planting hops in pots

I have my hops planted in pots but i'm not getting any growth on 3 of them (1 is officially dead) and the one that is growing is about 8 inches tall. this is after 5 weeks in the soil. I was wondering what type of potting soil people are using in their pots (assuming theirs' are growing)? I ordered a replacement for the one that died and 2 others of the 2 that are not growing. this week i'll end up repotting them and want to use a method that works for other people. i used miracle grow for flowers and vegies.
When i repot, i was thinking about putting a bit of sand to cover the bottom of the pot to make sure it drains good. any suggestions would be great!

How big are your pots? I would never plant hops in pots unless they were about 6+ feet in diameter. Even then, they won't do as well as they would in the ground. Their root system is very expansive...

I live in MI and have yet to pot a rhizome. Just put those babies in the ground!! My cascade was laid four years ago into a mix of my soil and my soil. It's doing great, and flowered a bit the first season! The three that I got this year had a mix of potting soil and humus/manure in the raised barrel ring beds. I really don't think it matters unless you live on clay or in the desert.

The thing about potted plants is that you need to use potting soil that drains well, and is specifically designed for container gardens. I know you are probably thinking, why should I go out and buy dirt, I mean my yard is full of it, well buying dirt is key to getting the thing to grow. Additionally being in a pot makes the soil dry out faster, so you need to water more frequently, rather than adding a little at a time make sure you soak that thing very well and let it get soaked all the way through. Any potting soil will work fine, it isn't that big a deal.

If it wasn't for the likelyhood that i would be moving in the new few months into a house i'm trying to buy, i would just toss em in the dirt. but since i am (hopefully) buying a house, i'ld just have to dig them up from the dirt and i figured its easier to put them into the ground from the pot.
the pots i'm using are 18" across and 18" or so tall.

I planted mine in pots and am not having any problems...yet. I'll be closing on a new house next week, so next weekend the hop garden gets built.
I have a magnum and cascade that are growing slowly, mainly due to the number of shoots coming up (5 or 6 per rhizome). Both of these have shoots that are about a foot tall. I also have a nugget that only sprouted two shoots, one of which is already approaching 5 feet high. I just got some regualr potting soil at Lowe's and then followed drections as if I was planting them in the ground (using mulch and all that). I just got some El Cheapo pots (they're roughly the same size as the ones mentioned by OP) so that when I permanently plant them, I can just cut the pots away and put the whole thing into the ground.

I've got second year Chinook and Fuggle each in half wine barrels. That's 30 gallons each. They are both nearly 8 feet tall right now. I have some first year Cascades in 9 gallon pots that are about 3 feet tall now. I used a combo of topsoil, peat moss, and composted manure.