Last year, in a moment of rash enthusiasm, I sowed seeds of mecha-meck, (Ipomoea pandurata) a "hardy" sweetpotato relative, along with those of Ipomoea leptophylla, the manroot. Mecha-meck has a fairly wide distribution along the eastern side of the USA, where winters are usually far more severe than the ones we get here. Manroot is found in the Great Plains region and the high deserts of New Mexico and Colorado, where once again, the winters are much colder than we experience.
Last winter's cold snap has proved a challenge for plants which I would usually consider to be fairly hardy. Mecha-meck has turned out to be a casualty too.
Somewhat cautiously, I tipped the mecha-meck roots out of their pots. Several had disappeared altogether. This is one of the disarticulated cadavers I discovered.
The root resembled sweetpotato in texture, with none of the appeal: the rank smell emanating from its decaying flesh dissuaded me from putting any in my mouth. Wimp.
I am now left with (perhaps) one survivor. I've potted it up and brought it indoors in the hope that it will live to see another summer.
The manroots (menroots?) to the left of the single mech-meck, have apparently fared much better, apart from the odd slug hole. This seems surprising considering their supposed predilection for desert habitats. Not exactly man-sized, they are a bit puny.
All this goes to show that hardiness is a fluid concept and is dependent on more than simple thermometer readings. I suspect that our combination of excess soil moisture, suddenly followed by sub-zero temperatures, simply confused the cellular processes which protect plant tissues from freezing. None of which is much consolation when I think about it.
So whatever else it is, mecha-meck is not as hardy in our slushy, wet and occasionally cold winters as I had hoped. Manroot seems somewhat hardier. As mecha-meck is an obligate outcrosser, the one remaining plant, if it survives, will flower its heart out and still remain barren. Poor thing. But maybe I can snatch some sort of victory from this defeat. It turns out that I. leptophylla and I. pandurata are very closely related, so it might be possible to combine the best qualities (whatever they are) of both species by crossing them. Any seeds developing on the mecha-meck plant would be interspecies hybrids and that could lead somewhere interesting. Or not, of course.
The fact that the high altitude I. leptophylla has overwintered more successfully than mecha-meck suggests that I should continue the hunt for the seeds of Ipomoea minuta, which grows at even higher altitudes. Then there are also those New Guinea sweetpotato seeds, from the chilly highland region. I really ought to try some of them too. Now where did I put them?
Last winter's cold snap has proved a challenge for plants which I would usually consider to be fairly hardy. Mecha-meck has turned out to be a casualty too.
Somewhat cautiously, I tipped the mecha-meck roots out of their pots. Several had disappeared altogether. This is one of the disarticulated cadavers I discovered.
The root resembled sweetpotato in texture, with none of the appeal: the rank smell emanating from its decaying flesh dissuaded me from putting any in my mouth. Wimp. 
All this goes to show that hardiness is a fluid concept and is dependent on more than simple thermometer readings. I suspect that our combination of excess soil moisture, suddenly followed by sub-zero temperatures, simply confused the cellular processes which protect plant tissues from freezing. None of which is much consolation when I think about it.
So whatever else it is, mecha-meck is not as hardy in our slushy, wet and occasionally cold winters as I had hoped. Manroot seems somewhat hardier. As mecha-meck is an obligate outcrosser, the one remaining plant, if it survives, will flower its heart out and still remain barren. Poor thing. But maybe I can snatch some sort of victory from this defeat. It turns out that I. leptophylla and I. pandurata are very closely related, so it might be possible to combine the best qualities (whatever they are) of both species by crossing them. Any seeds developing on the mecha-meck plant would be interspecies hybrids and that could lead somewhere interesting. Or not, of course.
The fact that the high altitude I. leptophylla has overwintered more successfully than mecha-meck suggests that I should continue the hunt for the seeds of Ipomoea minuta, which grows at even higher altitudes. Then there are also those New Guinea sweetpotato seeds, from the chilly highland region. I really ought to try some of them too. Now where did I put them?
Comments
Best of luck with the sweet potatoes, cold hardy varieties would save those permaculture types some work I think *wink*
Just on the news tonight, in case we (or our plants) hadn't noticed "...this winter there was 60% of the average sunshine."
Frost survival can be related to the depth of the underground plant parts. Those in pots are more vulnerable than those planted in the ground, and those that naturally grow deep are insulated from all but very long periods of frost.
But yes, plants evolved for cold/dry winters have a hard time in UK winter conditions.
As for winter survival. I think you might be right in that it is possible that they could not handle being in a damp spot then freezing but also we often get extensive insulating snowcover meaning survival beyond what the air temperature would suggest. However, the prairies are not always so privledged what with the winds blowing off this insulating blanet which is thinner due to decreased rain in winter there.
Are you planning on trying to select for tasty roots of the hardy sweets or do a wide cross or either?