1 thing.....you might be underestimating the growth of the root system. I like those planters in the fact that it lets you utilize more of the water that you are using for that purpose. It is great for tomatoes, cucumbers, peppers, and other garden vegetables. Hops are anything but garden vegetables. Their root system is not shallow like you might think. The tap root will grow deep, like 16 to 18 feet down. It does have other roots that spread out for absorption of water closer to the surface. These are where the rhizomes come from. It may make you think that these are the main roots, because after the plant establishes itself, they are numerous and get to be fairly significant. Whether you have hops in the ground, or in a planter, the tap root is going to grow. You could probably do alright in those planters for the 1st year, maybe even the second. Eventually though, you will suffer. Either by having issues of being root bound, or worse, having the roots soaking in the bottom....rotting. The hops plant doesn't know that you have it contained, nor does it care. It is just going to do it's own thing. Try to grow, survive, and propagate it's existence. Just my 2 cents worth...