Circular 328
Alabama Agricultural Experiment Station
Mike Weiss,
Interim Director
Auburn University
Auburn, Alabama
November 2004
| J. Raymond Kessler, Jr., Jon Coleman, and Arnold Caylor |
TABLE OF CONTENTS
Table 1, Performance Ratings by species
ACKNOWLEDGMENTS
The authors gratefully acknowledge the substantial donations of potting mix from Fafaard, Inc. and seeds from Ball, Benary, Goldsmith, Grimes, Pan American, Sakata, and Sygenta Seed Companies and transplants from Proven Winners as well as the time and efforts of Jon Coleman at Auburn and Arnold Caylor and his crew at the North Alabama Horticultural Substation in Cullman, Alabama.
INTRODUCTION
Bedding plant growers frequently choose cultivars based on pack performance and adaptability to their production conditions. Garden performance of these selected cultivars within the marketing region is also an important factor in customer satisfaction and repeat sales. However, information on garden performance of bedding plant cultivars for Alabama may be difficult to obtain. Further, growing conditions vary widely from north to south within the state.
Therefore, in the summer of 2004, 127 bedding plant cultivars were evaluated on the Auburn University campus in Auburn, Alabama, and 43 bedding plant cultivars were evaluated on the North Alabama Horticultural Substation in Cullman, Alabama. The objective of this study was to determine overall garden performance of summer-flowering annual plant cultivars (bedding plants) at a northerly and southerly location in the state. Results generated from this study will assist Alabama horticultural professionals and consumers in bedding plant selection. However, landscape performance may vary from year to year as climatic conditions affect performance.
METHODS
Seeds and plants for the trial entries were donated by horticultural companies. Seeds were germinated in 288 plug flats and transplanted into 606 market flats at the Auburn University, Department of Horticulture, Paterson Greenhouse Facility. Rooted liners were planted into 4-inch pots. Fafard 3B potting mix was used in all containers.
Raised beds were prepared by tilling at both locations and the soil was amended and mulched with 3 inches of “amendment grade” (fine) aged pine bark.
| All beds were located in full sun. A commercially available fertilizer and dolomitic limestone were pre-plant incorporated into the beds based on soil test recommendations. No additional fertilizer was applied during the season at Auburn, but several applications of liquid fertilizer were applied at Cullman. A preemergent herbicide, Pendulum 2G, was applied at 2.3 pounds per 1,000 square feet. Rainfall was supplemented using overhead sprinkler irrigation at Auburn and drip irrigation at Cullman to provide an equivalent of 1 inch of water per week. No deadheading of spent flowers or other maintenance was performed on any of the plants with the exception of hand weeding and Roundup herbicide applications between the beds. No pesticides were applied during the trial. Transplants were planted in early June at Auburn and in mid June at Cullman. |
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Each of the replications for each plant entry were evaluated every two weeks from June 30 to September 15 at Auburn and June 17 to September 9 at Cullman. Plants were rated by the same individual at each locations using a 1 to 5 scale. Flowering plants were rated primarily on their floral displays, while size, shape, and freedom from insect or disease blemishes were also considered. A rating of 1 indicated a small display of foliage with no flowers present; 2--adequate amount of foliage with one or two flowers present; 3--sufficient foliage and floral display to be attractive in the landscape; 4--above average floral display and sufficient foliage display; and 5--superior floral display and sufficient foliage display. A rating of 0 indicated the plant had died. Ratings were made in whole number units. Any plant with an average rating of 2.5 or higher could be considered acceptable in the landscape and would be a worthwhile addition to a garden located in USDA Hardiness Zones 7 or 8.
RESULTS
Average performance rating for all bedding plant species tested at Auburn and Cullman is in Table 1. In Auburn, the best performing bedding plant species in the “a” category was Alternanthera, Eragrostis, and Euphorbia while Melinis and Gomphrena were in the “b” category. Plectranthus, sage, Penstemon, and basil were best performers in the “c” category. The “d” category was occupied by many well-known bedding plants including Ageratum, annual vinca, Profusion Zinnia, marigold, and Verbena. The “e” category completes all those species with an average rating of 2.5 or above and included Angelonia, Cosmos, Portulaca, Pentas, Torenia, and Gaillardia. At Cullman, Alternanthera, Gomphrena,and Plectranthus were in the “a” category, and basil, Salvia, and Euphorbia were in the “b” category, all of which rated highly at Auburn except Salvia. Profusion Zinnia, Pentas, annual vinca, sage, Petunia, and Angelonia were in the “c” category, all of which rated highly at Auburn except Petunia. Gaillardia, Celosia, Scaveola, geranium, and Phloxwere in the “d” category, all with average ratings of 2.5 and above except Phlox. Seventy percent of species rated 2.5 or higher at Cullman while only 43 percent rated 2.5 or higher at Auburn. These percentages were similar in 2003.
Average performance rating for bedding plant species tested while useful, does not provide a complete picture of performance through the season. The charts in this document depict the average performance rating of bedding plant species for the two locations at each evaluation date. At Auburn, many bedding plant species increased in performance rating up to about the middle of August and then declined. These species could be effectively used in the landscape for the first part of the summer but would need to be replaced in late summer or early fall. In contrast, other species increased in performance rating and maintained good performance until the end of the trial. These included Alternanthera, Ageratum, Begonia, Eragrostis, Euphorbia, Melinis, and sage. A few species at Auburn did not show good performance for the duration of the trial, particularly Arabis, Callibrachoa, Coreopsis, and Oenothera. The patterns of performance over time observed at Auburn were not the same at Cullman. Species that performed well at Cullman generally maintained increasing performance ratings for the duration of the trial while those that performed less well only showed slow declines such as Arabis. This, along with the data from Table1, illustrates the differences in performance between the two locations and that many classic bedding plants may not be as well suited to the southern parts of the state.
The average performance rating for all bedding plant cultivars tested at Auburn and Cullman is in Table2. The best performing entry at Auburn was Alternanthera ‘Gail's Choice’ with an average performance rating of 4.7. Eragrostis ‘Wind Dancer’ came in second with a rating of 4.5 while Euphorbia ‘Diamond Frost’ came in third with a rating of 4.4. In fourth place was Melinis ‘Savannah’ with ratings of 4.2, and Gomphrena ‘Purple Gomp’ took fifth place with a rating of 4.2. Sixth place belonged to Begonia ‘Baby Wing Pink’, Verbena ‘Garden Leader Lavender’, and annual vinca ‘Titan Lilac’ with ratings of 3.6 while Plectranthus ‘Silver Shield’ took sixth place with a rating of 3.4. Seventh place was crowded by Penstemon ‘Purple Majesty’, sage ‘Scarborough’, Torenia ‘Catalina Blue’, and annual vinca ‘1st Kiss Icy Pink’, ‘Pacifica Halo Orchid’, and ‘Titan Blush’ with ratings of 3.3. Basil ‘Garden Leader Rascal’, Scaveola ‘Whirlwind Blue Velvet’, and annual vinca ‘1st Kiss Coral’, ‘1st Kiss Blush’, and ‘Pacifica Magenta’ shared eighth place with ratings of 3.2. Ageratum ‘Artist Alto Blue’, marigold ‘Durango Mix Outback’, Petunia ‘Supertunia Silver’, Verbena ‘Quartz Silver’, and annual vinca ‘1st Kiss Blueberry’, ‘1st Kiss Peach’, and ‘Titan Burgundy’ shared ninth place with ratings of 3.1 while Ageratum ‘Artist Blue Violet’ and annual vinca ‘1st Kiss Sunrise’, ‘1st Kiss Ruby’, and ‘Sunsplash Red’ shared tenth place with ratings of 3.0.
The best performing entries at Cullman were Alternanthera ‘Gail's Choice’, Plectranthus ‘Silver Shield’, and Gomphrena ‘Purple Gomp’ with performance ratings of 4.0. Basil ‘Garden Leader Rascal’ took second place with a rating of 3.7 and third place belonged to Euphorbia ‘Diamond Frost’ and Salvia ‘Sizzler Mix’ with ratings of 3.5. Petunia ‘Ramblin Lilac Glo’ and annual vinca ‘Pacific White’ and ‘Titan Lilac’ took fourth place with ratings of 3.4 while fifth place was held by Zinnia ‘Profusion Orange’, ‘Profusion Fire’, and ‘Profusion White’ with ratings of 3.3. Petunia ‘Ramblin Nu Blue’ and ‘Storm Blue’ and Zinnia ‘Profusion Apricot’ and ‘Profusion Cherry’ captured sixth place with a rating of 3.2. Alone in seventh place was Pentas ‘Graffiti White’ with a rating of 3.1, but eighth place was mixed with Penstemon ‘Lilliput Pink’, Petunia ‘Supertunia Silver’, and annual vinca ‘Rasberry Red Cooler’ with ratings of 3.0. Ninth place was shared by Angelonia ‘Angelface Blue’ and ‘Angelface White’, basil ‘Scarborough’, and annual vinca ‘Grape Cooler’ with ratings of 2.9. In tenth place was Angelonia ‘Angelface Blue Bicolor’ and Celosia ‘Fresh Look Yellow’ with ratings of 2.8.
EVALUATOR'S NOTES
Without question, the real show stoppers at Auburn were an unusual mix of plants that most consumers may not be familiar with. Alternanthera ‘Gail’s Choice’ (Calico Plant) is a great foliage plant, and ‘Purple Knight’ was the best performer in the 2003 trial. Give Alternanthera plenty of room because it is a large plant at about 3 feet by 3 feet. Other unusual high performers were Eragrostis ‘Wind Dancer’ (Blue Love Grass), Euphorbia ‘Diamond Frost’, Melinis ‘Savannah’ (Savannah Ruby Grass), and Plectranthus ‘Silver Shield’. Melinis is a new ornamental grass with beautiful pink flower heads, and Eragrostis has steel-blue foliage. It is no surprise that Gomphrena ‘Purple Gomp’ performed well because this species has a track record of good performance in the southeast United States. Plectranthus is a large plant grown mainly for its soft silvery-gray foliage, and sage and basil are well known as heat-tolerant herbs. Zinnias in the Profusion series were placed in a separate group this year, and as a group performed better than the Zinnia elegans cultivars. The high average rating for the Torenias grown in full sun was somewhat a surprise because this plant is often reported to require some shade. We can always depend on the annual vincas and Begonias to put on dependable show. Unlike past years, many of the same plants that performed well at Auburn also performed well at Cullman. However, more Petunia and Profusion Zinnia cultivars were in the top ten at Cullman than at Auburn.