Q.Why are my monkey puzzle trees dying?
I planted some monkey puzzle tree seeds last winter and successfully grew them indoors for about 6 months. In March, I repotted them (2-3 per pot)and put them in my outdoor greenhouse. Since then, one by one, they are slowly dying and I wondered whether anyone could give me some advice, please? When can monkey puzzle seedlings be planted outdoors? Is it too humid in a greenhouse for them? Many thanks! Sarah

Monkey Puzzle is hardy to zones 7 thru 11.
What temperature was the greenhouse kept at during the winter months?
Here is an excellent article that explain the care and growing conditions.
https://www.gardeningknowhow.com/houseplants/monkey-puzzle/monkey-puzzle-indoors.htm