Hops are very cold and snow tolerant and can be put in the ground as soon as the soil is "workable".  They can also be started in pots for transplanting later on. 

Hops should be planted in early spring (from late March to early May in Western New York).  They're a perennial vine that die back down to the ground completely in the fall.  In early spring the dark green, sometimes purplish vines come back with increasing vigor each year.  Hops require a trellis and will grow to 20 feet or more (though not usually in the first year planted).  It's best not to expect a significant harvest in the first or even second year but in year three should start producing well. They do best in full sun and prefer well drained soil.  Hops vines with their unusual green flowers or "cones" add beauty and interest to ornamental gardens, but be forewarned, they do spread!