands (Blacquière et al., 2002), and Japan (Hayata and Imaizumi, 2000; Yañez et al., 2004, 2005). Studies concerning year-round production are of interest because, although many cultivars are day neutral, photoperiod may affect flowering of some cultivars (Hayata and Imaizumi, 2000; Wien, 2006, 2007, 2012a, 2012b; Yañez et al., 2004, 2005). Although studies on year-round sunflower production have been conducted in other regions, they took place under climatic conditions quite different from those found in the Rocky Mountain west; local climate has been shown to be a major factor in cut sunflower production (Ferguson et al., 2012; Fernández-Martinez et al., 2009; Schuster, 1985). In fact, many of these studies, with the exception of those done in Hawaii and Italy, were conducted using photoperiodic lighting. Because of Wyoming’s elevation, high intensity sunlight is abundant [average elevation 6700 ft (Western Regional Climate Center, 2014)] and growing under our natural light conditions could be beneficial to growers who do not have access to supplemental and/or photoperiodic lighting or as a way to conserve energy and save on production costs.
The objective of this study was to quantify the changes in stem length and days to harvest in three sunflower cultivars grown continuously over a 14-month period of time in a greenhouse production system that can be easily integrated into the current capabilities of the majority of Wyoming greenhouses, many of which are not currently producing cut flowers and may not have access to cut flower benches or lighting capabilities.
ArmitageA.M.LaushmanJ.M.2008Specialty cut flowers: The production of annuals perennials bulbs and woody plants for fresh and dry cut flowers. Varsity Press Portland OR
BlacquièreT.StraverN.van den BergD.2002Possibilities for using photoperiodism to program flowering of sunflowers (Helianthus annuus) in the greenhouse and in the openActa Hort.580101109
DoleJ.M.WilkinsH.F.1999Floriculture: Principles and species. Prentice Hall Upper Saddle River NJ
FergusonC.G.VuppalapatiP.G.StoneM.J.GrayE.2012Evaluation of cultivars of sunflowers (Helianthus annuus L.) and selected environments for production of cut flowersJ. Kentucky Acad. Sci.739095
Fernández-MartinezJ.M.Pérez-VichB.VelascoL.2009Sunflower p. 155–232. In: J. Vollman and I. Rajcan (eds.). Oil crops. Vol. 4. Springer Sci. Business Media New York NY
NauJ.2011Helianthus p. 436–437. In: Ball red book. Vol. 2. 18th ed. Ball Publ. West Chicago IL
SchusterW.H.1985Helianthus annuus p. 98–121. In: A.H. Havley (ed.). CRC handbook of flowering. Vol. 3. CRC Press Boca Raton FL
Western Regional Climate Center2014Climate of Wyoming. 7 Aug. 2014. <http://www.wrcc.dri.edu/narratives/WYOMING.htm>
WienH.C.2009aDaylength response of sunflowers. Dept. of Hort. Cornell Univ. Ithaca NY
WienH.C.2012aCut flower cultural practice studies and variety trials 2012. Dept. of Hort. Cornell Univ. Ithaca NY
WienH.C.2012bSunflower seedling daylength response. Dept. of Hort. Cornell Univ. Ithaca NY
YañezP.ChinoneS.HirohataR.OhnoJ.OhkawaK.2012Effects of time and duration of short-day treatments under long-day conditions on flowering of a quantitative short-day sunflower (Helianthus annuus L.) ‘Sunrich Orange’Sci. Hort.140811