Foam and fleece 



-Covered 

 -Unprotected 



45 

 40 

 35 

 30 

 25 

 20 

 15 

 10 

 5 

 



^ CM 



5 S 



t- CM 



Date 



^ 5 



Heated greenhouse 



-Covered 

 -Unprotected 



a. 



E 



Date 



ket, and a heated greenhouse resulted in 

 similar plant survival. 



• A heated greenhouse for overwintering 

 these species may be most effective if 

 run with a thermostat setting below 

 freezing to protect against severe drops 

 in temperature and with good ventila- 

 tion in the spring to avoid soft re- 

 growth that would be susceptible to dis- 

 ease. 



• Single foam is clearly the cheapest 

 (and easiest to install) of the coverings 

 tested, but it is important to note that 

 growers should plan for protection un- 

 der more severe conditions than those 

 in which we tested. Although we did 

 not see major differences between un- 

 heated coverings, we assume that adding 

 more layers of protection would increase 

 plant survival in lower temperatures. 

 The cost of crop losses are likely to far 

 outweigh costs of adding another layer 

 of covering or building a greenhouse 



structure — and these potential crop 

 losses should be considered by growers 

 when deciding on an overwintering sys- 

 tem. 



• The project generated worthwhile in- 

 formation, but running temperature tri- 

 als over more severe winter conditions 

 is important to develop a tougher evalu- 

 ation of these overwintering materials. 



• Media and container size were not as 

 important as plant temperature in deter- 

 mining winter survival. 



Linda Bilodeau worked on this project 

 for her B.S. honors dissertation with 

 Dr. Paul Fisher at the Department 

 of Plant BioloQi, University of New 

 Hampshire. Peter van Berkum is co- 

 owner of Van Berkum Nursery. Funding 

 was provided by the UNH Agricultural 

 Experiment Station and plant material 

 was donated by Van Berkum Nursery. 



Literature Cited 



Beattie, D.J. (Ed.) 1986. "Prin- 

 ciples, practices, and comparative 

 costs of overwintering container- 

 grown landscape plants." South 

 Cooperative Series Bulletin 313. 

 May 1986. The Pennsylvania 

 State University Agricultural Sta- 

 uon, University Park, Pennsylvania. 



Bilderback, T.E. 1982. "Container 

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 Raleigh, NC: North Carolina 

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Herrick, T.A. and L. P. Perry. 

 1995. "Controlled Freezing of 

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lies, J.K., N.H. Agnew, H.G. 

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 Journal of Environmental Horticul- 

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lies, J. K. and N.H. Agnew. 

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 Patterns of Sedum spectabile x 

 telephium L. 'Autumn Joy' and 

 Sedum spectabile Boreau. 'Brilliant'." 

 HortSaence. Vol. 30:1221-1224. 



Marshall, T. J. and J. W. Holmes. 

 1988. Soil Physics, Second Edition. 

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 Cambridge, MA. pp. 202-213. 



Perry, L.P. 1997. "Keeping Their 

 Feet Warm." American Nursery- 

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Swanson, B. T. 1989. "Critical 

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 169(11): 59-63. 



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