Scheduling crops to flower on specific dates requires a knowledge of the relationship between temperature and time to flower. Our objective was to quantify the effect of temperature on time to flower and plant appearance of four herbaceous perennials. Field-grown, bare-root Coreopsis grandiflora (Hogg ex Sweet.) `Sunray', Gaillardia ×grandiflora (Van Houtte) `Goblin', and Rudbeckia fulgida (Ait.) `Goldsturm', and tissue culture—propagated Leucanthemum ×superbum (Bergman ex J. Ingram) `Snowcap' plants were exposed to 5 °C for 10 weeks and then grown in greenhouse sections set at 15, 18, 21, 24, or 27 °C under 4-hour night-interruption lighting until plants reached anthesis. Days to visible bud (VB), days to anthesis (FLW), and days from VB to FLW decreased as temperature increased. The rate of progress toward FLW increased linearly with temperature, and base temperatures and degree-days of each developmental stage were calculated. For Coreopsis, Leucanthemum, and Rudbeckia, flower size, flower-bud number, and plant height decreased as temperature increased from 15 to 26 °C.
Mei Yuan, William H. Carlson, Royal D. Heins and Arthur C. Cameron
David C. Zlesak and Brent J. Hanson
, dwarf stature of ‘Tuscan Sun’ proved to be stable. Description Heliopsis helianthoides is a clump-forming, herbaceous perennial in the Asteraceae family and is native to the prairies of the eastern and central United States and eastern Canada
Uttara C. Samarakoon, David J. Woolley, Ed R. Morgan and Keith A. Funnell
In recent years, new gentian cultivars (particularly Gentiana triflora Pall and Gentiana scabra Bunge) have been released for production of cut flowers or potted plants. As a herbaceous perennial, gentians overwinter as a crown comprised of an
Christine E. Thuring, Robert D. Berghage and David J. Beattie
). By contrast, many herbaceous perennials perform well only when irrigation is provided, even at greater substrate depths ( Dunnett and Nolan, 2004 ; Durhman et al., 2007 ; Monterusso et al., 2005 ; Rowe et al., 2006 ). While 80 to 100 mm of
Neil Anderson, Peter Ascher, Esther Gesick, Lee Klossner, Neal Eash, Vincent Fritz, James Hebel, Stephen Poppe, Judith Reith-Rozelle, Roger Wagner, Susan Jacobson, David Wildung and Patricia Johnson
). Garden chrysanthemums are the number one herbaceous perennial in the United States, with a wholesale farmgate value of $141.845 million in 2005 ( U.S. Dept. Agr, 2006 ). Numerous factors contribute to the long-term popularity of garden chrysanthemums
L.P. Perry, S. Adam and M.R. Huh
Catherine M. Whitman, Royal D. Heins, Arthur C. Cameron and William H. Carlson
The influence of cold treatments and photoperiod on flowering of 8- to 11-node and 18- to 23-node Lavandula angustifolia Mill. `Munstead' plants from 128-cell (10-mL cell volume; P1) and 50-cell (85-mL cell volume; P2) trays, respectively, was determined. Plants were stored at 5 °C for 0, 5, 10, or 15 weeks, then forced under a 9-h photoperiod (SD), or under a 4-h night-interruption (NI) (2200 to 0200 hr) photoperiod at 20 °C. Percentage of plants flowering, time to flower, and plant appearance were evaluated. Increasing duration of cold treatment was associated with an increase in flowering percentage in plants from both cell sizes. More plants flowered under NI than SD except in P2 cooled for 15 weeks, where all plants flowered. Average time to visible bud (VB) and to opening of the first flower (FLW) generally decreased with increasing duration of cold treatment. Inflorescence count in P2 plants increased with increasing duration of cold treatment. To determine the relationship between forcing temperature and time to flower in L. angustifolia `Munstead', three sizes of plants were exposed to 5 °C for 13 weeks and then forced under a 4-h NI (2200 to 0200 hr) at 15, 18, 21, 24, or 27 °C. Plants generally flowered more quickly at higher temperatures, time to FLW decreasing from 77, 71, and 60 days at ≈15.6 °C to 46, 40, and 36 days at ≈26 °C for P1, P2, and 5.5-cm (190-mL pot volume) (P3) plants, respectively. Generally, P1 plants flowered 5 to 10 days later than P2, and P2 flowered 5 to 10 days later than P3.
Erik S. Runkle, Royal D. Heins, Arthur C. Cameron and William H. Carlson
Phlox paniculata Lyon ex Pursh `Eva Cullum' plants were grown under seven photoperiods following 0 or 15 weeks of 5 °C to determine the effects of photoperiod and cold treatment on flowering. Photoperiods were a 9-hour day extended with incandescent lamps to 10, 12, 13, 14, 16, or 24 hours; an additional treatment was a 9-hour day with a 4-hour night interruption (NI). Noncooled plants remained vegetative under photoperiods ≤13 hours; as the photoperiod increased from 14 to 24 hours, flowering percentage increased from 20 to 89. Flowering of noncooled plants took 73 to 93 days. Flowering percentage was 19, 50, or 100 when cooled plants were held under photoperiods of 10, 12, or ≥13 hours or NI, respectively. Time to flower in cooled plants progressively decreased from 114 to 64 days as the photoperiod increased from 10 to 24 hours. Reproductive cooled plants had at least three times more flowers, were at least 50% taller, were more vigorous, and developed seven or eight more nodes than did noncooled plants. Photoperiod had no effect on height of flowering plants.