Sage is the principal genus within the Lamiaceae family (Page and Olds, 2004). Sages have long been popular as summer annuals and culinary herbs in gardens around the world because of their beautiful flowers and aromatic leaves. In recent years, many species have become popular as perennials and woody subshrubs for landscape beds and water-wise gardens. To serve this increasing interest, breeders have offered new cultivars and hybrids of many sage species. Most sages prefer full sun and well-drained, light soil (Page and Olds, 2004). Many species from Mexico and South America are considered subshrubs (woody perennial base with annual herbaceous shoots) that may not be cold hardy in southeastern United States (Armitage, 2006). In a 2008–10 field trial, researchers found that autumn sage (Salvia greggii) produced an abundance of flowers throughout the summer, but some cultivars had a high mortality rate, likely due to cold, wet winter soils (B.A. Fair, unpublished data). In addition, autumn sage was highly prone to breakage during transport, transplanting, and when employing typical maintenance, such as deadheading. Other popular salvia used in those trials, including woodland sage (Salvia nemorosa) and ‘May Night’ meadow sage [Salvia ×sylvestris (Salvia pratensis × S. nemorosa)], did not flower as well or as continuously as autumn sage cultivars, but had lower mortality rates and stronger stems.
Many new introductions of autumn sage are hybrids, including ‘Hot Lips’, introduced by Strybing Arboretum in 2002 (Sayler, 2008). This popular cultivar displays white flowers with red lower lobes resembling lips, thus the common name. Plants flower in early spring through late fall and are quite drought tolerant, and attract bees and butterflies. Hybrid sage was selected for this study based on its popularity in southern gardens and to determine if a plant growth regulator (PGR) could help control stem height, potentially increasing ease of shipping and handling. In previous work (Latimer and Whipker, 2010), with meadow sage, researchers found a 40% increase in basal branching at 4 weeks after treatment with a foliar spray of benzyladenine (Configure®; Fine Americas, Walnut Creek, CA). Additionally, Banko and Stefani (1996) found that a foliar application of benzyladenine to mealy sage (Salvia farinacea) controlled height and increased branching; and when applied to meadow sage, it increased branching and delayed flowering (Carey, 2008). Most work on perennials has been conducted with such PGRs as uniconazole (Sumagic®; Valent, Walnut Creek, CA) and paclobutrazol (Bonzi®; ICI Chemicals, Millbank, England).
Much of the PGR work has focused on use of shorter-term, older chemistry with such chemicals as daminozide (B-Nine; OHP, Mainland, PA), chlormequat chloride (Cycocel, OHP), and ancymidol (A-Rest; SePRO Corp., Carmel, IN), but little work had been done with flurprimidol (Topflor, SePRO Corp.) until recently (Latimer, 2004). In addition, much of the work done has been on annuals (Holcomb and Beattie, 1990). Flurprimidol was being tested on floriculture crops but was not yet available in U.S. markets. It has a newer chemistry that makes it a highly potent gibberellin-inhibiting growth regulator (PGR) and is used commercially as a 0.38% concentrate formulation to restrict growth. Flurprimidol has been tested on a number of greenhouse plants such as dianthus [Dianthus caryophyllus (Pobudkiewicz and Nowak, 1994)], cape daisy [Osteospermum ecklonis (Olsen and Andersen, 1995)], chrysanthemum [Dendranthema ×grandiflorum (Pobudkiewicz and Nowak, 1997)], and streptocarpus [Streptocarpus hybridus (Pobudkiewicz, 2000)]. Recommendations for commercial use in greenhouse production indicate foliar spray applications of 10 to 30 mg·L−1 to potted sunflower [Helianthus annuus (Houska, 1997; Spiess-Urania, 2001)]. In European studies, recommendation for flurprimidol is to use two foliar applications at rates between 0.25 and 0.5 mg·L−1.
As perennials are gaining popularity as potted plants, as well as a landscape staple, the use of PGRs will continue to grow. Many species grow too tall too quickly during production; therefore, our objective was to determine the efficacy of various concentrations of flurprimidol substrate drenches on plant height of the perennial hybrid sage. Drenches were selected for use on the sage as foliar applications were found to be less effective despite higher rates (Krug et al., 2005; B. Whipker, personal communication).
Armitage, A.M. 2006 Armitage’s native plants for North American gardens. Timber Press, Portland, OR
Banko, T.J. & Stefani, M.A. 1996 Chemical growth control of Salvia farinacea ‘Victoria Blue’, p. 214–214. In: B.L. James (ed.). Proc. 4th Annu. Southern Nurseryman’s Assn. Res. Conf., Marietta, GA
Carey, D.J. 2008 The effects of benzyladenine on ornamental crops. North Carolina State Univ., Raleigh, MS Thesis
Dasoju, S., Evans, M.R. & Whipker, B.E. 1998 Paclobutrazol drench activity in coir- and peat- based root substrates HortTechnology 8 595 598
Holcomb, E.J. & Beattie, D.J. 1990 Growth retardants for perennials, p. 164–169. In: T.L. Davenport (ed.). Proc. 17th Annu. Plant Growth Regulat. Soc. Amer. Conf., Ithaca, NY
Houska, P. 1997 Helianthus annuus Hemmstoffe. Research report of Lehr- und Versuchsanstalt fur Gartenbau, Hannover-Ahlem, Germany
Krug, B.A., Whipker, B.E., McCall, I. & Dole, J.M. 2005 Comparison of flurprimidol to ancymidol, paclobutrazol, and uniconazole for tulip height control HortTechnology 15 370 373
Latimer, J.G. 2004 Trends and uses of plant growth regulators on herbaceous perennials, p. 1–4. In: L. Ferguson (ed.). Proc. 31st Annu. Plant Growth Regulat. Soc. Amer. Conf., Charleston, SC
Latimer, J.G., Scoggins, H.L. & Banko, T.J. 2003 Persistence of plant growth regulator effects on perennial plants in the nursery Acta Hort. 624 229 232
Latimer, J.G. & Whipker, B.E. 2010 Configure product information and university trial results. Fine Americas, Inc. Walnut Creek, CA
Page, S. & Olds, M. 2004 Botanica: The illustrated encyclopedia of over 10,000 garden plants and how to cultivate them. 3rd ed. Random House, Sydney, Australia
Pobudkiewicz, A. 2000 Controlling the growth habit of streptocarpus hybrids with flurprimidol J. Fruit Ornamentals Plant Res. 8 9 17
Pobudkiewicz, A. & Nowak, J. 1994 The influence of flurprimidol and uniconazole on growth of the CMM dwarf Dianthus caryophyllus L. cv. Snowmass J. Fruit Ornamentals Plant Res. 2 43 52
Pobudkiewicz, A. & Nowak, J. 1997 Response of chrysanthemum (Dendranthema grandiflora Kitam) cvs Altis and Surf to flurprimidol application J. Fruit Ornamentals Plant Res. 5 135 142
Sayler, R.D. 2008 WSU Arboretum and Wildlife Conservation Center. 1 Jan. 2012. <http://www.arboretum.wsu.edu/garden_blog_files/hot_lips.html>
Selmer, J.C., Adins, C.R., McCall, I. & Whipker, B.E. 2001 Pampas grass responses to ancymidol, paclobutrazol, unconizole substrate drenches HortTechnology 11 216 219
Spiess-Urania 2001 Topflor, p. 464–472. In: Spiess-Urania Chemicals GmbH. 2001 produktinformation. Spiess-Urania Chemicals, Hamburg, Germany
Whipker, B.E., McCall, I., Gibson, J.L. & Cavins, T.J. 2004 Flurprimidol foliar sprays and substrate drenches control growth of ‘Pacino’ pot sunflowers HortTechnology 14 411 414