I have my lucky bamboo growing in soil because I found that easier. I too transitioned mine from water to soil as well.

The mix I used is Miracle Grow Moisture Control potting soil, a little sand and mixed in orchid bark. My plants have grown large and stay very healthy for years now.

I do not know how necessary the orchid bark is in the mix. However, the recipe was recommended at the time and I found it works very well.