What is the best way to store a canoe. I mean should it be placed flat with the hull up or should it be on the side like a kayak?
For some canoes, it won’t matter, but generally upside down, on the gunwales, and supported by sawhorses or hanging racks or some such about a third of the way from the ends.
Extreme heat can cause trouble with plastics, and putting wood on the ground can cause rot. I have seen a canoe broken from being stored under an eave and a roof avalanche coming down and hitting it all at once.
And kept out of direct sun.
Unless, of course, you’re trying to kill the mildew formed by keeping it in the shade.
Same as a kayak
i.e. upside down, high enough to clear possible snow on the gorund and covered from sun. People only put kayaks on the side for space economy reasons.