Living la vida loca can be fun but a fruit tree capable to live in zone 4 instead of its regular zone 5 would be magical!
I would like to know if the following reasoning has any sense or would be fallacious:
A fruit trees (for the sake of conversation, a paw paw tree Campbell NC-1 supposed to be hardy to zone 5) has been grown in a pot spending spring, summer and autumn in a greenhouse and winter in a heated shed at 5 Celcius degrees for all its life up to now.
This tree is now 4 year old but looks like a 6 six old paw paw and is in very good general health. Had 6 flowers last spring for the first time.
Would you say that this particular tree is more capable to endure a zone 4 winter (with good blanket to pass the winter season) and has a reasonable chance to survive in a zone 4 environment for the rest of it’s life with or without blankets?
Where are you? When you say celsius i think of canada and how they raise the zone rating so if your 4b canada you are 3b usa. From my understanding you would need to protect it from snap colds and long cold spells and probably keep it well watered during that process? Personally i think you should keep doing what has been working so far.