[Program information (data, reports, photographs) can be found on the internet at: http://www.uark.edu/campus-resources/cotinus/arboretum_html/planteval.html]

January 2006

This completes the seventh year of the statewide plant evaluation program. The current team of cooperators includes Dr. Jim Robbins, Dr. Jon Lindstrom, and Manjula Carter.

The three test sites are the Hope Research Center (USDA cold hardiness zone 8), the Little Rock/Cooperative Extension Service property (zone 7a), and the Fayetteville Horticulture Research farm (zone 6b). As much as possible the three test sites were prepared in a similar manner. Full sun plants were grown in row-type beds 3’ wide with a 7’ grass alley. Plant groups are planted together (i.e. trees are planted together). Trees are spaced 10’ apart, shrubs 6’ apart, and herbaceous perennials 4’ apart. The Little Rock site was planted on April 18, 2002; Fayetteville was planted on April 5, 2002; Hope planted on April 5, 2002. Irrigation at all three sites is by a drip system. Plants were fertilized and mulched after planting. Post-emergent herbicides were used at all three test sites. No disease or insect control was implemented during the first year. To maintain a tree-like habit, trees are pruned following final growth measurements. Pruning consists of removing the bottom 1/3 of limbs. SHRUBS are NOT pruned. Final growth measurements were taken at Little Rock on October 10; Fayetteville on October 13; and Hope on October 19.

Weather data at all three test sites is attached (see attached graph).

Bailey Nursery donated 8’ BR plants. Performance has been fair at Little Rock and Hope and good in Fayetteville. Tree height decreases as we go from zone 6 to zone 8 (Fayetteville: 152"; Little Rock 137", Hope 76"). Statewide average tree height is 122" with a trunk caliper @ 6" of 2.0". Two of the three trees died at Hope.

Briggs Nursery donated 1-gal plants. Performance has been good so far. Only one tree has died statewide at that was at Little Rock. Based on the color variation in underside leaf surface pubescence, we wonder if we have more than one clone. Two trees in Fayetteville flowered for the first time in June and July 2005. Plants really took off in growth in this second year increasing in height statewide by 32". Statewide average tree height is 115" with a trunk caliper @ 6" of 3.3".

Briggs Nursery donated 1-gal plants. Performance has been good at Hope, fair at Little Rock, but abysmal in Fayetteville. At Fayetteville in 2003, two plants died and the third killed to the ground with limited regrowth the following spring. Plants flowered at Hope and Little Rock in 2005. Foliage is distorted by an unidentified leaf spot in Little Rock. Statewide average tree height is 102" with a trunk caliper @ 6" of 1.8".

Griffith Propagation Nursery donated 2" liner plants. Both clones of Clethra tested performed very poorly at all three sites. By the end of 2004 all 9 plants are dead at all three test sties. If it had simply been this cultivar, we would have concluded high mortality was related to small plant size. However, the sister clone ‘White Dove’, also performed poorly during an Arkansas summer.

Flowerwood Nursery donated 3-gal container plants. Similar to sister seedling, ‘Sixteen Candles’, ‘White Dove’ struggled during an Arkansas summer. Flowering is about 1 week later than ‘Sixteen Candles’. Statewide all plants are dead.

Cuttings were rooted from University of Georgia plants and planted as a 1-gal. Growth rate was outstanding at all three test sites. This might be a good substitute for those looking for Juniperus virginiana. Average plant size statewide is 105" tall by 103" wide. Plants are wider than they are tall at Fayetteville (85" tall x 101" wide).

Flowerwood Nursery donated 3-gal container plants. Six of the nine plants planted, including all the plants in Fayetteville, died during the first summer. Only two plants remain at Hope (zone 8). Average plant size on remaining plants is 34" tall x 43" wide. Plants display a lovely soft pink flower in mid-April at Hope.

1-gal plants were purchased from Colvos Creek Nursery. We are very impressed with the performance of this broadleaf evergreen in Little Rock and Hope during the first two years even though it was planted in full sun at all three sites. Most of the growth continues to be vertical. This plant would benefit from pruning at an early age which we do not do in our program. Plants in Fayetteville were seriously affected by cold weather in October and November of 2002 and all three died. The bark on all three plants has split at the base of the plant. All three plants growing in Little Rock died in 2004. The deaths at LR would appear to be related to root rot in our heavy soil and a very wet spring. All plants are dead statewide by the end of 2005.

1-gal plants were purchased from Nurseries Caroliniana. Performance was good at all three sites. Two of the nine plants are dead statewide. Plants flowered in the first year. Average final plant size was 32" tall by 73" wide (broader than tall). Plants flowered the last 2 weeks in March in Fayetteville, Little Rock and Hope. Up close the flower is exquisite. This might make a nice spreading broadleaf evergreen in place of junipers or hollies.

Flowerwood Nursery donated 3-gal container plants. Plant growth was good at all 3 sites. Average final plant size was 82" tall by 61" wide. Plants are significantly shorter at Fayetteville (61") compared to Little Rock (91") and Hope (93"). Foliage is a dark blue-green. New growth on this holly was slow to harden-off in Fayetteville and was damaged by the first frost of the season.

1-gal plants were purchased from Nurseries Caroliniana. Performance was good at Hope and Little Rock. All plants are dead at Fayetteville (zone 6). Average plant size was 77" tall by 77" wide. Foliage is a very clean, medium green. Plants have a unique cream-white flower that is mostly hidden by the evergreen foliage. Flowers appear in early April and then sporadically through October.

1-gal plants were purchased from Forestfarm Nursery. Growth was good at Little Rock and Hope. All plants are dead in Fayetteville. Plants flowered in Little Rock in early May and fruits were noted in mid-September. Average final plant size was 41" tall by 40" wide.

Briggs Nursery donated 4" liner plants. Truly a remarkable success story in Little Rock and Hope for the first two years. Only one plant remains statewide and that is located at Little Rock. Plants, while not thriving, did well considering they were grown in full Arkansas sun. Plants in Little Rock flowered in late April, 2004 and lasted for about 2 weeks.

1-gal plants were purchased from Nurseries Caroliniana. Here is an interesting situation since we now understand that Thuja × ‘Green Giant’ (2001 plant) and this culitvar are likely identical. Plants grew exceptionally well at all three sites. One plant died at Little Rock in 2004 due to what looks like a root rot. Average final plant size was 116" tall by 57" wide.

1-quart plants were purchased from Colvos Creek Nursery. Plants started fine but were killed by the hot Arkansas summer. A shadier location is suggested for future plantings.

Hines Nurseries donated 5-gal container plants. The plants came labeled as ‘Gloire de Versailles’ but they are actually the cultivar ‘Henri Desfossé. ‘Gloire de Versailles’ has larger, broader leaves and bigger flower panicles. This plant is probably the star for the year. These plants begin to flower in May and as of late October were still in flower. Unbelievable flower display and the fruits mature with a beautiful cherry red that lasts until a hard frost. Average final plant size was 74" tall by 105" wide. One plant has died (Little Rock).

The Ornamentals team would like to express their sincere appreciation to the cooperating nurseries (Flowerwood Nurseries, Briggs Nursery, Dr. Michael Dirr- University of Georgia, Griffith Propagation Nursery, and Hines Nurseries) for donating the plants for this season’s trial and to the Arkansas Green Industry Association for financial support.