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 one third 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 May 2, 2006. The predominant plant spacing in the trials was 18 inches × 24 inches (in-row x between-row spacing). Seven plants of each entry were used to evaluate landscape performance and ratings were taken weekly.
We are especially grateful to the North Carolina Commercial Flower Growers Association for their generous financial support of our student intern, Corley Hughes.
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 other departmental staff and the volunteers of the JC Raulston Arboretum who assisted in transplanting and maintaining the annual beds throughout the growing season....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 May 23, 2006 (about three weeks after planting) through October 10, 2006. 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 summer 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 8 weeks of evaluation. This group may prefer cooler 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 very warm temperatures or flower as daylengths start to shorten, 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. In many cases our results have confirmed some excellent reputations, for others, it's a first time notice. Coreopsis 'Early Sunrise' performed up to its expected historical par as a first class performer; the impatiens cultivars Fiesta Sparkler Hot Pink, Pixie Hot Rose, and Tempo Pearl met our test, indicating excellent plant to plant uniformity; 'Blushing Susie' thunbergia was outstanding in this regard, most noteworthy in that it is a vine; and it was good to see the 'Aztec Cherry Red' verbena up there, too, as this group of plants is finding quite a popular following.
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. Making this cut were Dianthus 'Amazon Rose Magic', Diascia 'Whisper Salmon Red Improved', Geranium 'Florever Red', Petunia 'Ramblin Lavender' and 'Sweet Surprise Purple', Phlox 'Intensia Neon Pink', Portulaca 'Margarita Scarlet', and two vincas, 'Heatwave Red' and 'SunStorm Mix'. Please note that we thought a lot of the phlox for many other reasons, so high variability is not the sole measure for rejection. A litany of marigolds also fell onto our list but Raleigh is normally a tough go for these plants, so we shouldn't be too surprised.......the 'Atlantis' series, 'Hero' series, 'Discovery Orange', and the 'Safari' series we tested were very variable. To be fair, there are many reasons for a lack of uniformity, most likely of which would simply be the result of our normal or extreme weather. This year, it would be safe to assume that our exceptional rainfall had a significant impact on plant performance.......but variance can also help us identify the very best for our area.
Please get in touch with these companies if you have specific questions regarding individual species and cultivars.
All-America Selections, 1311 Butterfield Road, Suite 310, Downers Grove, IL60515-5606
Ball Seed Co., P. O. Box 335, West Chicago, IL 60185
J.P. Bartlett Co., Inc., 578 Boston Post Road, Sudbury, MA 01776
Ernst Benary of America, Inc., 1444 Larson Street, Sycamore, IL 60178-9705
Ball FloraPlant, 622 Town Road, West Chicago, IL 63185
BodgerSeeds Ltd., 1800 North Tyler Avenue, South El Monte, CA 91733-3618
Campbell Road Nursery, 2804 Campbell Road, Raleigh, NC 27606
Dummen USA, 2542 Williams Road, Batavia, IL60510
Fides North America, P.O. Box 1860, 4050 Alajuela, Costa Rica
Fischer USA, Inc., 6899 Winchester Circle, Boulder, CO 80301-3507
Goldsmith Seeds, Inc., 2280 Hecker Pass Hwy, Gilroy, CA 95021-1349
Grimes Seeds and Plants, 11335 Concord-Hambden, Concord, OH 44077
Jackson and Perkins Wholesale, P O Box 9100,Medford, OR 97501
PanAmerican Seed Co., P. O. Box 438, West Chicago, IL 60185
Proven Winners, 1021 River Ridge Lane, Saint Thomas, MO 65076
Sakata Seed America, Inc., P.O. Box 174, Dry Ridge, KY 41035-0174
Syngenta Seeds, Inc., 4343 Commerce Court Ste. 500, Lisle, IL 60532