I live in Maine, and we can still get frost some nights in early to mid May. I really don't want to wait to plant them until late May, so I planted my rhizomes in planter pots inside in mid-April. I used a basic vegetable garden mix of soil I found at the hardware store, put each rhizome in its own plant pot, and after about a week I started having sprouts. I have them setting in front of a picture window that gets sun for about 8 hours a day, and after a few weeks they are doing very well. Hopefully it warms up soon and I can put them into the ground because one of them has a shoot that is about 8 inches tall. I plant like this every year with vegetables for the garden, so I don't think its going to be much different with hops plants either. Its a good way to get things started without worrying about the plants dieing off from frost.