Evaluation of 125 Petunia Cultivars as Bedding Plants and Establishment of Class Standards

in HortTechnology

Central Florida has a climate similar to many locations in the southeastern United States and parts of Asia, Europe, and Australia. Thus, Florida is an important testing ground for new bedding plant cultivars not only in the United States, but around the world. The authors evaluated 125 petunia (Petunia ×hybrida) cultivars in replicated class tests at Bradenton, Fla. (lat. 27º4′N, long. 82º5′W) in 2000–04 and at Balm, Fla. (lat. 27º8′N, long. 82º2′W) in 2005–06. In this report they establish petunia classes and cultivar standards for each class, and provide objective plant measurements of vegetative and floral characteristics, and subjective performance ratings. Petunia cultivars were grouped into 73 classes based on the distinguishing characteristics for petunia, which are plant type and height, and flower type, color, and color pattern. Comparisons were made within each class to determine performance and to select a cultivar as the standard for the class—a plant with the highest overall performance rating that can represent the class in future trials against new cultivars. During the initial trials, larger numbers of cultivars were evaluated and eliminated from future comparisons when each class standard was selected. Many flower colors and color combinations, as well as plant types and other distinctive characteristics have been developed for bedding plants. By creating class standards for each distinctive characteristic, better choices over a wider range of classes are available to growers and landscapers in this climate. Cultivars with an outstanding overall performance rating (combined foliage, flower, arthropod feeding symptom, and disease symptom ratings ≥5.5 points on a 1 to 7-point scale) for class standard selections were (floribunda, single mix class) ‘Madness Waterfall Mix’ and [single purple (dark), red-violet class] ‘Madness Magenta’; [grandiflora, single blue (dark) class] ‘Eagle Blue’, (single orange shades/tints class) ‘Ultra Salmon’, and [single purple (dark), red-violet class] ‘Storm Violet’; and [spreading, normal, orange (dark) shades/tints class] ‘Ramblin’ Salmon Capri’, [orange (light) shades/tints class] ‘Ramblin’ Peach Glo’, [pink (dark) class] ‘Wave Pink’, [purple (dark), blue-violet class] ‘Avalanche Lavender’, [purple (light) blue-violet class] ‘Ramblin’ Lavender’, (red class) ‘Avalanche Red Improved’, (rose class) ‘Avalanche Rose Improved’, (white class) ‘Plush White’, and [spreading, tall; blue (dark) class] ‘Wave Blue’. These cultivars would likely perform well in the southern United States or areas of the world with similar heat and cold hardiness zones.

Abstract

Central Florida has a climate similar to many locations in the southeastern United States and parts of Asia, Europe, and Australia. Thus, Florida is an important testing ground for new bedding plant cultivars not only in the United States, but around the world. The authors evaluated 125 petunia (Petunia ×hybrida) cultivars in replicated class tests at Bradenton, Fla. (lat. 27º4′N, long. 82º5′W) in 2000–04 and at Balm, Fla. (lat. 27º8′N, long. 82º2′W) in 2005–06. In this report they establish petunia classes and cultivar standards for each class, and provide objective plant measurements of vegetative and floral characteristics, and subjective performance ratings. Petunia cultivars were grouped into 73 classes based on the distinguishing characteristics for petunia, which are plant type and height, and flower type, color, and color pattern. Comparisons were made within each class to determine performance and to select a cultivar as the standard for the class—a plant with the highest overall performance rating that can represent the class in future trials against new cultivars. During the initial trials, larger numbers of cultivars were evaluated and eliminated from future comparisons when each class standard was selected. Many flower colors and color combinations, as well as plant types and other distinctive characteristics have been developed for bedding plants. By creating class standards for each distinctive characteristic, better choices over a wider range of classes are available to growers and landscapers in this climate. Cultivars with an outstanding overall performance rating (combined foliage, flower, arthropod feeding symptom, and disease symptom ratings ≥5.5 points on a 1 to 7-point scale) for class standard selections were (floribunda, single mix class) ‘Madness Waterfall Mix’ and [single purple (dark), red-violet class] ‘Madness Magenta’; [grandiflora, single blue (dark) class] ‘Eagle Blue’, (single orange shades/tints class) ‘Ultra Salmon’, and [single purple (dark), red-violet class] ‘Storm Violet’; and [spreading, normal, orange (dark) shades/tints class] ‘Ramblin’ Salmon Capri’, [orange (light) shades/tints class] ‘Ramblin’ Peach Glo’, [pink (dark) class] ‘Wave Pink’, [purple (dark), blue-violet class] ‘Avalanche Lavender’, [purple (light) blue-violet class] ‘Ramblin’ Lavender’, (red class) ‘Avalanche Red Improved’, (rose class) ‘Avalanche Rose Improved’, (white class) ‘Plush White’, and [spreading, tall; blue (dark) class] ‘Wave Blue’. These cultivars would likely perform well in the southern United States or areas of the world with similar heat and cold hardiness zones.

Petunia is considered to be the first cultivated bedding plant. It is the product of complex breeding begun in the 19th century that used two South American species with white (Petunia axillaris) and purple flowers (Petunia integrifolia) (Liberty Bailey Hortorium, 1976). Subsequent petunia breeding resulted in five petunia class divisions: grandiflora, floribunda, milliflora, multiflora, and spreading. In the 1930s, the first consistently double flowers became available from Japan, whereas more flower colors were introduced in Germany from open-pollinated plants. After World War II, breeders began working on larger flowers, better growth habit, and disease and weather resistance. In the 1950s, breeders produced award-winning F1 hybrids, designated as floribundas, by crossing the larger flowered, but heat-sensitive grandifloras with the adverse weather-resistant multifloras (smaller, but more numerous flowers than grandiflora). The hybridization resulted in costly seed, but plants were superior to open-pollinated cultivars. New flower colors, such as true red and the first yellow, and plants with spreading and miniature growth habits (millifloras) expanded the available choices in color and form (Lewis, 1997; Trinklein, 2001). The range of colors, color patterns, and availability of double-flower cultivars is greatest in the grandifloras, floribundas, and multiflora classes. Use of the petunia as a model for plant physiology research resulted in important changes in plant breeding through the understanding of pollen sterility, resulting in economical production of F1 seed. These changes resulted in significant contributions to the further development of the bedding plant industry in the last half of the 20th century (Craig, 2003).

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In 2005, the wholesale value of petunias was $94 million, and ranked third in value behind pansy (Viola ×wittrockiana)/viola (V. cornuta) and impatiens (Impatiens walleriana). Florida is one of the top wholesale producers of bedding plants, and in 2005 was ranked fourth in the United States in annual bedding plant production. The wholesale value of petunia flats in Florida in 2005 was $2.0 million, whereas potted petunia sales in Florida ($4.5 million) ranked second in the United States. (U.S. Department of Agriculture, 2006).

Major seed companies from Europe, Asia, and North America produce new petunia cultivars and submit them for testing in Florida. These plants may not have been bred to survive in our climate (Nordlie, 2002). Plant breeders and seed companies use Florida trial information and apply it to similar climatic regions, such as Australia, Japan, China, and southern France (T.K. Howe, pers. comm., Dec. 2001). Therefore, evaluation of petunia cultivars in Florida is vital for continued growth of the industry.

Standards have not been fully developed for petunias that identify the great diversity of color and form found in the bedding plant industry today, nor do they recognize a cultivar as a standard for each unique class that can be used for comparison. New cultivars are often compared with a random number of cultivars, and often many of these cultivars that failed to outperform a new entry in a recent trial are used repeatedly in future trials. We estimated there are more than 360 petunia cultivars currently available in the United States from a survey of eight major companies (R.O. Kelly, unpublished data). The establishment of plant and color classes, a system of class standards for each class used for comparison with new cultivars in future trials, and the effective elimination of previously evaluated cultivars was accomplished for marigolds (Tagetes erecta and T. patula), pansies, and violas in our initial evaluations. Detailed information for each cultivar about growth, flowering, performance, and pest damage was collected in seasonal replicated trials that could be used by the scientific community as well as growers, landscapers, consumers, and seed companies (Kelly and Harbaugh, 2002, Kelly et al., 2005, 2006). This petunia study was conducted to establish classes and class standards specific to this crop (such as plant and flower forms/types, and flower colors, and color patterns) and to evaluate petunia cultivar performance.

Materials and methods

For each class, the cultivar with the highest overall performance rating was selected as the class standard. If the overall performance rating was a tie, another rating was chosen (such as the average of foliage and flower ratings, until a numerical difference was found) to determine the class standard (Kelly et al., 2005). After choosing the class standard cultivars, they were then used in subsequent trials as the “standard” for comparison of new cultivars in their class. Cultivars were placed into classes based on plant type (floribunda, grandiflora, milliflora, multiflora, and spreading), plant height, flower color, and flower color pattern, and all trial evaluations for each cultivar were grouped within that class by trial year (Table 1). In seven of the trials there were multiple cultivar comparisons within some classes; however, many cultivars evaluated were stand-alones (the sole entry for a class). If two cultivars from the same class were not evaluated in the same trial, they were reevaluated together in a future trial to determine a class standard. The number of cultivars evaluated in each trial was dependent upon economic decisions by a seed company, the development of new cultivars, and by the elimination of previously evaluated cultivars with lower overall performance ratings by the more highly rated class standards.

Table 1.

Plant and flowering characteristics and performance ratings for petunia cultivars grown in central Florida trials at Bradenton (Spring/Summer 2001–04) and Balm (Spring/Summer 2005 and 2006, and Winter/Early Spring 2005–06) and grouped within classes according to plant type and height, and flower type and color, arranged within a class by trial year.

Table 1.Table 1.Table 1.Table 1.Table 1.Table 1.Table 1.

Eight trials were conducted between Sept. 2000 and June 2006. In the initial 2000 trial, the first set of classes was established, but no class standards were selected from the 16 cultivars entered because only one cultivar per class was submitted for evaluation. In June 2001, 35 cultivars were evaluated comparing multiple cultivars per class and established the first class standard cultivars. In spring/early summer trials, 64 (2002), 17 (2003), seven (2004), five (2005), and six (2006) new cultivars were evaluated; six in Winter/Early Spring 2005–06.

Seeds were sown in seeder trays (model P-Seed20; Landmark Plastic Corp., Akron, Ohio) 21.5 × 11 × 2.4 inches on 6 and 14 Feb. 2001; 8 and 14 Feb. 2002; 11 Feb. 2003; 11, 13, and 16 Feb. 2004; 17 and 18 Feb. 2005; 19 Oct. 2005; and 1 Mar. 2006. Immediately after germination, seedlings were transplanted into Todd planter flats (model 128; Speedling, Sun City, Fla.) 1.5 × 1.5 × 2.5 inches and were grown to mature, nonflowering plugs in a greenhouse. Before transplanting into the field, flats were placed outside in full sun for 1 to 2 weeks for hardening plants. Plugs were transplanted on 20 Mar. 2001, 1 and 2 Apr. 2002, 9 and 16 Apr. 2003, 24 Mar. 2004, 6 Apr. 2005, 23 Nov. 2005, and 13 Apr. 2006 into raised ground beds 32 inches wide × 8 inches high of EauGallie fine sand (pH, 6.2–6.8). In most tests, five plants were planted along the midline at 12 to 24 inches apart, based on the space requirements of the petunia type. When space was limited in a trial, one plant was planted on the midline of the bed with four corner plants equidistantly spaced from this plant, forming a rectangle; or a sixth plant was added on the midline, equidistant from the first midline plant and two of the four corner plants, forming two chevron patterns. Cultivars within the same class were both sown and transplanted on the same date when multiple sowing or transplanting dates were indicated in the same year. Two duplicate fields were planted for each trial. One field was sprayed with pesticides on demand, whereas the other was not sprayed at all. Objective data were collected, and subjective foliage and flower quality ratings were taken from the former, whereas pest symptom ratings on plants unexposed to pesticides were taken in the latter.

Solid Nutricote 13N–5.7P–10.8K (13–13–13, 100-d slow-release type; Florikan, Sarasota, Fla.) fertilizer was applied by hand to each plant on the soil surface ≈1 inch from the plant stem under the plastic mulch in 2000–01 at 14 g/plant. Osmocote Plus 15N–3.9P–10K fertilizer slow-release type with micronutrients (15–9–12, 5–6 month; The Scotts Co., Marysville, Ohio) was used at the same rate in 2002–06. Beds were fumigated at or more than 14 d before planting with a mixture of 66% methyl bromide and 33% chloropicrin at 350 lb/acre (175 lb/acre in 2005 and 2006) and covered with white-on-black polyethylene film. Seepage irrigation water was supplied from lateral ditches spaced 40.5 ft apart, whereas in 2005–06 the seepage irrigation water was supplied from lateral ditches spaced 25 ft apart in full-sun fields or by a subsurface drip irrigation system containing one drip line, supplying water to three beds between the lateral ditches (S.A. Davis, pers. comm.) (Kelly et al., 2006; Smajstrla et al., 1992).

Integrated pest management was used in the sprayed field to determine when pesticide applications were needed to control arthropod pests and plant pathogens. Weather information was recorded by an automated weather station located at the University of Florida's Gulf Coast Research and Education Center at Bradenton [lat. 27º4′N, long. 82º5′W; American Horticultural Society (AHS) heat zone 10 (American Horticultural Society, 1999); U.S. Department of Agriculture (USDA) cold hardiness zone 9b (U.S. National Arboretum, 1990)] and Balm (near Wimauma), Fla. [lat. 27º8′N, long. 82º2′W; AHS heat zone 10 (American Horticultural Society, 1999); USDA cold hardiness zone 9a (U.S. National Arboretum, 1990)] in 2005.

In the sprayed field, plant height (from the stem base to the inflorescence tip), plant width at the widest point, and flower diameter were recorded for three plants selected from the center and edge of each plot on 30 Apr. 2001 (75–81 d from sowing), 8 to 14 Feb. 2002 (81–94 d from sowing), 6 May 2003 (84 d from sowing), 4 May 2004 (78–83 d from sowing), 23 May 2005 (94–95 d from sowing), 3 Mar. 2006 (135 d from sowing), and 14 June 2006 (106 d from sowing). In the sprayed and unsprayed fields, subjective ratings were made by the senior author two to four times between 24 Apr. and 2 June 2001, 1 May and 2 June 2002, 9 and 27 May 2003, 28 Apr. and 3 June 2004, 20 May and 20 June 2005, and 2 and 22–23 June 2006. Each time, an evaluation was made across all five or six plants in the plot, resulting in one value per plot. A scale of 1 to 7 points was used, with the highest rating being 7 points. In the sprayed field, floral characteristics were rated on the following scale: 7 points, flowers numerous, uniformly distributed overall plants, flowers were free from arthropod and disease symptoms; 4 points, average floral display, may have some pest damage but not severe enough to cause flowers to be unacceptable; and 1 point, unacceptable flower number or display, or pest damage severe resulting in unattractive flowers. Foliage ratings were made as follows: 7 points, all plants in a plot had full and uniform foliage, plants were free of arthropod and disease symptoms and abnormalities or weaknesses such as lodging; 4 points, average foliage density, minimal lodging, or some insect damage but foliage was still acceptable; 1 point, foliage sparse, stem lodging, or unacceptable pest damage making plants undesirable. In the unsprayed field, arthropod and disease ratings on flowers were made as follows: 7 points, all flowers or foliage free from arthropod feeding scars and absence of diseased tissue in the form of spots, blights, or tissue distortion incited by a pathogen; 4 points, minimal pest damage to tissue, and flowers or foliage still acceptable; 1 point, flowers severely infested and damaged, resulting in undesirable flowers or foliage. For a measure of performance over time, each foliage and flower rating in the sprayed field, and each arthropod symptom and disease symptom rating for foliage and flower in the unsprayed field taken in a season was added individually and divided by the total number of ratings in the season (two to four per trial). For a measure of overall performance, averages for the flower and foliage ratings in the sprayed field, and arthropod and disease symptom ratings for foliage and flower in the unsprayed field were added together and divided by four.

Each class was analyzed as a separate experiment. A randomized complete block experimental design was used, with three or four blocks containing five or six plants per plot. The experimental unit for objective data was the average measurement from three plants, and for subjective data was one rating value that considered all six plants in the plot. All data were analyzed by analysis of variance methods, and means of dependent variables significant at the 0.05 level of probability were separated using Duncan's multiple range test (PROC ANOVA; SAS Institute, Cary, N.C.).

Results and discussion

During the evaluation periods for the eight trials, weather conditions resulted in a minimum temperature range from 2.1 °C (21 Dec. 2000) to 10.7 °C (13 Apr. 2003), and maximum temperatures that ranged from 33.9 °C (13 June 2003) to 35.2 °C (June 2001). Total rainfall ranged from 20.6 cm (2006) to 51.1 cm (2002) (Florida Automated Weather Network, 2004).

Although many disease organisms have been isolated from petunia over time from around the world (Alfieri et al., 1994; Brunt et al., 1996; Farr et al., n.d.), petunia is considered to be relatively free of diseases causing leaf spots (Alfieri and Schubert, 1986). In Florida, petunia performs well, but ratings may decline when the weather conditions are optimum for a particular disease. In our trials, three diseases predominated if petunias were left untreated by pesticides: alternaria leaf spot or blight (Alternaria sp. on foliage) (Alfieri et al., 1994; Chase, 1998a), graymold (Botrytis cinerea) on flowers in Florida's cool winter and early spring (Chase, 1998b), and choanephora flower blight (Choanephora cucurbitarum; may cause wet rot) (Holcomb, 2003) in warm and humid weather (Daughtrey et al., 1995; University of North Carolina, n.d.).

Insect damage symptoms were primarily from thrips (Frankliniella spp.) feeding on flowers, which was difficult to control, and from lepidopterist larvae (Spodoptera spp.), which were easily controlled.

Table 1 presents the class standard for each class, with the trial year it was selected and all the cultivars evaluated with the standards; the solitary cultivar entries without comparison are also listed. Plant width, flower size, flowering earliness, cultivar quality ratings for foliage and flowers, and pest symptom ratings for arthropod and disease damage to foliage and flowers are listed in Table 1. It is important to note that cultivars can be selected as class standards and vary in performance ratings from poor to outstanding. Class standards may be visually and statistically similar to other cultivars in their class, but were chosen for future comparisons based on the largest value for overall performance. By using this class standard system, we eliminated the need to reevaluate large numbers of cultivars previously evaluated when new cultivars were released in the same class. Cultivars with an overall rating ≥5.5 points were considered outstanding, 5.0 to 5.4 points as good, 4.0 to 4.9 points as fair, and less than 4.0 points as poor.

Selecting outstanding cultivars

Ideally, class standard petunia selections would also have outstanding ratings (≥5.5 points, overall performance rating), but this was not the case in many instances. Cultivars with an outstanding overall performance rating and selected as class standard were (floribunda class) ‘Madness Waterfall Mix’ and ‘Madness Magenta’; (grandiflora class) ‘Eagle Blue’, ‘Storm Violet’, and ‘Ultra Salmon’; and (spreading class) ‘Avalanche Lavender’, ‘Avalanche Rose Improved’, ‘Avalanche Red Improved’, ‘Plush White’, ‘Ramblin’ Lavender’, ‘Ramblin’ Salmon Capri’, ‘Ramblin’ Peach Glo’, ‘Wave Blue’, and ‘Wave Pink’. Cultivars that were outstanding but not class standards, or were former class standards, were (floribunda class) ‘Madness Clear Mix’, (grandiflora class) ‘Storm Blue’ and ‘ultraviolet’, and (spreading class) ‘Avalanche Salmon’, ‘Easy Wave Pink’, ‘Easy Wave Red’, ‘Explorer Pink’, ‘Explorer Rose Pink’, ‘Ramblin’ Shades O’ Pink’, ‘Explorer Lavender’, ‘Easy Wave Red’, ‘Avalanche Tropical Red’, ‘Ramblin’ Red’, ‘Rapide Red’, ‘Explorer Rose’, ‘Opera Deep Rose’, ‘Easy Wave Rosy Dawn’, ‘Explorer White’, and ‘Ramblin White’.

Solitary cultivar entries with an outstanding overall performance rating were (floribunda class) ‘Celebrity Chiffon Morn’, ‘Celebrity Mid Blue’, ‘Celebrity White’, ‘Double Cascade Blue’, ‘Dreams Burgundy Picotee’, ‘Dreams Rose Picotee’, ‘Dreams Sky Blue’, ‘Dreams Wild Rose Mix’, ‘Eagle White’, ‘Limbo Blue’, ‘Storm Lavender’, and ‘Ultra Pastel Pink’; (milliflora class) ‘Fantasy Light Lavender’ and ‘Fantasy Mix’; (multiflora class) ‘Hurrah Pink Chiffon’, ‘Primetime Violet Star’, ‘Symphony Blue’, ‘Symphony Light Blue’, ‘Symphony Pink’, ‘Symphony Violet’, ‘Symphony Red Picotee’, ‘Symphony Rose’, ‘Symphony Rose Star’, ‘Symphony Salmon’, and ‘Symphony White’; and (spreading class) ‘Avalanche Lilac’, ‘Avalanche Pink’, ‘Easy Wave Shell Pink’, ‘Explorer Blue’, ‘Explorer Purple’, ‘Kahuna Violet’, ‘Kahuna White’, ‘Opera Light Purple’, ‘Ramblin’ Burgundy Chrome’, ‘Ramblin’ Lavender’, ‘Ramblin’ Lilac Glo’, ‘Ramblin’ Violet’, ‘Tidal Wave Cherry’, ‘Tidal Wave Hot Pink’, and ‘Tidal Wave Purple’.

Literature cited

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Contributor Notes

This research was supported by the Florida Agricultural Experiment Station.We thank Joyce Jones, Nancy West, Gail Bowman, Paulette Blanton, Logan Webb, and Jenna Adams for their excellent technical support.

Corresponding author. E-mail: harbaugh@ufl.edu.

  • AlfieriS.A.JrLangdonK.R.KimbroughJ.W.El-GhollN.E.WehlburgC.1994Diseases and disorders of plants in FloridaFla. Dept. Agr. Consumer Serv. Bul.14710711

    • Search Google Scholar
    • Export Citation
  • AlfieriS.A.JrSchubertT.S.1986Cercospora leaf spot of petunia22 Jan. 2007<www.doacs.state.fl.us/pi/enpp/pathology/pathcirc/pp285.pdf>

    • Export Citation
  • American Horticultural Society1999Heat zone map22 Jan. 2007<www.ahs.org/pdfs/05_heat_map.pdf>

    • Export Citation
  • BruntA.A.CrabtreeK.DallwitzM.J.GibbsA.J.WatsonL.ZurcherE.J.1996Plant viruses online: Descriptions and lists from the VIDE (virus identification data exchange) database22 Jan. 2007<http://image.fs.uidaho.edu/vide/refs.htm>

    • Export Citation
  • ChaseA.R.1998aWestern connection, turf and ornamentals, Western Farm Service Quarterly Newsletter: Alternaria diseases of ornamentals22 Jan. 2007<www.westernfarmservice.com/newsletters/turf/alternaria.pdf>

    • Export Citation
  • ChaseA.R.1998bWestern connection, turf and ornamentals, Western Farm Service Quarterly Newsletter: Botrytis blight on ornamentals, diagnosis and control22 Jan. 2007<www.westernfarmservice.com/newsletters/turf/botrytis.pdf>

    • Export Citation
  • CraigR.2003Creating a more beautiful world: A century of progress in the breeding of floral and nursery plantsHortTechnology30928936

  • DaughtreyM.L.WickR.L.PetersonJ.L.1995Compendium of flowering potted plant diseasesAmer. Phytopathol. SocSt. Paul, Minn

    • Export Citation
  • FarrD.F.RossmanA.Y.PalmM.E.McCrayE.B.n.dFungal databases, Systematic Botany & Mycology Laboratory, ARS, USDA23 Jan. 2007<http://nt.ars-grin.gov/fungaldatabases/fungushost/fungushost.cfm>

    • Export Citation
  • Florida Automated Weather Network2004FAWN: Report generator22 Jan. 2007<http://fawn.ifas.ufl.edu/scripts/reportrequest.asp>

    • Export Citation
  • HolcombG.E.2003First report of petunia blight caused by Choanephora cucurbitarum in the United States23 Jan. 2007<www.apsnet.org/pd/searchnotes/2003/0328-01n.asp>

    • Export Citation
  • KellyR.O.HarbaughB.K.2002Evaluation of marigold cultivars as bedding plants in central FloridaHortTechnology12477484

  • KellyR.O.DengZ.HarbaughB.K.2005Evaluation of pansy cultivars as bedding plants to select the best-of-classHortTechnology15706715

  • KellyR.O.DengZ.HarbaughB.K.2006Evaluation of viola cultivars as bedding plants and establishment of the best-of-classHortTechnology16167171

    • Search Google Scholar
    • Export Citation
  • LewisE.1997The National Garden Bureau gardening fact sheets: Petunia22 Jan. 2007<www.ngb.org/gardening/fact_sheets/fact_details.cfm?factID=4>

    • Export Citation
  • Liberty Bailey Hortorium1976Hortus third: A concise dictionary of plants cultivated in the United States and CanadaMacmillanNew York

  • NordlieT.2002University of Florida news: Experts put flowering plants “on trial” to aid consumers22 Jan. 2007<http://news.ufl.edu/2002/02/12/flowertrial>

    • Export Citation
  • SmajstrlaA.G.ClarkG.A.HamanD.Z.1992University of Florida, IFAS, EDIS: Florida irrigation systems22 Jan. 2007<http://edis.ifas.ufl.edu/AE385>

    • Export Citation
  • TrinkleinD.2001Missouri environment and garden newsletter: Petunia22 Jan. 2007<http://agebb.missouri.edu/hort/meg/archives/v7n6/meg1.htm>

    • Export Citation
  • University of North Carolinan.dDiagnosing postharvest diseases of cantaloupe: Choanephora22 Jan. 2007<www.ncsu.edu/project/cucurbitkeys/key/Diagnosing%20Postharvest%20Diseases%20of%20Cantaloupe/Media/Html/Choanephora_rot.htm>

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  • U.S. Department of Agriculture2006Floricultural crops 2006 summaryU.S. Dept. Agr., Natl. Agr. Stat. ServWashington, D.C

  • U.S. National Arboretum1990USDA plant hardiness zone map22 Jan. 2007<www.usna.usda.gov/Hardzone/ushzmap.html>

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