It will have to be potted up in a one gallon pot and kept moist..pinching the top out after two sets of leaves have formed is advisable as you are wanting to let this baby focus on growing it's roots and not vine its little heart out...I would keep it in a pot until I saw roots coming out of the bottom of the pot..I like sinking the pot into the soil where you can remember where it is to make sure it doesn't dry out...Jeanne

Ditto to what Jeanne said although I have only sunk my pots in the ground in the fall to let them grow out over the winter since the ground serves as insulation allowing the roots to continue growing further into the winter. I have threatened to do so in the spring but have always just let them sit in a place where they get morning sun and afternoon shade. I am not sure if heat would be an issue in zone 5 depending on where you are.

I would be hesitant buying clematis from anyone selling them as bulbs because use of that term shows they don't know much about clematis.