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dougald_gw

Global Warming and Our Hostas

dougald_gw
10 years ago

I live rurally in the Ottawa Valley but far enough away from Ottawa that the well known "heat island" effect of the city is absent. For example, last night, the official low at the airport was -27.4C (winchill close to -40C) which is about -18F. I keep my own weather records and consistly run from 3 to 5C colder at night than the airport. Last night was no exception coming in around -31C. This is, incidently, far from the record low for the date of -34C set in 1981 or from the all time record low of -40C.

The USDA puts Ottawa in Zone 5 but most of the rest of the Valley in 4 though of course the USDA class does not take into account the frost free growing days, rainfall, sunshine heat units or other important climatic details. It seems to me that for this locale, most of the gains from "global warming" are related to the higher night time lows than an overall even gain in temps.

Here we are frost free on average from about May 20 through Sept 12 and this is highly variable. The result is that hostas start to send up their first pips in mid May unfurling by early June. They last for just 100 days befopre being wiped out by an early frost.

Hostas are said to be hardy to USDA Zone 3 so certainly the Zone 4 conditions experienced here should have no effect. Are there folks on the forum growing hostas in Zone 3 or even Zone 2 (Saskatoon SK or Cochrane ON) to verify the cold hardiness? Is the length of growing season a more important constraint?

My hostas seem to be well adapted to the conditions but what I would like to get at is ... do they grow more slowly, do they take longer to reach maturity, do they present colour and texture better or worse. In other words, what represents the optimum climate for hosta rearing?

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