I took my first stab at growing hops this year, with 4 cascades and 2 nugget plants. One of each cascade and nugget grew like crazy and reached 14+ feet pretty really in the season. The cascade has lots of nice looking hop cones on it, but the nugget has only sparse hop cones. the other four grew VERY slow and are quite spindly. Those four are all only about 6 feet tall at this point. My question is, do first year hops have to grow a certain amount in the first season, to guarantee that they come back next spring? Will these 6 foot plants be established enough to grow back next season, or should I plan on replacing those 4 with new rhizomes next year? Also, is this common with first year hops, or is there most likely some underlining problem here?