The problem is you are growing gingers indoors. Put them outside. Very likely the problem you have is due to low humidity inside the house. If it is too dry the edges will dry out and more or less fuse together keeping the leaves from unfurling.

Check out this link for a page on growing edible gingers. www.gingerwoodnursery.com
click on the articles tab and then click on the edible ginger faq.

-Kyle

Are you feeding it? I prefer to use osmocote with supplemental foliar feedings of miracle grow. They also definately need a dry dormant period during winter.
kevin