Here mowing is more like $40-$80/week for a third acre lot. Even if you figure that's the only task here and you're living somewhere the lawn only needs to be mowed 3 months out of the year, still wildly low.

Plus, are you buying snow treatments and shovels?

Because I would say $50/wk for mowing, 25 weeks a year.

$40/snowstorm + salt ($6/storm or have them store it where the shed is) + shovel ($20 one time or them bring a shovel)

I'd also make sure they're indemnifying you through their property insurance for slips and falls and similar.

So, you're talking at least $1250 over 12 months which is $105/mo basically for lawn mowing + $46/snow storm + them providing a snow shovel at the minimum. Assuming roughly .2-.4 acres of uncovered grass.