To season the roots and wither the leaves, allow the roots to lie in the field for 4-5 days, protected from direct sun and frost with straw. Do not wash before storage. Small amounts can simply be refrigerated in a perforated plastic bag. Any plastic bags may be used. Monitor the roots occasionally, sprinkling with water if they are drying, or increasing ventilation if there is any slime or mold.
Imagination is the chief requirement here.
We created our trial forcing areas with materials on hand. The more carefully controlled conditions, the more letter-perfect the chicons. The root tops can extend above the containers but should be of relatively even height. Too-long roots can be trimmed a little. If your containers are slightly shallow, the roots can be placed in them at a slight angle.