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Shana G. Brown and James E. Klett

Stock plant productivity is an important concern for growers of ‘Snow Angel’ coral bells (Heuchera sanguinea) because this variety produces a limited number of basal cuttings. The objective of the study was to determine the best growth substrate and container size combination to maximize productivity of stock plants. A secondary objective was to determine if the stock plant treatments influenced the rooting of vegetative cuttings. The study used three different container sizes (2.8, 11.4, and 14.6 L) and four commercial soilless substrates that were primarily composed of the following: bark, peat, and perlite (substrate 1); bark, peat, and vermiculite (substrate 2); bark, peat, and coarse perlite (substrate 3); and peat (substrate 4). Two stock plant experiments were conducted using the same 12 treatment combinations, and a subset of those stock plants was randomly selected for the rooting studies that immediately followed each stock plant experiment. Stock plants responded to substrate treatments differently depending on the batch of substrate in which they were grown. The most successful stock plants, which produced more cuttings per plant and per square foot, as well as larger cuttings, were those grown in substrate 3 (Expt. 1) and substrate 2 (Expt. 2). Regardless of the substrate, the highest number of cuttings per square foot was obtained from stock plants grown in 2.8-L containers, indicating that the smaller containers allow for the most efficient use of space when growing ‘Snow Angel’ stock plants for 6 to 8 months. The rooting of vegetative cuttings was successful (98% to 100% of cuttings rooted after 4 weeks under mist) for all treatment combinations, although higher numbers of visible roots were produced during the second study and may be due to larger fresh weights of cuttings.

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Jennifer M. Bousselot, James E. Klett, and Ronda D. Koski

Success of extensive green roof vegetation depends primarily on associated plant species' ability to survive the low moisture content of the substrate. As a result of the well-drained nature of the substrate, plants adaptable to dry, porous soils are primarily used in extensive green roof applications. Although Sedum species have dominated the plant palette for extensive green roofs, there is growing interest in expanding the plant list for extensive green roof systems. To effectively select suitable plants, species need to be evaluated in terms of their response to gradual and prolonged dry down of the substrate. A study to determine the relative rates of dry down for 15 species was conducted in greenhouse trials. During dry downs that extended over 5 months, the substrate of succulent and herbaceous species dried down at different rates. The change in moisture content of the substrate was not consistent among succulent and herbaceous plant species during the initial 18 d of dry down. Despite differences in rate of dry down, the succulent species, as a group, maintained viable foliage for over five times longer than the herbaceous species. The revival rates of the succulent species were nearly double those of the herbaceous species. Therefore, not only are succulent species more likely to survive during periods of drought, but these species are more likely to resume growth soon after water is again made available.

Open access

Sean J. Markovic, Shana G. Brown, and James E. Klett

Stock plant productivity is an important concern for growers of mojave sage (Salvia pachyphylla) because this species produces more woody growth as the plant ages. The objective of the study was to determine the best growth substrate and container size combination to maximize stock plant productivity. A secondary objective was to determine whether the stock plant treatments influenced the rooting of vegetative cuttings. Three different container sizes (3, 12, and 15.5 qt) and four soilless substrates composed primarily of bark, peat, and perlite (substrate 1); bark, peat, and vermiculite (substrate 2); bark, peat, and coarse perlite (substrate 3); and peat (substrate 4) were used. The stock plant experiment was conducted using 12 treatment combinations, and a subset of those stock plants was selected randomly for the rooting study that immediately followed the stock plant experiment. Stock plants responded to substrate treatments differently. The most successful stock plants, which produced more cuttings per plant and per square foot, as well as larger cuttings, were those grown in substrate 3. Regardless of substrate, the highest number of cuttings per square foot was obtained from stock plants grown in 3-qt containers, indicating that the smaller containers allow for the most efficient use of space when growing mojave sage stock plants for 4 to 6 months. The rooting of vegetative cuttings was successful (88% to 100% of cuttings rooted after 4 weeks under mist) for all treatment combinations.

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Mary H. Meyer, Pamela J. Bennett, Barbara Fair, James E. Klett, Kimberly Moore, H. Brent Pemberton, Leonard Perry, Jane Rozum, Alan Shay, and Matthew D. Taylor

Landscape plant evaluations were conducted in eight states: Colorado, Minnesota, North Carolina, Ohio, Oregon, Pennsylvania, Texas, and Vermont for 17 switchgrass (Panicum virgatum) and five little bluestem (Schizachyrium scoparium) cultivars. Additional locations in Florida (Fort Lauderdale, Fort Pierce, Quincy, and Wimauma), Nebraska (Lincoln), and Lubbock and San Marcos completed 1 or 2 years of the trials. Plants were established in 2012 and data were collected for 3 years, 2013–15. Sites were asked to compile annual data on plant height, width, flowering time, fall color, pests, foliage color determined by the Royal Horticultural Society’s color chart, plant form, flowering date, floral impact, self-seeding, winter injury, landscape impact, and mortality. Texas A&M Agricultural Research and Extension Center (Overton), Florida (all four locations), and Vermont had the highest mortality rate. Southern Florida locations lost 50% of their plants by the end of 2014. Wide variation was reported for landscape impact, individual cultivar height, and width from different regions of the United States. Three of the 17 switchgrass cultivars, Cloud 9, Northwind, and Thundercloud, had a rating of 4.0 or higher averaged over six or more locations for plant form, floral, and landscape impact. ‘Shenandoah’ and ‘Warrior’ switchgrass had a rating of 4.0 or higher averaged over six or more locations for plant form and landscape impact, but not floral impact. Only one of the five little bluestem cultivars, Blue Heaven® rated 4.0 or higher, for plant form and landscape impact when averaged over six or more locations. This range of variability in landscape plant performance demonstrates the importance of local plant evaluations.