Observation:
Yes! I did the Craziest thing ever and yes I planted Monstera on the ground during May in Canada.
I planted a well rooted cutting on the ground around end of May in Ontario ( zone 5 )
I planted it in clay soil with poor drainage and the plant seems to like it and grow well. Actually the one outside is growing really fast compared to the one indoors. I saw a new leaf in 2 weeks !
Enjoy the pictures below
Word of Wise:
Plant it in a well shaded area.
Water it regularly.
Check for Pests