Freezing and Chilling Tolerance in Common Plants

Friday March 21, 2014 – 7:30 p.m. at the Almonte United Church Social Hall

Speaker: Hugh Hope 

Topic: Freezing and Chilling Tolerance in Common Plants


Who among us hasn’t looked at the blackened remains of squash plants following a late spring frost? But yet surprisingly cilantro seedlings nearby are undamaged. Why do native maple flowers tolerate low temperatures that kill every flower on a magnolia bush the same cold night? Hugh will talk about the many conundrums surrounding plants that die in the fall, plants that live all winter with no problem and some introduced southern species that survive immersion in liquid nitrogen. A talk about this real cool topic is just not complete without considering why several successive nights at temperatures around +10C will chill damage your precious tomatoes that you recently transplanted into the garden. Differences between chilling and freezing damage will be outlined. We will also dig a bit deeper (pun intended) into the topic of what parts of plants tolerate freezing, how much freezing and why this toleration is minimal in mid summer but very high by early December.

Speaker’s Profile:

Hugh Hope has spent a lifetime involved one way or another with plants. He grew up on a dairy farm at Leitrim just south of Ottawa and learned at an early age about the very direct connection between a hoe and the family vegetable garden. For his B.Sc studies at Carleton University he studied plant structure, function and classification and also chemistry. Combining his background in plants and chemistry he went on to do a Masters degree at Carleton in plant physiology and a Ph.D in plant biochemistry at Dalhousie University in Halifax. Following two years of postdoctoral research work on the chemical changes in plants caused by air pollution at the University of California, Riverside Campus, he began work at Agriculture Canada first in Quebec City and later at the Central Experimental Farm. His research work concentrated on studies of the effects of low temperatures on biochemical reactions in plants using important agricultural plants such as alfalfa and grain corn. In retirement, Hugh has been an avid gardener and has collections of rhododendrons, tree peonies and hellebores as well as alpine plants.

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