Progress 10/01/08 to 10/01/11
Outputs
OUTPUTS: Many retail and wholesale nurseries grow herbaceous perennials, and many such growers in northern climates need to successfully overwinter plants either in production, or held from the previous year, in overwintering structures such as greenhouses. This study contributed to the knowledge of how cycling temperatures (hot and cold) in winter affect hardiness, as well as soil moisture and plant age (vigor) effects. Results will be shared with industry both in their publications and presentations, in journal articles, and on the author's Perry's Perennial Pages website. Based on these results, future studies will investigate the effect on hardiness of midwinter deacclimation temperatures. PARTICIPANTS: Sarah Kingsley-Richards is a MS graduate student in the Department of Plant and Soil Science. Dr. Leonard Perry, Extension Professor, was the PI. Supplemental funding was provided by partner organizations New England Grows, a New England conference annually funding research and education in ornamental horticulture; and the Vermont Nursery and Landscape Association. TARGET AUDIENCES: ornamental greenhouse and nursery growers PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Perennial growers overwintering plant stock require information to assist in deciding which containerized plants are most likely to successfully overwinter. Such results will result in significant economic savings in both fuel and plant losses. Three studies on container-grown herbaceous perennials were conducted to examine the influence of plant age, soil moisture, and temperature cycling date on cold hardiness. In January, plants were exposed to controlled freezing temperatures of -2, -5, -8, -11, and -14C and then returned to a 3-5C greenhouse. In June, plants were assessed using a visual rating scale of 1-5 (1 = dead, 3-5 = increasing salable quality, varying by cultivar) and dry weights of new growth were determined. Controlled freezing in November and March were also included in the third study. In the first study, two ages of plants were exposed to controlled freezing temperatures in January. For Geranium x cantabrigiense 'Karmina', age had no effect on either rating or dry weight in one study year. In two Sedum 'Matrona' study years, age had no effect on dry weight but ratings were higher for older plants than younger plants in the first year and higher for younger plants than older plants in the second year. In two Leucanthemum x superbum 'Becky' study years, age had an effect on both rating and dry weight which were both generally higher for younger plants than older plants. In the second study, plants were maintained in pots at two different soil moisture levels prior to exposure to controlled freezing temperatures in January. Coreopsis 'Tequila Sunrise' and Carex morrowii 'Ice Dance' showed no effect on either rating or dry weight from soil moisture level. Soil moisture level had no effect on dry weight but ratings were higher for Geranium x cantabrigiense 'Cambridge' wet plants and for Heuchera 'Plum Pudding' dry plants. Carex laxiculmus 'Hobb' (Bunny Blue TM) soil moisture level had an effect where dry weight was higher for dry plants. Means at were of salable quality for Geranium and Heuchera at all temperatures and Carex laxiculmus at temperatures above -11C. The effects of soil moisture level on Carex oshimensis were inconclusive. In the third Study, during November, January, and March, plants were subjected to temperature cycling treatments prior to exposure to controlled freezing temperatures. Geranium x cantabrigiense 'Cambridge' were more tolerant of both temperature cycling and freezing temperatures in January and an increased number ofcycles in November had an advantageous effect. Sedum 'Matrona' were more tolerant of temperature cycling and freezing temperatures in January and an increased number of cycles in March had an advantageous effect. Leucanthemum x superbum 'Becky' were more tolerant of temperature cycling in January in the second year ofthe study and an increased number of cycles in November had an advantageous effect in the first year and in all months in the second year.
Publications
- Kingsley-Richards, Sarah L. (2011) Influence of plant age, soil moisture, and temperature cycling date on container-grown herbaceous perennials. MS thesis. Department of Plant and Soil Science, University of Vermont. May.
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Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: Many growers of herbaceous perennials in northern climates need to successfully overwinter plants either in production, or held from the previous year. Often this is done in greenhouses which can heat during sunny winter days. This study this past winter continued to address this effect of mid-winter possible deacclimation by warm, or cycling, temperatures. Based on outcomes, a similar study with the same Shasta daisy and a foamflower will be repeated, to get a better understanding of these effects and on a wider range of species. Results will be shared with industry both in their publications and presentations, and on the author's Perry's Perennial Pages website. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: nursery and greenhouse growers through extension outreach in presentations and online PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The second winter of this study examined a marginally hardy species of perennial shasta daisy (Becky) and a normally hardy selection of yarrow (Apricot Delight), both popular perennials. Result showed that in midwinter (January), even just 5 days at 16C was enough to deacclimate plants, resulting in loss in subsequent subzero soil temperatures. Returning plants to 4C during the night did not compensate for the deacclimation. There were no differences between one or two weeks held at 16C prior to subsequent freezing. Plants in a normally fluctuating greenhouse (-2 to 8C, mean 4C), continuous 4 or 2C showed no differences, all surviving similarly. This study also supported previous results that plants not sufficiently rooted had poor winter survival, so this study will be repeated one more year. Growers overwintering perennials will benefit from knowing the effect of mid-winter high temperatures and cycling on subsequent plant survival when exposed to freezing. This will enable them to save money either in plant losses, scheduling labor and covering treatments more appropriately, and saving costs and fuel in heating if not needed.
Publications
- No publications reported this period
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Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: This project has as its components several industry funded applied projects relating to hardiness of herbaceous perennials. These include field and controlled freezing trials, both to determine lowest minimal winter temperatures, and effects of variables such as soil type and fertility, and mid-winter deacclimation on subsequent winter survival. Specific genera such as coralbells, and groupings such as groundcovers, also will be tested. Results will be shared in presentations, articles, and on the author's Perry's Perennial Pages website. PARTICIPANTS: Dr Leonard Perry, PI, University of Vermont. Funding provided by New England Grows, Vermont Nursery and Landscape Assn., New England Floriculture, Perennial Plant Association, New Hampshire Floriculture Endowment. TARGET AUDIENCES: greenhouse and nursery perennial growers, home gardeners PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
During the winter of 2008-2009 three studies were conducted. Nine cultivars of groundcover plants were frozen under controlled conditions during midwinter to one of 5 subzero temperatures (-2,-5,-8,-11,-14C) then evaluated in spring for survival and regrowth parameters. Of these 5 were found hardy to the lowest temperature with no differences among treatments, the other 4 were moderately hardy. In the second study, 5 species of popular herbaceous perennials, grown the previous season in 6 media and fertilizer combinations were overwintered outdoors using standard overwintering fabrics as used by growers. There were no differences in survival among treatments. The third study examined midwinter deacclimation of a marginally hardy species of perennial Salvia (Rhapsody in Blue) and a normally hardy selection of Sedum (Neon), both popular perennials. Results showed that in midwinter (January), even just 5 days at 16C was enough to deacclimate plants, resulting in loss in subsequent subzero soil temperatures. The greatest loss was at lower soil temperatures on freezing, -8C and below for Sedum and -11C and below for Salvia. Returning plants to 4C during the night did not compensate for the deacclimation. There were no differences between one or two weeks held at 16C prior to subsequent freezing. Plants in a normally fluctuating greenhouse (-2 to 8C, mean 4C), continuous 4 or 2C showed no differences, all surviving similarly. Both growers and home gardeners will benefit from these studies by knowing to what temperatures, and under what conditions in winter, herbaceous perennials will withstand. Perennials are one of the most important groups of plants sold, and bought by gardeners, in the ornamental horticulture industry. Such information will lead to more success at plant selection and overwintering in northern regions. Such controlled freezing studies on perennial hardiness are not being done in other parts of northern latitudes.
Publications
- No publications reported this period
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