Thank you for your kind words.
No, I didn't use any heater till February, when we got that cold front from russia, which bought here 15 exceptionally cold days (cold because the temperature never raised over 0C (32F) for over a week, and here it is pretty exceptional - while the absolute minimum wasn't so low, -6C (21F) at max). Every heating is due the heat stored in the water drums, heated from the sun. So that temperature I posted are without the heater. I didn't post the temperature with the heater on in february, because i think they weren't meaningfull in the context of a solar passive structure, and after the middle of february we didn't experience any serious cold front till spring.
The data presented are obtained that way: every week i opened the structure, went in, and read the maximum-minimun thermometer, registered the minimum, resetted, then close the structure. Later, at home, i watched for meteo sites, controlled the closest meteo station (which happens to be just 2 km away from my home) for the minimum of temperature of the week, and registered it too. I suppose (but this may indeed be false) that the minimun temperature in the greenhouse happened the same day of the minimun temperature outside; anyway over the week the minimun inside and the minimu outside seems to keep 10C (18F) degree of difference.
Yes, 6C is really cold but i can assure that the plant managed to surive (even if with minor leaf damage) even to lower temperatures. During the cold front of february the thermometer showed a minimun of 3C, and that temperature may have lasted for 2 weeks (I didn't open the strucutre during those weeks to avoid lowering the internal temperature even more, but this what I read when i opened it). I can't tell for sure, but this may have happened.
What I can tell you for sure is that 2 years ago, after a some snow, 3 mangos (1 kensingotn pride and 2 seedling) managed to survive without any damage to a snow-covered unheated greenhouse, where the temperature remained at 1°C for 48 hours. The plant were left there on purpose, to test their cold tolerance. They were in pots.
Regarding fruting, I found two interesting thing on the pakistany book someone posted here some time ago. 4.4°C destroys fruits and flowers. Having less than 15,5°C will kill pollen tubes. The max pollen viability happens when night temperatures are over 17°C. Moreover, that book states: "It is observed that low night temperatures of 10-15C days and day temperatures below 27C can induce flowering, but fruit will be small and seedless and may fall before ripening. In some varieties flowers are damaged at low temperature of even at 10C, if such temperatures occur at full bloom."
Actually I never got under 13°C since the start of the flowering but I guess that it was still in the "risky zone", and I must have had those temperatures too soon. Since un unmounted my structure during flowring (April-May), I guess that next years I'll keep that mounted till june.
Yes, I'll buy some more mangos, I must find the one wich works for here!
But since apparently grafting seems so easy I guess that next years I'll buy maybe scions, because importing plants is a pain!
I'll updage the tread with some pictues at the end of summer, when I'll know ho much the plant has been able to grow this summer.
Topic: My new grow room + update on the mango tree in Canada! Lycheeluva chime in! (Read 12932 times)