I made grow bags from landscape fabric a few years ago.

Here are the links to the Youtube videos:

Part 1:  46 seconds- This video shows you how to get the landscape fabric, available at most garden centers, ready to sew.   http://www.youtube.com/watch?v=0wQbfb0i0Yo

Part 2:  Sewing the bag using a serger:  http://www.youtube.com/watch?v=DqyOE7ZK1yg

The following article takes this portable gardening idea to a whole new level
http://www.remodelista.com/posts/a-movable-feast-berlins-community-garden

 

and also this one:  http://www.gardenista.com/posts/moveable-feast-a-pop-up-farm-in-brooklyn