Tending to Mums

I getting contradictory advice on tending to my newly planted mums. I've been told by one good friend, who lives in Queens, NY, that late every fall, he cuts his mums down to the soil line and every year they come back bigger and bushier. And I've been told by a local North Jersey friend who has hothouses, and grows commercial flowers for a living that I should only prune to shape them in the late fall and that cutting them to the soil line will only kill them. The area where I planted them will have snow piled on them by my town's snow plows, so I'd prefer the cut to soil line method, if feasible. Still, I'd like to know whose advice I should follow.
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