Agricultural Research Technician
Department of Horticultural Science
JC Raulston Arboretum
General Introductory Notes and Acknowledgements
Understanding Our Data
Plant Material Sources
Best of Breed
Leaders of the Pack
Early Season Leaders of the Pack
Late Season Leaders of the Pack
Cultivar Series Summaries
The Trial Gardens for seasonal color plant materials are located at NC State University within the JC Raulston Arboretum (JCRA) in Raleigh. The JCRA is an eight acre site administered by the Department of Horticultural Science and located on 35° 47'N latitude, longitude 78° 42' W, with an elevation of 400 feet.
Plants to be entered into our trials are received in a variety of ways. About half are germinated from seeds while the remainder originate as rooted cuttings or established cell plugs. Virtually all are grown within controlled greenhouse environments prior to placement in protected outdoor structures for hardening off. They were planted into their permanent trial bed locations on October 30, 2007. The predominant plant spacing in the trials was 18 inches × 12 inches (in-row × between-row spacing). Seven plants of each entry were used to evaluate landscape performance and ratings were taken weekly.
We thank the following companies for their support of material donations:
• Coor Farm Supply, P.O. Box 525, Smithfield,
• Dillen Products, P.O. Box 738, Middlefield, OH 44062
• Fafard, Inc., P.O. Box 26, Anderson, SC 29622
• The Scotts Co., 14111 Scottslawn Road, Marysville, OH 43041
We are especially thankful to the departmental staff and the volunteers of the JC Raulston Arboretum who assisted in transplanting the annual beds. We couldn't have done it without you all!
This is recorded as the total number of weeks in flower throughout the entire season. It should give you an idea of whether or not a plant is best used for the whole season or as a "fill-in" for special displays. Obviously, those species grown for foliage interest alone, e.g. Acalypha, may score poorly in this column and should not be rejected based on this value alone!
Plants were given a visual rating weekly by the same person beginning November 20, 2007, (about three weeks after planting) through April 8, 2008. The overall rating was based on plant performance and appearance, including floriferousness, plant size and shape, and freedom from insect and disease problems. The rating scale ranged from 1 (very poor) to 5 (excellent) with 0.5 unit increments possible; a 0 rating indicated that all plants of the cultivar trial died.
The first statistic that readers run to is likely the "all season average." This value represents overall performance for the entire season. However, realizing that there are many species/cultivars which may do better in one part of the growing season versus another, we also provide an "early season average" and "late season average" for each entry. The former is the average of the first 8 weeks of the evaluation period and the latter represents the end of the season. This information may be useful in planning short term plantings with high impact as well as for studying temperature preferences, life cycle changes, and/or the impact of photoperiod on plant performance. The "number of weeks rated above 3" gives you an idea of how consistently throughout the season an entry is an exemplary performer.
• "The Top 10" - this list shows the species/cultivars with the top ten "All Season Averages." These were our best overall performers. When the list exceeds ten, there were ties.
• "Leaders of the Pack" – lists all species/cultivars with an "All Season Average" of 3.0 or better. We consider this the arbitrary cutoff rating for a "significant performer" in Raleigh. This list shows all your best choices for planting, listed by plant name.
• "Leaders of the Pack – Early Season" – this shows entries with "Early Season Averages" of 3.0 or better based on the first eight weeks of evaluation. This group may prefer warmer temperatures or only have a relatively short ornamental life, and might not show up on the "Leaders of the Pack" list above.
• "Leaders of the Pack – Late Season" – this shows entries with "Late Season Averages" of 3.0 or better based on the end of the season evaluations. They may prefer warm temperatures or flower as daylengths start to lengthen, again sometimes precluding them from inclusion on the overall "Leaders of the Pack" list.
• "Best of Breed" - shows the best performing cultivars in each species.
• "Summary by Series" - groups the information for cultivar series where appropriate. This can be a quick reference for related cultivars as well as a handy tool to judge the general performance of an entire series offered by a breeder/company.
Visit our Web site and Help Yourself!
Once at our Web site, be sure to subscribe to the Cuttings from the JC Raulston Arboretum to receive free, periodic updates from the JC Raulston Arboretum via e-mail, complete with digital images!
Sometimes I think that the one number most often overlooked in our report is the variance. Go to the "Leaders of the Pack" data tables and look for its column. The term itself may be intimidating in light of its mystery, but need not be as it can be most informative. Simply put, the lower the variance, the most alike all plants are in the group evaluated, and hence the greater the uniformity. For so many in the commercial landscaping sector, they live and die by uniformity because appearance can be everything. So, by using a selected variance value of 0.1 as our very tough cut-off, we can really see which plants are setting the standard for superb uniformity.
Whereas small variance values indicate excellent uniformity, the opposite can point out cultivars with a "mind of their own!" They are not necessarily a poor choice, just not ruler perfect. In this case, plants with variance values of 1.0 or more were highlighted for great differences observed during the season.
Please get in touch with these companies if you have specific questions regarding individual species and cultivars.
Ball Seed Co., P.O. Box 335, West Chicago, IL 60185
Ernst Benary of America, Inc., 1444 Larson Street, Sycamore, IL 60178-9705
Campbell Road Nursery, 2804 Campbell Road, Raleigh, NC 27606
Goldsmith Seed, Inc., 2280 Hecker Pass Highway, Gilroy, CA
Hem Genetics, 4949 Cornell Road, Okemos, MI 48864
PanAmerican Seed Co., P.O. Box 438, West Chicago, IL 60185
Proven Winners, 1021 River Ridge Lane, Saint Thomas, MO 65076
Syngenta Seeds, Inc., 4343 Commerce, Court Suite 500, Lisle, IL 60532